Version October 2024
Nirmatrelvir/ritonavir includes ritonavir, a strong CYP3A inhibitor, which may lead to greater exposure of certain concomitant medications, resulting in potentially severe, life-threatening, or fatal events.
Prior to prescribing nirmatrelvir/ritonavir: 1) Review all medications taken by the patient to assess potential drug-drug interactions with a strong CYP3A inhibitor like nirmatrelvir/ritonavir and 2) Determine if concomitant medications require a dose adjustment, interruption, and/or additional monitoring.
Consider the benefit of nirmatrelvir/ritonavir treatment in reducing hospitalization and death, and whether the risk of potential drug-drug interactions for an individual patient can be appropriately managed.
COVID-19, mild to moderate; treatment: Note: For patients at high risk of progression to severe COVID-19, including hospitalization or death (Ref).
Oral: Nirmatrelvir 300 mg with ritonavir 100 mg, administered together, twice daily for 5 days; initiate as soon as possible after COVID-19 diagnosis, and within 5 days of symptom onset. After initiating treatment with nirmatrelvir/ritonavir, if hospitalization is required, completion of 5-day course is at the health care provider's discretion (Ref).
Missed dose: If a dose is missed within 8 hours of usual administration time, the missed dose should be administered as soon as possible, and normal dosing schedule should resume. If a dose is missed by more than 8 hours, the missed dose should not be administered, and dosing should resume at the next scheduled administration time. Do not double the dose to make up for a missed dose.
Dosage adjustment for concomitant therapy: Significant drug interactions exist, requiring dose/frequency adjustment or avoidance. Consult drug interactions database for more information.
Altered kidney function:
eGFR ≥60 to <90 mL/minute: No dosage adjustment necessary.
eGFR ≥30 to <60 mL/minute: Nirmatrelvir 150 mg and ritonavir 100 mg, administered together, twice daily for 5 days.
eGFR <30 mL/minute: Use is not recommended according to the manufacturer; however, the risk of toxicity is likely to be minimal with a 5-day course of treatment.
Nirmatrelvir 300 mg and ritonavir 100 mg once on day 1, then 150 mg nirmatrelvir and 100 mg ritonavir once daily for 4 more days to complete a 5-day course (Ref). Note: This regimen requires manipulation of the blister card packaging to achieve the recommended dose.
Alternative dosing: Based on retrospective data in a limited number of patients: Nirmatrelvir 150 mg and ritonavir 100 mg twice daily for 5 days was reasonably well tolerated (Ref).
Hemodialysis, intermittent (thrice weekly): Use is not recommended according to the manufacturer; however, the risk of toxicity is likely to be minimal with a 5-day course of treatment. Note: These regimens require manipulation of the blister card packaging to achieve the recommended dose.
Patients ≥40 kg: Nirmatrelvir 300 mg and ritonavir 100 mg once on day 1, then 150 mg nirmatrelvir and 100 mg ritonavir once daily for 4 more days to complete a 5-day course; when scheduled dose falls on a dialysis day, administer after dialysis (Ref).
Patients <40 kg: Nirmatrelvir 150 mg and ritonavir 100 mg once on day 1, then nirmatrelvir 150 mg and ritonavir 100 mg every 48 hours for 2 more doses to complete a 5-day course; when scheduled dose falls on a dialysis day, administer after dialysis (Ref).
Peritoneal dialysis: Use is not recommended according to the manufacturer; however, the risk of toxicity is likely to be minimal with a 5-day course of treatment. Note: These regimens require manipulation of the blister card packaging to achieve the recommended dose.
Patients ≥40 kg: Nirmatrelvir 300 mg and ritonavir 100 mg once on day 1, then 150 mg nirmatrelvir and 100 mg ritonavir once daily for 4 more days to complete a 5-day course (Ref).
Patients <40 kg: Nirmatrelvir 150 mg and ritonavir 100 mg once on day 1, then nirmatrelvir 150 mg and ritonavir 100 mg every 48 hours for 2 more doses to complete a 5-day course (Ref).
Mild or moderate impairment (Child-Pugh class A or B): No dosage adjustment necessary.
Severe impairment (Child-Pugh class C): Use is not recommended (has not been studied).
Refer to adult dosing.
(For additional information see "Nirmatrelvir and ritonavir: Pediatric drug information")
Note: Nirmatrelvir and ritonavir is supplied as 2 separate products packaged together in a blister card for each day of dosing; prescriptions should specify the numeric dose (mg) of each active ingredient (Ref).
COVID-19, mild to moderate; treatment: Children ≥12 years and Adolescents, weighing ≥40 kg: Oral: Nirmatrelvir 300 mg and ritonavir 100 mg, administered together, twice daily for 5 days; initiate as soon as possible following COVID-19 diagnosis and within 5 days of symptom onset. Patients who require hospitalization due to severe or critical COVID-19 after initiating treatment outpatient should complete the full 5-day treatment course per healthcare providers' discretion (Ref). Note: The combination of nirmatrelvir and ritonavir has not been studied in pediatric patients; emergency use authorization from the FDA is based on likelihood of similar exposures in patients ≥12 years of age weighing ≥40 kg.
Dosage adjustment for concomitant therapy: Significant drug interactions exist, requiring dose/frequency adjustment or avoidance. Consult drug interactions database for more information.
Children ≥12 years and Adolescents, weighing ≥40 kg: Oral:
eGFR ≥60 mL/minute: No dosage adjustment necessary (Ref).
eGFR 30 to <60 mL/minute: Nirmatrelvir 150 mg and ritonavir 100 mg, administered together twice daily for 5 days (Ref).
eGFR <30 mL/minute: Use is not recommended; appropriate dose not determined (Ref).
Children ≥12 years and Adolescents, weighing ≥40 kg:
Mild or moderate impairment: No dosage adjustment necessary (Ref).
Severe impairment: Not recommended for use (has not been studied) (Ref).
The following adverse drug reactions and incidences are derived from product labeling unless otherwise specified. Reported adverse reactions are for adults. Also see Ritonavir monograph.
1% to 10%: Gastrointestinal: Diarrhea (3%), dysgeusia (5%)
Postmarketing:
Cardiovascular: Bradycardia (Ref), hypertension, syncope (Ref)
Dermatologic: Pruritus (Ref), severe dermatological reaction (including Stevens-Johnson syndrome and toxic epidermal necrolysis), skin rash (Ref)
Gastrointestinal: Abdominal pain, nausea, pancreatitis (Ref), vomiting
Hypersensitivity: Anaphylaxis, hypersensitivity reaction
Nervous system: Headache, malaise
Respiratory: Dyspnea (Ref)
Significant hypersensitivity (eg, toxic epidermal necrolysis, Stevens-Johnson syndrome) to nirmatrelvir, ritonavir, or any component of the formulation; coadministration with drugs that are highly dependent on CYP3A for clearance and for which elevated concentrations are associated with serious and/or life-threatening reactions (eg, alfuzosin, amiodarone, colchicine, dihydroergotamine, dronedarone, eletriptan, eplerenone, ergotamine, finerenone, flecainide, flibanserin, ivabradine, lomitapide, lovastatin, lurasidone, methylergonovine, midazolam [oral], naloxegol, pimozide, propafenone, quinidine, ranolazine, sildenafil [when used for the treatment of pulmonary arterial hypertension], silodosin, simvastatin, tolvaptan, triazolam, ubrogepant, voclosporin); coadministration with strong CYP3A inducers. Note: For some strong CYP3A inducers (eg, apalutamide, carbamazepine, lumacaftor/ivacaftor, phenobarbital, phenytoin, primidone, rifapentine, rifampin, St. John's wort), initiation of nirmatrelvir/ritonavir should be delayed after discontinuation of the CYP3A inducer due to the delayed offset of the CYP3A inducer.
Significant drug interactions exist, requiring dose/frequency adjustment or avoidance. Consult drug interactions database for more information.
Canadian labeling: Additional contraindications (not in US labeling): Coadministration with ergonovine, fusidic acid, neratinib, rivaroxaban, salmeterol, vardenafil, venetoclax, voriconazole.
Concerns related to adverse effects:
• Hepatic effects: Hepatic transaminase elevations, clinical hepatitis, and jaundice have occurred in patients receiving ritonavir; use with caution in patients with preexisting liver disease, liver enzyme abnormalities, or hepatitis.
• Hypersensitivity reactions: Hypersensitivity reactions, including anaphylaxis, serious skin reactions (including toxic epidermal necrosis and Stevens-Johnson syndrome), and other hypersensitivity reactions, have been reported. Discontinue therapy and initiate appropriate treatment if signs and symptoms of anaphylaxis or severe hypersensitivity occurs.
Disease-related concerns:
• Renal impairment: Systemic exposure of nirmatrelvir is increased in patients with renal impairment. Dosage adjustment recommended in patients with eGFR ≥30 to <60 mL/minute; the manufacturer recommends against use in patients with eGFR <30 mL/minute.
Other warnings/precautions:
• Risk of HIV-1 protease inhibitor drug resistance: Ritonavir is also an HIV-1 protease inhibitor. There may be a risk of HIV-1 developing resistance in patients with uncontrolled or undiagnosed HIV-1 infection.
• Viral rebound: Viral rebound and recurrence of COVID-19 symptoms have been reported in some patients after completing treatment. The frequency, mechanism, and clinical implications of these events are unclear. Viral rebound and recurrence of COVID-19 symptoms can occur in the absence of treatment. Concern for viral rebound and/or recurrence of symptoms should not be a reason to avoid antiviral therapy (NIH 2023).
Paxlovid approved by the FDA May 2023.
Therapy packs intended for use in patients with eGFR ≥60 mL/minute contain a total of 20 tablets of nirmatrelvir 150 mg and 10 tablets of ritonavir 100 mg. The tablets are packaged as 5 daily-dose blister cards each containing 4 nirmatrelvir 150 mg tablets and 2 ritonivir 100 mg tablets.
Therapy packs intended for use in patients with eGFR 30 to <60 mL/minute contain a total of 10 tablets of nirmatrelvir 150 mg and 10 tablets of ritonavir 100 mg. The tablets are packaged as 5 daily-dose blister cards each containing 2 nirmatrelvir 150 mg tablets and 2 ritonivir 100 mg tablets.
Excipient information presented when available (limited, particularly for generics); consult specific product labeling. [DSC] = Discontinued product
Tablet Therapy Pack, Oral:
Paxlovid (150/100): Nirmatrelvir 10 x 150 mg and ritonavir 10 x 100 mg (2 ea, 4 ea [DSC], 20 ea)
Paxlovid (300/100): Nirmatrelvir 20 x 150 mg and ritonavir 10 x 100 mg (3 ea, 6 ea [DSC], 30 ea)
No
Tablet Therapy Pack (Paxlovid (150/100) Oral)
10 x 150 MG &10 x 100MG (per each): $83.40
Tablet Therapy Pack (Paxlovid (300/100) Oral)
20 x 150 MG &10 x 100MG (per each): $55.60
Disclaimer: A representative AWP (Average Wholesale Price) price or price range is provided as reference price only. A range is provided when more than one manufacturer's AWP price is available and uses the low and high price reported by the manufacturers to determine the range. The pricing data should be used for benchmarking purposes only, and as such should not be used alone to set or adjudicate any prices for reimbursement or purchasing functions or considered to be an exact price for a single product and/or manufacturer. Medi-Span expressly disclaims all warranties of any kind or nature, whether express or implied, and assumes no liability with respect to accuracy of price or price range data published in its solutions. In no event shall Medi-Span be liable for special, indirect, incidental, or consequential damages arising from use of price or price range data. Pricing data is updated monthly.
Excipient information presented when available (limited, particularly for generics); consult specific product labeling.
Tablet Therapy Pack, Oral:
Paxlovid (150/100): Nirmatrelvir 10 x 150 mg and ritonavir 10 x 100 mg (20 ea)
Paxlovid (300/100): Nirmatrelvir 20 x 150 mg and ritonavir 10 x 100 mg (30 ea)
Oral: Administer with or without food. Swallow tablets whole; do not chew, break, or crush. Nirmatrelvir must be coadministered with ritonavir; failure to correctly coadminister may result in insufficient nirmatrelvir plasma levels.
NG tube : The manufacturer of Paxlovid, Pfizer, had previously posted information on how to prepare and administer nirmatrelvir and ritonavir tablets via NG tube on the medical information section of their website. However, they have subsequently removed this information and now state they are unable to make any recommendations regarding alternate preparations for administration.
Enteral: Nirmatrelvir must be coadministered with ritonavir; failure to correctly coadminister may result in insufficient nirmatrelvir plasma concentrations (Ref).
Oral: Administer with or without food. Swallow tablets whole; do not chew, break, or crush (Ref).
Nasogastric: The manufacturer of Paxlovid, Pfizer, had previously posted information on how to prepare and administer nirmatrelvir and ritonavir tablets via NG tube on the medical information section of their website. However, they have subsequently removed this information and now state they are unable to make any recommendations regarding alternative preparations for administration.
Missed dose: If <8 hours since dose was due, the missed dose should be administered as soon as possible, and normal dosing schedule should resume. If ≥8 hours since dose was due, the dose should be skipped, and dosing should resume at the next scheduled administration time. Do not double the dose to make up for a missed dose (Ref).
COVID-19, treatment, mild to moderate: Treatment of mild to moderate COVID-19 in adults who are at high risk for progression to severe COVID-19, including hospitalization or death.
Limitations of use: Not approved for use as pre- or postexposure prophylaxis for prevention of COVID-19. In addition, not recommended for use in patients requiring hospitalization for COVID-19 (Ref).
Note: Medical conditions and factors associated with increased risk for progression to severe COVID-19 have been identified by the CDC and can be found at https://www.cdc.gov/coronavirus/2019-ncov/hcp/clinical-care/underlyingconditions.html. This list is not exhaustive and is updated as the science evolves. Consider the benefit:risk for an individual patient.
Two different packaging configurations for nirmatrelvir and ritonavir are available: Paxlovid 300 mg;100 mg Dose Pack to be used for patients with normal renal function or mild renal impairment (eGFR ≥60 mL/minute) and Paxlovid 150 mg;100 mg Dose Pack to be used in patients with moderate renal impairment (eGFR ≥30 to <60 mL/minute). Nirmatrelvir and ritonavir is not recommended in patients with severe renal impairment (CrCl <30 mL/minute). When prescribing nirmatrelvir and ritonavir, the numeric dose for each active ingredient should always be specified (eg, Paxlovid 300 mg;100 mg, Paxlovid 150 mg;100 mg).
Substrate of CYP1A2 (minor), CYP2B6 (minor), CYP2D6 (minor), CYP3A4 (major), P-glycoprotein/ABCB1 (minor); Note: Assignment of Major/Minor substrate status based on clinically relevant drug interaction potential; Inhibits CYP2D6 (weak), CYP3A4 (strong), MRP2, P-glycoprotein/ABCB1; Induces CYP1A2 (weak), CYP2B6 (moderate), CYP2C19 (weak), CYP2C9 (weak), UGT1A1
Note: Interacting drugs may not be individually listed below if they are part of a group interaction (eg, individual drugs within “CYP3A4 Inducers [Strong]” are NOT listed). For a complete list of drug interactions by individual drug name and detailed management recommendations, use the drug interactions program by clicking on the “Launch drug interactions program” link above.
Abemaciclib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Abemaciclib. Management: In patients taking abemaciclib at a dose of 200 mg or 150 mg twice daily, reduce the dose to 100 mg twice daily when combined with strong CYP3A4 inhibitors. In patients taking abemaciclib 100 mg twice daily, decrease the dose to 50 mg twice daily. Risk D: Consider therapy modification
Acalabrutinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Acalabrutinib. Risk X: Avoid combination
Adagrasib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Adagrasib. Management: Avoid use of adagrasib and strong CYP3A4 inhibitors until adagrasib concentrations have reached steady state (ie, after approximately 8 days of therapy). Risk D: Consider therapy modification
Ado-Trastuzumab Emtansine: CYP3A4 Inhibitors (Strong) may increase serum concentrations of the active metabolite(s) of Ado-Trastuzumab Emtansine. Specifically, strong CYP3A4 inhibitors may increase concentrations of the cytotoxic DM1 component. Management: Avoid concomitant use of ado-trastuzumab emtansine and strong CYP3A4 inhibitors when possible. Consider alternatives that do not inhibit CYP3A4 or consider administering after CYP3A4 inhibitor discontinuation. Monitor for toxicities if combined. Risk D: Consider therapy modification
Afatinib: P-glycoprotein/ABCB1 Inhibitors may increase the serum concentration of Afatinib. Management: If combined, administer the P-gp inhibitor simultaneously with, or after, the dose of afatinib. Monitor closely for signs and symptoms of afatinib toxicity and if the combination is not tolerated, reduce the afatinib dose by 10 mg. Risk D: Consider therapy modification
Albendazole: Nirmatrelvir and Ritonavir may decrease the serum concentration of Albendazole. Risk C: Monitor therapy
ALfentanil: CYP3A4 Inhibitors (Strong) may increase the serum concentration of ALfentanil. Management: If use of alfentanil and strong CYP3A4 inhibitors is necessary, consider dosage reduction of alfentanil until stable drug effects are achieved. Frequently monitor patients for respiratory depression and sedation when these agents are combined. Risk D: Consider therapy modification
Alfuzosin: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Alfuzosin. Risk X: Avoid combination
Aliskiren: Nirmatrelvir and Ritonavir may increase the serum concentration of Aliskiren. Risk X: Avoid combination
Alitretinoin (Systemic): CYP3A4 Inhibitors (Strong) may increase the serum concentration of Alitretinoin (Systemic). Management: Consider reducing the alitretinoin dose to 10 mg when used together with strong CYP3A4 inhibitors. Monitor for increased alitretinoin effects/toxicities if combined with a strong CYP3A4 inhibitor. Risk D: Consider therapy modification
Almotriptan: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Almotriptan. Management: Limit initial almotriptan dose to 6.25 mg and maximum dose to 12.5 mg in any 24-period when used with a strong CYP3A4 inhibitor. Avoid concurrent use in patients with impaired hepatic or renal function. Risk D: Consider therapy modification
Alosetron: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Alosetron. Risk C: Monitor therapy
ALPRAZolam: Nirmatrelvir and Ritonavir may increase the serum concentration of ALPRAZolam. Management: Reduce the alprazolam dose by 50% when a patient is started on nirmatrelvir/ritonavir and alprazolam together, or when nirmatrelvir/ritonavir is initiated in a patient already treated with alprazolam. Risk D: Consider therapy modification
Amiodarone: Nirmatrelvir and Ritonavir may increase the serum concentration of Amiodarone. Risk X: Avoid combination
AmLODIPine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of AmLODIPine. Risk C: Monitor therapy
Antihepaciviral Combination Products: Nirmatrelvir and Ritonavir may increase the serum concentration of Antihepaciviral Combination Products. Antihepaciviral Combination Products may increase the serum concentration of Nirmatrelvir and Ritonavir. Risk C: Monitor therapy
Apixaban: Inhibitors of CYP3A4 (Strong) and P-glycoprotein may increase the serum concentration of Apixaban. Management: US labeling recommends a 50% apixaban dose reduction in patients who would otherwise receive 5 or 10 mg twice daily, and avoiding in patients who would otherwise receive 2.5 mg twice daily. Canadian labeling lists any combined use as contraindicated. Risk D: Consider therapy modification
Aprepitant: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Aprepitant. Risk X: Avoid combination
ARIPiprazole: CYP3A4 Inhibitors (Strong) may increase the serum concentration of ARIPiprazole. Management: Aripiprazole dose reductions are required for indications other than major depressive disorder. Dose reductions vary based on formulation, initial starting dose, CYP2D6 genotype, and use of CYP2D6 inhibitors. See full interaction monograph for details. Risk D: Consider therapy modification
ARIPiprazole Lauroxil: CYP3A4 Inhibitors (Strong) may increase serum concentrations of the active metabolite(s) of ARIPiprazole Lauroxil. Management: Decrease aripiprazole lauroxil dose to next lower strength if used with strong CYP3A4 inhibitors for over 14 days. No dose adjustment needed if using the lowest dose (441 mg). Max dose is 441 mg in CYP2D6 PMs or if also taking strong CYP2D6 inhibitors. Risk D: Consider therapy modification
Artemether and Lumefantrine: Protease Inhibitors may increase the serum concentration of Artemether and Lumefantrine. Specifically, the concentrations of lumefantrine may be increased. Protease Inhibitors may decrease the serum concentration of Artemether and Lumefantrine. Specifically, concentrations of artemether and dihydroartemisinin (DHA), the active metabolite of artemether, may be decreased. Risk C: Monitor therapy
Artesunate: Nirmatrelvir and Ritonavir may decrease serum concentrations of the active metabolite(s) of Artesunate. Nirmatrelvir and Ritonavir may increase the serum concentration of Artesunate. Risk C: Monitor therapy
Asciminib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Asciminib. Risk C: Monitor therapy
Astemizole: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Astemizole. Risk X: Avoid combination
Atidarsagene Autotemcel: Antiretroviral Agents may diminish the therapeutic effect of Atidarsagene Autotemcel. Risk X: Avoid combination
Atogepant: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Atogepant. Management: For treatment of episodic migraine, the recommended atogepant dose is 10 mg once daily with a concurrent strong CYP3A4 inhibitor. If used for treatment of chronic migraine, concurrent use of atogepant with strong CYP3A4 inhibitors should be avoided. Risk D: Consider therapy modification
Atorvastatin: Nirmatrelvir and Ritonavir may increase the serum concentration of Atorvastatin. Management: Consider temporarily discontinuing atorvastatin during treatment with nirmatrelvir/ritonavir. It is not necessary to hold atorvastatin either prior to or after completion of nirmatrelvir/ritonavir treatment. Risk D: Consider therapy modification
Atovaquone: Nirmatrelvir and Ritonavir may decrease the serum concentration of Atovaquone. Risk C: Monitor therapy
Avacopan: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Avacopan. Management: Decrease the avacopan dose to 30 mg once daily during coadministration with strong CYP3A4 inhibitors. Risk D: Consider therapy modification
Avanafil: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Avanafil. Risk X: Avoid combination
Avapritinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Avapritinib. Risk X: Avoid combination
Axitinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Axitinib. Management: Avoid concurrent use of axitinib with any strong CYP3A inhibitor whenever possible. If a strong CYP3A inhibitor must be used with axitinib, a 50% axitinib dose reduction is recommended. Risk D: Consider therapy modification
Barnidipine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Barnidipine. Risk X: Avoid combination
Beclomethasone (Systemic): CYP3A4 Inhibitors (Strong) may increase the serum concentration of Beclomethasone (Systemic). Risk C: Monitor therapy
Bedaquiline: CYP3A4 Inhibitors (Strong) may increase serum concentrations of the active metabolite(s) of Bedaquiline. CYP3A4 Inhibitors (Strong) may increase the serum concentration of Bedaquiline. Management: Limit duration of concurrent use of bedaquiline with strong CYP3A4 inhibitors to no more than 14 days, unless the benefit of continued use outweighs the possible risks. Monitor for toxic effects of bedaquiline, including QTc interval prolongation. Risk D: Consider therapy modification
Benidipine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Benidipine. Risk C: Monitor therapy
Benperidol: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Benperidol. Risk C: Monitor therapy
Benzhydrocodone: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Benzhydrocodone. Specifically, the concentration of hydrocodone may be increased. Risk C: Monitor therapy
Berotralstat: P-glycoprotein/ABCB1 Inhibitors may increase the serum concentration of Berotralstat. Management: Decrease the berotralstat dose to 110 mg daily when combined with P-glycoprotein (P-gp) inhibitors. Risk D: Consider therapy modification
Betamethasone (Systemic): Nirmatrelvir and Ritonavir may increase the serum concentration of Betamethasone (Systemic). Risk C: Monitor therapy
Bictegravir: UGT1A1 Inducers may decrease the serum concentration of Bictegravir. Risk C: Monitor therapy
Bilastine: P-glycoprotein/ABCB1 Inhibitors may increase the serum concentration of Bilastine. Risk X: Avoid combination
Blonanserin: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Blonanserin. Risk X: Avoid combination
Bortezomib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Bortezomib. Risk C: Monitor therapy
Bosentan: Nirmatrelvir and Ritonavir may increase the serum concentration of Bosentan. Management: Consider alternative COVID-19 treatments in patients taking bosentan. If nirmatrelvir and ritonavir must be used, discontinue bosentan at least 36 hours before initiation of nirmatrelvir and ritonavir. Monitor for increased bosentan toxicities. Risk D: Consider therapy modification
Bosutinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Bosutinib. Risk X: Avoid combination
Brentuximab Vedotin: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Brentuximab Vedotin. Specifically, concentrations of the active monomethyl auristatin E (MMAE) component may be increased. Risk C: Monitor therapy
Brexpiprazole: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Brexpiprazole. Management: Reduce brexpiprazole dose 50% with strong CYP3A4 inhibitors; reduce to 25% of usual if used with both a strong CYP3A4 inhibitor and a CYP2D6 inhibitor in patients not being treated for MDD, or strong CYP3A4 inhibitor used in a CYP2D6 poor metabolizer. Risk D: Consider therapy modification
Brigatinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Brigatinib. Management: Avoid concurrent use of brigatinib with strong CYP3A4 inhibitors when possible. If combination cannot be avoided, reduce the brigatinib dose by approximately 50%, rounding to the nearest tablet strength (ie, from 180 mg to 90 mg, or from 90 mg to 60 mg). Risk D: Consider therapy modification
Bromocriptine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Bromocriptine. Management: Consider alternatives to the use of bromocriptine with strong CYP3A4 inhibitors. If combined, monitor closely for increased bromocriptine toxicities and consider bromocriptine dose reductions. Risk D: Consider therapy modification
Bromperidol: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Bromperidol. Risk C: Monitor therapy
Brotizolam: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Brotizolam. Risk C: Monitor therapy
Budesonide (Oral Inhalation): Nirmatrelvir and Ritonavir may increase the serum concentration of Budesonide (Oral Inhalation). Risk C: Monitor therapy
Budesonide (Systemic): CYP3A4 Inhibitors (Strong) may increase the serum concentration of Budesonide (Systemic). Management: Avoid the concomitant use of CYP3A4 inhibitors and oral budesonide. If patients receive both budesonide and a strong CYP3A4 inhibitor, they should be closely monitored for signs and symptoms of corticosteroid excess. Risk D: Consider therapy modification
Budesonide (Topical): Nirmatrelvir and Ritonavir may increase the serum concentration of Budesonide (Topical). Management: Consider the risks of systemic corticosteroid adverse effects versus the benefits of coadministration. Monitor patients for systemic corticosteroid adverse effects if combined. Risk D: Consider therapy modification
Buprenorphine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Buprenorphine. Risk C: Monitor therapy
BuPROPion: Nirmatrelvir and Ritonavir may decrease the serum concentration of BuPROPion. Risk C: Monitor therapy
BusPIRone: CYP3A4 Inhibitors (Strong) may increase the serum concentration of BusPIRone. Management: Limit the buspirone dose to 2.5 mg daily and monitor patients for increased buspirone effects/toxicities if combined with strong CYP3A4 inhibitors. Dose adjustments of buspirone or a strong CYP3A4 inhibitor should be based on clinical assessment. Risk D: Consider therapy modification
Butorphanol: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Butorphanol. Risk C: Monitor therapy
Cabazitaxel: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Cabazitaxel. Management: Concurrent use of cabazitaxel with strong inhibitors of CYP3A4 should be avoided when possible. If such a combination must be used, consider a 25% reduction in the cabazitaxel dose. Risk D: Consider therapy modification
Cabotegravir: UGT1A1 Inducers may decrease the serum concentration of Cabotegravir. Risk X: Avoid combination
Cabozantinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Cabozantinib. Management: Avoid use of a strong CYP3A4 inhibitor with cabozantinib if possible. If combined, decrease cabozantinib capsules (Cometriq) by 40 mg from previous dose or decrease cabozantinib tablets (Cabometyx) by 20 mg from previous dose. Risk D: Consider therapy modification
Calcifediol: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Calcifediol. Risk C: Monitor therapy
Calcitriol (Systemic): CYP3A4 Inhibitors (Strong) may increase the serum concentration of Calcitriol (Systemic). Risk C: Monitor therapy
Canagliflozin: Nirmatrelvir and Ritonavir may decrease the serum concentration of Canagliflozin. Risk C: Monitor therapy
Cannabidiol: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Cannabidiol. Risk C: Monitor therapy
Cannabis: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Cannabis. More specifically, tetrahydrocannabinol and cannabidiol serum concentrations may be increased. Risk C: Monitor therapy
Capivasertib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Capivasertib. Management: Avoid concomitant use of capivasertib with strong CYP3A4 inhibitors when possible. If combined, reduce the capivasertib dose to 320 mg twice daily for 4 days, followed by 3 days off. Monitor patients closely for adverse reactions. Risk D: Consider therapy modification
Capmatinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Capmatinib. Risk C: Monitor therapy
CarBAMazepine: Nirmatrelvir and Ritonavir may increase the serum concentration of CarBAMazepine. CarBAMazepine may decrease the serum concentration of Nirmatrelvir and Ritonavir. Risk X: Avoid combination
Cariprazine: CYP3A4 Inhibitors (Strong) may increase serum concentrations of the active metabolite(s) of Cariprazine. Specifically, concentrations of didesmethylcariprazine (DDCAR), the primary active metabolite of cariprazine, may increase. CYP3A4 Inhibitors (Strong) may increase the serum concentration of Cariprazine. Management: Decrease cariprazine dose 50% (4.5 mg to 1.5 mg or 3 mg; 1.5 mg to 1.5 mg every other day) if starting a strong CYP3A4 inhibitor. If on a strong CYP3A4 inhibitor, start cariprazine at 1.5 mg day 1, 0 mg day 2, then 1.5 mg daily. May increase to 3 mg daily Risk D: Consider therapy modification
Celiprolol: P-glycoprotein/ABCB1 Inhibitors may increase the serum concentration of Celiprolol. Risk C: Monitor therapy
Ceritinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Ceritinib. Management: Avoid this combination whenever possible. If combined, the ceritinib dose should be reduced by approximately one-third (to the nearest 150 mg). Resume the prior ceritinib dose after cessation of the strong CYP3A4 inhibitor. Risk D: Consider therapy modification
ChlordiazePOXIDE: CYP3A4 Inhibitors (Strong) may increase the serum concentration of ChlordiazePOXIDE. Risk C: Monitor therapy
Cilnidipine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Cilnidipine. Risk C: Monitor therapy
Cilostazol: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Cilostazol. Management: Decrease the dose of cilostazol to 50 mg twice daily when combined with strong CYP3A4 inhibitors. Risk D: Consider therapy modification
Cinacalcet: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Cinacalcet. Risk C: Monitor therapy
Cisapride: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Cisapride. Risk X: Avoid combination
Cladribine: Inhibitors of Equilibrative Nucleoside (ENT1) and Concentrative Nucleoside (CNT3) Transport Proteins may increase the serum concentration of Cladribine. Management: Avoid concomitant use of ENT1 or CNT3 inhibitors during the 4 to 5 day oral cladribine treatment cycles whenever possible. If combined, consider an ENT1 or CNT3 inhibitor dose reduction and separation in the timing of administration. Risk D: Consider therapy modification
Clarithromycin: Protease Inhibitors may decrease serum concentrations of the active metabolite(s) of Clarithromycin. Protease Inhibitors may increase the serum concentration of Clarithromycin. Management: Do not exceed clarithromycin doses greater than 1,000 mg/day in patients taking protease inhibitors. If CrCL is 30 to 60 mL/min, reduced clarithromycin dose 50%. If CrCL is less than 30 mL/min, reduced clarithromycin dose 75%. Risk D: Consider therapy modification
Clindamycin (Systemic): CYP3A4 Inhibitors (Strong) may increase the serum concentration of Clindamycin (Systemic). Risk C: Monitor therapy
Clobetasone: Nirmatrelvir and Ritonavir may increase the serum concentration of Clobetasone. Risk C: Monitor therapy
ClonazePAM: CYP3A4 Inhibitors (Strong) may increase the serum concentration of ClonazePAM. Risk C: Monitor therapy
Clopidogrel: Nirmatrelvir and Ritonavir may diminish the antiplatelet effect of Clopidogrel. Nirmatrelvir and Ritonavir may decrease serum concentrations of the active metabolite(s) of Clopidogrel. Management: Avoid coadministration of clopidogrel and nirmatrelvir/ritonavir when possible. Consider using alternative COVID-19 therapy or an alternative antiplatelet such as prasugrel if clinically appropriate. Risk D: Consider therapy modification
Clorazepate: Nirmatrelvir and Ritonavir may increase the serum concentration of Clorazepate. Risk C: Monitor therapy
CloZAPine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of CloZAPine. Risk C: Monitor therapy
Cobicistat: Nirmatrelvir and Ritonavir may increase the serum concentration of Cobicistat. Risk C: Monitor therapy
Cobimetinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Cobimetinib. Risk X: Avoid combination
Codeine: CYP3A4 Inhibitors (Strong) may increase serum concentrations of the active metabolite(s) of Codeine. Risk C: Monitor therapy
Colchicine: Nirmatrelvir and Ritonavir may increase the serum concentration of Colchicine. Risk X: Avoid combination
Conivaptan: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Conivaptan. Risk X: Avoid combination
Copanlisib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Copanlisib. Management: If concomitant use of copanlisib and strong CYP3A4 inhibitors cannot be avoided, reduce the copanlisib dose to 45 mg. Monitor patients for increased copanlisib effects/toxicities. Risk D: Consider therapy modification
Corticosteroids (Nasal): Nirmatrelvir and Ritonavir may increase the serum concentration of Corticosteroids (Nasal). Risk C: Monitor therapy
Corticosteroids (Ophthalmic): Nirmatrelvir and Ritonavir may increase the serum concentration of Corticosteroids (Ophthalmic). Risk C: Monitor therapy
Corticosteroids (Topical): Nirmatrelvir and Ritonavir may increase the serum concentration of Corticosteroids (Topical). Risk C: Monitor therapy
Cortisone: Nirmatrelvir and Ritonavir may increase the serum concentration of Cortisone. Risk C: Monitor therapy
Crizotinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Crizotinib. Management: Avoid concomitant use of crizotinib and strong CYP3A4 inhibitors whenever possible. If combined use cannot be avoided, crizotinib dose reductions are required, which vary according to indication. See full interaction monograph for details. Risk D: Consider therapy modification
CycloPHOSphamide: Protease Inhibitors may enhance the adverse/toxic effect of CycloPHOSphamide. Specifically, the incidences of neutropenia, infection, and mucositis may be increased. Protease Inhibitors may increase the serum concentration of CycloPHOSphamide. Risk C: Monitor therapy
CycloPHOSphamide: CYP2B6 Inducers (Moderate) may increase serum concentrations of the active metabolite(s) of CycloPHOSphamide. Risk C: Monitor therapy
CycloSPORINE (Systemic): Nirmatrelvir and Ritonavir may increase the serum concentration of CycloSPORINE (Systemic). Management: Consider avoiding this combination if possible and using alternative anti-COVID-19 therapy if appropriate. If coadministration is required, consider reducing cyclosporine dose by 80% and monitoring cyclosporine concentrations closely. Risk D: Consider therapy modification
CYP3A4 Inducers (Moderate): May decrease the serum concentration of Nirmatrelvir and Ritonavir. Risk C: Monitor therapy
CYP3A4 Inducers (Strong): May decrease the serum concentration of Nirmatrelvir and Ritonavir. Risk X: Avoid combination
CYP3A4 Inhibitors (Strong): May increase the serum concentration of Nirmatrelvir and Ritonavir. Risk C: Monitor therapy
Cyproterone: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Cyproterone. Risk C: Monitor therapy
Dabigatran Etexilate: Nirmatrelvir and Ritonavir may increase the serum concentration of Dabigatran Etexilate. Risk C: Monitor therapy
Dabrafenib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Dabrafenib. Management: Consider alternatives to any strong CYP3A4 inhibitor for patients being treated with dabrafenib. If such a combination cannot be avoided, monitor closely for evidence of dabrafenib-related adverse effects. Risk D: Consider therapy modification
Daclatasvir: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Daclatasvir. Management: Decrease the daclatasvir dose to 30 mg once daily if combined with a strong CYP3A4 inhibitor. Risk D: Consider therapy modification
Dapoxetine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Dapoxetine. Risk X: Avoid combination
Daridorexant: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Daridorexant. Risk X: Avoid combination
Darifenacin: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Darifenacin. Management: Limit the darifenacin dose to no more than 7.5 mg daily if combined with strong CYP3A4 inhibitors. Monitor patients for increased darifenacin toxicities (eg, dry mouth, constipation, headache, CNS effects) when these agents are combined. Risk D: Consider therapy modification
Darolutamide: Inhibitors of CYP3A4 (Strong) and P-glycoprotein may increase the serum concentration of Darolutamide. Risk C: Monitor therapy
Dasatinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Dasatinib. Management: This combination should be avoided if possible. If combined, decrease dasatinib dose from 140 mg to 40 mg, 100 mg to 20 mg, or 70 mg to 20 mg. For patients taking 60 mg or 40 mg daily, stop dasatinib until the CYP3A4 inhibitor is discontinued. Risk D: Consider therapy modification
Deferasirox: Nirmatrelvir and Ritonavir may decrease the serum concentration of Deferasirox. Risk C: Monitor therapy
Deflazacort: Nirmatrelvir and Ritonavir may increase serum concentrations of the active metabolite(s) of Deflazacort. Management: Consider reducing the deflazacort dose to one-third the recommended dose during coadministration with nirmatrelvir and ritonavir. Risk D: Consider therapy modification
Delamanid: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Delamanid. Management: Increase ECG monitoring frequency if delamanid is combined with strong CYP3A4 inhibitors due to the risk for QTc interval prolongation. Continue frequent ECG assessments throughout full delamanid treatment period. Risk D: Consider therapy modification
Delavirdine: May increase the serum concentration of Nirmatrelvir and Ritonavir. Specifically, concentrations of ritonavir may be increased. Risk C: Monitor therapy
DexAMETHasone (Systemic): Nirmatrelvir and Ritonavir may increase the serum concentration of DexAMETHasone (Systemic). Risk C: Monitor therapy
Diamorphine: Nirmatrelvir and Ritonavir may decrease the serum concentration of Diamorphine. Risk C: Monitor therapy
DiazePAM: Nirmatrelvir and Ritonavir may increase the serum concentration of DiazePAM. Nirmatrelvir and Ritonavir may decrease the serum concentration of DiazePAM. Risk C: Monitor therapy
Dienogest: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Dienogest. Risk C: Monitor therapy
Digoxin: Nirmatrelvir and Ritonavir may increase the serum concentration of Digoxin. Management: Reduce the digoxin dose by approximately 30% to 50%, or reduce the dosing frequency, when these agents are combined. Monitor digoxin levels closely and adjust digoxin dose as needed. Risk D: Consider therapy modification
DilTIAZem: CYP3A4 Inhibitors (Strong) may increase the serum concentration of DilTIAZem. Risk C: Monitor therapy
Disopyramide: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Disopyramide. Risk C: Monitor therapy
DOCEtaxel: CYP3A4 Inhibitors (Strong) may increase the serum concentration of DOCEtaxel. Management: Avoid the concomitant use of docetaxel and strong CYP3A4 inhibitors when possible. If combined use is unavoidable, consider a 50% docetaxel dose reduction and monitor for increased docetaxel toxicities. Risk D: Consider therapy modification
Dofetilide: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Dofetilide. Risk C: Monitor therapy
Domperidone: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Domperidone. Risk X: Avoid combination
Doxazosin: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Doxazosin. Risk C: Monitor therapy
Doxercalciferol: CYP3A4 Inhibitors (Strong) may decrease serum concentrations of the active metabolite(s) of Doxercalciferol. Risk C: Monitor therapy
DOXOrubicin (Conventional): P-glycoprotein/ABCB1 Inhibitors may increase the serum concentration of DOXOrubicin (Conventional). Risk X: Avoid combination
DOXOrubicin (Liposomal): P-glycoprotein/ABCB1 Inhibitors may increase the serum concentration of DOXOrubicin (Liposomal). Risk C: Monitor therapy
DroNABinol: CYP3A4 Inhibitors (Strong) may increase the serum concentration of DroNABinol. Risk C: Monitor therapy
Dronedarone: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Dronedarone. Risk X: Avoid combination
Dutasteride: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Dutasteride. Risk C: Monitor therapy
Duvelisib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Duvelisib. Management: Reduce the dose of duvelisib to 15 mg twice a day when used together with a strong CYP3A4 inhibitor. Monitor closely for evidence of altered response to treatment. Risk D: Consider therapy modification
Dydrogesterone: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Dydrogesterone. Risk C: Monitor therapy
Ebastine: CYP3A4 Inhibitors (Strong) may increase serum concentrations of the active metabolite(s) of Ebastine. CYP3A4 Inhibitors (Strong) may increase the serum concentration of Ebastine. Risk C: Monitor therapy
Edoxaban: P-glycoprotein/ABCB1 Inhibitors may increase the serum concentration of Edoxaban. Risk C: Monitor therapy
Efavirenz: May enhance the adverse/toxic effect of Nirmatrelvir and Ritonavir. Efavirenz may decrease the serum concentration of Nirmatrelvir and Ritonavir. Specifically, efavirenz may decrease concentration of nirmatrelvir. Efavirenz may increase the serum concentration of Nirmatrelvir and Ritonavir. Specifically, efavirenz may increase concentration of ritonavir. Nirmatrelvir and Ritonavir may increase the serum concentration of Efavirenz. Risk C: Monitor therapy
Efonidipine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Efonidipine. Risk C: Monitor therapy
Elacestrant: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Elacestrant. Risk X: Avoid combination
Elagolix: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Elagolix. Management: Use of the elagolix 200 mg twice daily dose with a strong CYP3A4 inhibitor for longer than 1 month is not recommended. Limit combined use of the elagolix 150 mg once daily dose with a strong CYP3A4 inhibitor to a maximum of 6 months. Risk D: Consider therapy modification
Elagolix, Estradiol, and Norethindrone: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Elagolix, Estradiol, and Norethindrone. Elagolix, Estradiol, and Norethindrone may decrease the serum concentration of CYP3A4 Inhibitors (Strong). Specifically, concentrations of strong CYP3A4 inhibitors that are also CYP3A4 substrates may be decreased. Risk X: Avoid combination
Elbasvir and Grazoprevir: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Elbasvir and Grazoprevir. Management: Consider alternatives to this combination when possible. If combined, monitor for increased elbasvir/grazoprevir toxicities, including ALT elevations. Risk D: Consider therapy modification
Eletriptan: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Eletriptan. Risk X: Avoid combination
Elexacaftor, Tezacaftor, and Ivacaftor: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Elexacaftor, Tezacaftor, and Ivacaftor. Management: Administer elexacaftor/tezacaftor/ivacaftor in the morning, twice a week, 3 to 4 days apart, with no evening doses of ivacaftor alone. Specific dosing varies by age and weight. See full monograph for details. Risk D: Consider therapy modification
Eliglustat: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Eliglustat. Management: Reduce eliglustat dose to 84 mg daily in CYP2D6 EMs when used with strong CYP3A4 inhibitors. Use of strong CYP3A4 inhibitors is contraindicated in CYP2D6 IMs, PMs, or in CYP2D6 EMs who are also taking strong or moderate CYP2D6 inhibitors. Risk D: Consider therapy modification
Eluxadoline: Nirmatrelvir and Ritonavir may increase the serum concentration of Eluxadoline. Management: Decrease the eluxadoline dose to 75 mg twice daily and monitor patients for increased eluxadoline effects/toxicities (eg, impaired mental or physical abilities needed to drive a car or operate machinery, constipation, abdominal pain). Risk D: Consider therapy modification
Enfortumab Vedotin: Inhibitors of CYP3A4 (Strong) and P-glycoprotein may increase the serum concentration of Enfortumab Vedotin. Specifically, concentrations of the active monomethyl auristatin E (MMAE) component may be increased. Risk C: Monitor therapy
Entrectinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Entrectinib. Management: Avoid strong CYP3A4 inhibitors if possible. If needed, reduce entrectinib dose to 50 mg on alternating days if starting dose 200 mg; to 50 mg/day if starting dose 300 mg or 400 mg; to 100 mg/day if starting dose 600 mg. Risk D: Consider therapy modification
Eplerenone: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Eplerenone. Risk X: Avoid combination
Erdafitinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Erdafitinib. Management: Avoid concomitant use of erdafitinib and strong CYP3A4 inhibitors when possible. If combined, monitor closely for erdafitinib adverse reactions and consider dose modifications accordingly. Risk D: Consider therapy modification
Ergot Derivatives (Vasoconstrictive CYP3A4 Substrates): CYP3A4 Inhibitors (Strong) may increase the serum concentration of Ergot Derivatives (Vasoconstrictive CYP3A4 Substrates). Risk X: Avoid combination
Erlotinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Erlotinib. Management: Avoid use of this combination when possible. When the combination must be used, monitor the patient closely for the development of erlotinib-associated adverse reactions, and if such severe reactions occur, reduce the erlotinib dose (in 50 mg decrements). Risk D: Consider therapy modification
Erythromycin (Systemic): CYP3A4 Inhibitors (Strong) may increase the serum concentration of Erythromycin (Systemic). Management: Consider alternatives to this combination when possible. If combined, monitor for increased erythromycin effects and toxicities, including QTc interval prolongation. Risk D: Consider therapy modification
Estrogen Derivatives: Protease Inhibitors may decrease the serum concentration of Estrogen Derivatives. Protease Inhibitors may increase the serum concentration of Estrogen Derivatives. Risk C: Monitor therapy
Eszopiclone: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Eszopiclone. Management: Limit the eszopiclone dose to 2 mg daily when combined with strong CYP3A4 inhibitors and monitor for increased eszopiclone effects and toxicities (eg, somnolence, drowsiness, CNS depression). Risk D: Consider therapy modification
Etizolam: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Etizolam. Risk C: Monitor therapy
Etoposide: P-glycoprotein/ABCB1 Inhibitors may increase the serum concentration of Etoposide. Risk C: Monitor therapy
Etoposide Phosphate: P-glycoprotein/ABCB1 Inhibitors may increase the serum concentration of Etoposide Phosphate. Risk C: Monitor therapy
Etravirine: Nirmatrelvir and Ritonavir may decrease the serum concentration of Etravirine. Risk C: Monitor therapy
Everolimus: Inhibitors of CYP3A4 (Strong) and P-glycoprotein may increase the serum concentration of Everolimus. Risk X: Avoid combination
Evogliptin: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Evogliptin. Risk C: Monitor therapy
Fedratinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Fedratinib. Management: Consider alternatives when possible. If used together, decrease fedratinib dose to 200 mg/day. After the inhibitor is stopped, increase fedratinib to 300 mg/day for the first 2 weeks and then to 400 mg/day as tolerated. Risk D: Consider therapy modification
Felodipine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Felodipine. Management: Consider using lower felodipine doses when combined with strong CYP3A4 inhibitors. Monitor patients for increased felodipine effects and toxicities (eg, hypotension, edema) when combined. Risk D: Consider therapy modification
FentaNYL: CYP3A4 Inhibitors (Strong) may increase the serum concentration of FentaNYL. Management: Consider fentanyl dose reductions when combined with a strong CYP3A4 inhibitor. Monitor for respiratory depression and sedation. Upon discontinuation of a CYP3A4 inhibitor, consider a fentanyl dose increase; monitor for signs and symptoms of withdrawal. Risk D: Consider therapy modification
Fesoterodine: CYP3A4 Inhibitors (Strong) may increase serum concentrations of the active metabolite(s) of Fesoterodine. Management: Limit fesoterodine doses to 4 mg daily in patients who are also receiving strong CYP3A4 inhibitors. This combination is not recommended in pediatric patients weighing 25 kg up to 35 kg. Risk D: Consider therapy modification
Fexinidazole: CYP3A4 Inhibitors (Strong) may decrease serum concentrations of the active metabolite(s) of Fexinidazole. Management: Avoid use of fexinidazole and strong CYP3A4 inhibitors when possible. If combined, monitor for reduced fexinidazole efficacy. Risk D: Consider therapy modification
Finerenone: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Finerenone. Risk X: Avoid combination
Flecainide: Nirmatrelvir and Ritonavir may increase the serum concentration of Flecainide. Risk X: Avoid combination
Flibanserin: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Flibanserin. Management: Use of flibanserin with strong CYP3A4 inhibitors is contraindicated. If starting flibanserin, start 2 weeks after the last dose of the CYP3A4 inhibitor. If starting a CYP3A4 inhibitor, start 2 days after the last dose of flibanserin. Risk X: Avoid combination
Flunitrazepam: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Flunitrazepam. Risk C: Monitor therapy
Flurazepam: Nirmatrelvir and Ritonavir may increase the serum concentration of Flurazepam. Risk C: Monitor therapy
Fluticasone (Nasal): Nirmatrelvir and Ritonavir may increase the serum concentration of Fluticasone (Nasal). Management: Use of nasal fluticasone together with a strong CYP3A4 inhibitor is not recommended. Consider an alternative nasal corticosteroid, when possible. Risk D: Consider therapy modification
Fluticasone (Oral Inhalation): Nirmatrelvir and Ritonavir may increase the serum concentration of Fluticasone (Oral Inhalation). Risk C: Monitor therapy
Fosamprenavir: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Fosamprenavir. Risk C: Monitor therapy
Fosaprepitant: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Fosaprepitant. Risk X: Avoid combination
Fosphenytoin-Phenytoin: May decrease the serum concentration of Nirmatrelvir and Ritonavir. Nirmatrelvir and Ritonavir may decrease the serum concentration of Fosphenytoin-Phenytoin. Risk X: Avoid combination
Fostamatinib: CYP3A4 Inhibitors (Strong) may increase serum concentrations of the active metabolite(s) of Fostamatinib. Risk C: Monitor therapy
Fusidic Acid (Systemic): May increase the serum concentration of Nirmatrelvir and Ritonavir. Nirmatrelvir and Ritonavir may increase the serum concentration of Fusidic Acid (Systemic). Management: Avoid this combination if possible, due to the risk of increased concentrations of both agents which increases the risk of hepatotoxicity. If combined, monitor patients closely for adverse effects of both agents. Risk D: Consider therapy modification
Futibatinib: Inhibitors of CYP3A4 (Strong) and P-glycoprotein may increase the serum concentration of Futibatinib. Risk X: Avoid combination
Galantamine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Galantamine. Risk C: Monitor therapy
Garlic: May decrease the serum concentration of Protease Inhibitors. Risk X: Avoid combination
Gefitinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Gefitinib. Risk C: Monitor therapy
Gepirone: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Gepirone. Risk X: Avoid combination
Gilteritinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Gilteritinib. Management: Consider alternatives to the use of a strong CYP3A4 inhibitor with gilteritinib. If the combination cannot be avoided, monitor more closely for evidence of gilteritinib toxicities. Risk D: Consider therapy modification
Glasdegib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Glasdegib. Management: Consider alternatives to this combination when possible. If the combination must be used, monitor closely for evidence of QT interval prolongation and other adverse reactions to glasdegib. Risk D: Consider therapy modification
Glecaprevir and Pibrentasvir: Nirmatrelvir and Ritonavir may increase the serum concentration of Glecaprevir and Pibrentasvir. Risk X: Avoid combination
GuanFACINE: CYP3A4 Inhibitors (Strong) may increase the serum concentration of GuanFACINE. Management: Reduce the extended-release guanfacine dose 50% when combined with a strong CYP3A4 inhibitor. Monitor for increased guanfacine toxicities when these agents are combined. Risk D: Consider therapy modification
Halofantrine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Halofantrine. Management: Consider alternatives to this combination whenever possible. If combined, monitor closely for halofantrine toxicities, including QTc interval prolongation. Risk D: Consider therapy modification
Haloperidol: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Haloperidol. Risk C: Monitor therapy
Hormonal Contraceptives: Nirmatrelvir and Ritonavir may decrease the serum concentration of Hormonal Contraceptives. Specifically, nirmatrelvir and ritonavir may decrease concentrations of estrogens. Nirmatrelvir and Ritonavir may increase the serum concentration of Hormonal Contraceptives. Specifically, nirmatrelvir and ritonavir may increase concentrations of progestins. Management: Use additional nonhormonal forms of contraception (back-up method) when estrogen-containing hormonal contraceptives are combined with nirmatrelvir/ritonavir. Progestin-only contraceptives can be used without back-up, but monitor for progestin toxicities. Risk D: Consider therapy modification
HYDROcodone: CYP3A4 Inhibitors (Strong) may increase the serum concentration of HYDROcodone. Risk C: Monitor therapy
Hydrocortisone (Systemic): Nirmatrelvir and Ritonavir may increase the serum concentration of Hydrocortisone (Systemic). Risk C: Monitor therapy
Ibrexafungerp: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Ibrexafungerp. Management: Decrease the ibrexafungerp dose to 150 mg every 12 hours for 2 doses in patients receiving strong CYP3A4 inhibitors. Risk D: Consider therapy modification
Ibrutinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Ibrutinib. Management: Avoid concomitant use of ibrutinib and strong CYP3A4 inhibitors. If a strong CYP3A4 inhibitor must be used short-term (eg, anti-infectives for 7 days or less), interrupt ibrutinib therapy until the strong CYP3A4 inhibitor is discontinued. Risk X: Avoid combination
Idelalisib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Idelalisib. Management: Use alternative therapies that are not strong CYP3A4 inhibitors whenever possible. If unable to use alternative drugs, monitor patients more frequently for idelalisib toxicities. Risk D: Consider therapy modification
Ifosfamide: CYP3A4 Inhibitors (Strong) may decrease serum concentrations of the active metabolite(s) of Ifosfamide. Risk C: Monitor therapy
Iloperidone: CYP3A4 Inhibitors (Strong) may increase serum concentrations of the active metabolite(s) of Iloperidone. Specifically, concentrations of the metabolites P88 and P95 may be increased. CYP3A4 Inhibitors (Strong) may increase the serum concentration of Iloperidone. Management: Reduce iloperidone dose by half when administered with a strong CYP3A4 inhibitor. Risk D: Consider therapy modification
Imatinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Imatinib. Risk C: Monitor therapy
Imidafenacin: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Imidafenacin. Risk C: Monitor therapy
Indinavir: Nirmatrelvir and Ritonavir may enhance the adverse/toxic effect of Indinavir. Specifically, the risk for nephrolithiasis may be increased with this combination. Indinavir may increase the serum concentration of Nirmatrelvir and Ritonavir. Nirmatrelvir and Ritonavir may increase the serum concentration of Indinavir. Risk C: Monitor therapy
Infigratinib: CYP3A4 Inhibitors (Strong) may decrease serum concentrations of the active metabolite(s) of Infigratinib. CYP3A4 Inhibitors (Strong) may increase serum concentrations of the active metabolite(s) of Infigratinib. CYP3A4 Inhibitors (Strong) may increase the serum concentration of Infigratinib. Risk X: Avoid combination
Irinotecan Products: CYP3A4 Inhibitors (Strong) may increase serum concentrations of the active metabolite(s) of Irinotecan Products. Specifically, serum concentrations of SN-38 may be increased. Management: Avoid administration of strong CYP3A4 inhibitors during and within 1 week prior to irinotecan administration, unless no therapeutic alternatives to these agents exist. If combined, monitor closely for increased irinotecan toxicities. Risk D: Consider therapy modification
Isavuconazonium Sulfate: May increase the serum concentration of Nirmatrelvir and Ritonavir. Nirmatrelvir and Ritonavir may increase the serum concentration of Isavuconazonium Sulfate. Risk C: Monitor therapy
Isradipine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Isradipine. Risk C: Monitor therapy
Istradefylline: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Istradefylline. Management: Limit the maximum istradefylline dose to 20 mg daily when combined with strong CYP3A4 inhibitors and monitor for increased istradefylline effects/toxicities. Risk D: Consider therapy modification
Itraconazole: May increase the serum concentration of Nirmatrelvir and Ritonavir. Nirmatrelvir and Ritonavir may increase the serum concentration of Itraconazole. Management: Limit the adult maximum itraconazole dose to 200 mg/day in patients receiving nirmatrelvir/ritonavir. Risk D: Consider therapy modification
Ivabradine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Ivabradine. Risk X: Avoid combination
Ivacaftor: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Ivacaftor. Management: Ivacaftor dose reductions are required; consult full drug interaction monograph content for age- and weight-specific recommendations. Risk D: Consider therapy modification
Ivosidenib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Ivosidenib. Management: Avoid use of a strong CYP3A4 inhibitor with ivosidenib whenever possible. When combined use is required, reduce the ivosidenib dose to 250 mg once daily and monitor for increased ivosidenib toxicities, including QTc interval prolongation. Risk D: Consider therapy modification
Ixabepilone: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Ixabepilone. Management: Avoid use of ixabepilone and strong CYP3A4 inhibitors when possible. If combined, reduce the ixabepilone dose to 20 mg/m2. The previous ixabepilone dose can be resumed 1 week after discontinuation of the strong CYP3A4 inhibitor. Risk D: Consider therapy modification
Ketamine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Ketamine. Risk C: Monitor therapy
Ketoconazole (Systemic): May increase the serum concentration of Nirmatrelvir and Ritonavir. Nirmatrelvir and Ritonavir may increase the serum concentration of Ketoconazole (Systemic). Risk C: Monitor therapy
Lacidipine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Lacidipine. Risk C: Monitor therapy
LamoTRIgine: Nirmatrelvir and Ritonavir may decrease the serum concentration of LamoTRIgine. Risk C: Monitor therapy
Lapatinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Lapatinib. Management: Avoid use of lapatinib and strong CYP3A4 inhibitors when possible. If combined, a reduced lapatinib dose of 500 mg daily should be considered. The previous lapatinib dose can be resumed 1 week after discontinuation of the strong CYP3A4 inhibitor. Risk D: Consider therapy modification
Larotrectinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Larotrectinib. Management: Avoid use of strong CYP3A4 inhibitors with larotrectinib. If this combination cannot be avoided, reduce the larotrectinib dose by 50%. Increase to previous dose after stopping the inhibitor after a period of 3 to 5 times the inhibitor's half-life. Risk D: Consider therapy modification
Lefamulin: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Lefamulin. Management: Avoid concomitant use of lefamulin tablets and strong inhibitors of CYP3A4. Risk X: Avoid combination
Lemborexant: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Lemborexant. Risk X: Avoid combination
Leniolisib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Leniolisib. Risk X: Avoid combination
Lercanidipine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Lercanidipine. Risk X: Avoid combination
Letermovir: UGT1A1 Inducers may decrease the serum concentration of Letermovir. Risk X: Avoid combination
Leuprolide and Norethindrone: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Leuprolide and Norethindrone. Specifically, concentrations of norethindrone may increase. Risk C: Monitor therapy
Levamlodipine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Levamlodipine. Risk C: Monitor therapy
Levobupivacaine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Levobupivacaine. Risk C: Monitor therapy
Levoketoconazole: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Levoketoconazole. Risk X: Avoid combination
Levomethadone: Nirmatrelvir and Ritonavir may decrease the serum concentration of Levomethadone. Risk C: Monitor therapy
Levomilnacipran: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Levomilnacipran. Management: The dose of levomilnacipran should not exceed 80 mg once daily when used with strong CYP3A4 inhibitors. Risk D: Consider therapy modification
Lidocaine (Systemic): CYP3A4 Inhibitors (Strong) may increase the serum concentration of Lidocaine (Systemic). Risk C: Monitor therapy
Lomitapide: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Lomitapide. Risk X: Avoid combination
Lonafarnib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Lonafarnib. Risk X: Avoid combination
Lorlatinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Lorlatinib. Management: Avoid use of lorlatinib with strong CYP3A4 inhibitors. If the combination cannot be avoided, reduce the lorlatinib dose from 100 mg once daily to 75 mg once daily, or from 75 mg once daily to 50 mg once daily. Risk D: Consider therapy modification
Lovastatin: Nirmatrelvir and Ritonavir may increase the serum concentration of Lovastatin. Risk X: Avoid combination
Lumateperone: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Lumateperone. Management: Limit the lumateperone dose to 10.5 mg once daily when used with a strong CYP3A4 inhibitor. Risk D: Consider therapy modification
Lurasidone: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Lurasidone. Risk X: Avoid combination
Lurbinectedin: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Lurbinectedin. Management: Avoid concomitant use of lurbinectedin and strong CYP3A4 inhibitors. If coadministration with a strong CYP3A4 inhibitor cannot be avoided, reduce the lurbinectedin dose by 50%. Risk D: Consider therapy modification
Macitentan: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Macitentan. Risk X: Avoid combination
Manidipine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Manidipine. Management: Consider avoiding concomitant use of manidipine and strong CYP3A4 inhibitors. If combined, monitor closely for increased manidipine effects and toxicities. Manidipine dose reductions may be required. Risk D: Consider therapy modification
Maraviroc: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Maraviroc. Management: Reduce maraviroc to 150mg twice/day in adult and pediatrics weighing 40kg or more. See full interaction monograph for dose adjustments in pediatrics weighing 10 to less than 40kg. Do not use if CrCl less than 30mL/min or in those weighing less than 10 kg. Risk D: Consider therapy modification
Mavacamten: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Mavacamten. Risk X: Avoid combination
Mavorixafor: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Mavorixafor. Management: Decrease the mavorixafor dose to 200 mg daily if combined with strong CYP3A4 inhibitors. Risk D: Consider therapy modification
Mebendazole: Nirmatrelvir and Ritonavir may decrease the serum concentration of Mebendazole. Risk C: Monitor therapy
Mefloquine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Mefloquine. Risk C: Monitor therapy
Meperidine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Meperidine. Risk C: Monitor therapy
Meptazinol: Nirmatrelvir and Ritonavir may increase the serum concentration of Meptazinol. Risk X: Avoid combination
Methadone: Nirmatrelvir and Ritonavir may decrease the serum concentration of Methadone. Risk C: Monitor therapy
MethylPREDNISolone: Nirmatrelvir and Ritonavir may increase the serum concentration of MethylPREDNISolone. Risk C: Monitor therapy
Midazolam: Protease Inhibitors may increase the serum concentration of Midazolam. Management: Oral midazolam is contraindicated with protease inhibitors. Avoid use with nasal midazolam. Consider alternatives to use with other routes of midazolam (IV, IM) when possible. Consider use of lower midazolam doses if combined. Risk X: Avoid combination
Midostaurin: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Midostaurin. Management: Seek alternatives to the concomitant use of midostaurin and strong CYP3A4 inhibitors if possible. If concomitant use cannot be avoided, monitor patients for increased risk of adverse reactions. Risk D: Consider therapy modification
MiFEPRIStone: CYP3A4 Inhibitors (Strong) may increase the serum concentration of MiFEPRIStone. Management: For treatment of hyperglycemia in Cushing's syndrome, start mifepristone at 300 mg/day, may titrate to a maximum of 900 mg/day. If starting a strong CYP3A4 inhibitor and taking > 300 mg/day mifepristone, decrease the mifepristone dose by 300 mg/day. Risk D: Consider therapy modification
Mirodenafil: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Mirodenafil. Management: Consider using a lower dose of mirodenafil when used with strong CYP3A4 inhibitors. Monitor for increased mirodenafil effects/toxicities with the use of this combination. Risk D: Consider therapy modification
Mirtazapine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Mirtazapine. Risk C: Monitor therapy
Mirvetuximab Soravtansine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Mirvetuximab Soravtansine. Risk C: Monitor therapy
Mitapivat: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Mitapivat. Risk X: Avoid combination
Mobocertinib: CYP3A4 Inhibitors (Strong) may increase serum concentrations of the active metabolite(s) of Mobocertinib. CYP3A4 Inhibitors (Strong) may increase the serum concentration of Mobocertinib. Risk X: Avoid combination
Morphine (Systemic): P-glycoprotein/ABCB1 Inhibitors may increase the serum concentration of Morphine (Systemic). Risk C: Monitor therapy
Nadolol: P-glycoprotein/ABCB1 Inhibitors may increase the serum concentration of Nadolol. Risk C: Monitor therapy
Naldemedine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Naldemedine. Risk C: Monitor therapy
Nalfurafine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Nalfurafine. Risk C: Monitor therapy
Naloxegol: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Naloxegol. Risk X: Avoid combination
Neratinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Neratinib. Risk X: Avoid combination
NiCARdipine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of NiCARdipine. Risk C: Monitor therapy
NIFEdipine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of NIFEdipine. Management: Consider alternatives to this combination when possible. If combined, initiate nifedipine at the lowest dose available and monitor patients closely for increased nifedipine effects and toxicities (eg, hypotension, edema). Risk D: Consider therapy modification
Nilotinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Nilotinib. Management: Avoid if possible. If combination needed, decrease nilotinib to 300 mg once/day for patients with resistant or intolerant Ph+ CML or to 200 mg once/day for patients with newly diagnosed Ph+ CML in chronic phase. Risk D: Consider therapy modification
Nilvadipine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Nilvadipine. Risk C: Monitor therapy
NiMODipine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of NiMODipine. Risk X: Avoid combination
Nintedanib: Inhibitors of CYP3A4 (Strong) and P-glycoprotein may increase the serum concentration of Nintedanib. Risk C: Monitor therapy
Nirogacestat: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Nirogacestat. Risk X: Avoid combination
Nisoldipine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Nisoldipine. Risk X: Avoid combination
Nitrendipine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Nitrendipine. Risk C: Monitor therapy
OLANZapine: Nirmatrelvir and Ritonavir may decrease the serum concentration of OLANZapine. Risk C: Monitor therapy
Olaparib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Olaparib. Management: Avoid use of strong CYP3A4 inhibitors with olaparib, if possible. If such concurrent use cannot be avoided, the dose of olaparib tablets should be reduced to 100 mg twice daily and the dose of olaparib capsules should be reduced to 150 mg twice daily. Risk D: Consider therapy modification
Oliceridine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Oliceridine. Risk C: Monitor therapy
Olmutinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Olmutinib. Risk C: Monitor therapy
Omaveloxolone: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Omaveloxolone. Management: Avoid this combination if possible. If coadministration is required, decrease the omaveloxolone dose to 50 mg daily and monitor closely for adverse reactions. Discontinue coadministration if adverse reactions occur. Risk D: Consider therapy modification
Orelabrutinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Orelabrutinib. Risk X: Avoid combination
Orlistat: May decrease the serum concentration of Antiretroviral Agents. Risk C: Monitor therapy
Osilodrostat: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Osilodrostat. Management: Reduce osilodrostat dose by 50% during coadministration with a strong CYP3A4 inhibitor. Risk D: Consider therapy modification
Ospemifene: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Ospemifene. Risk C: Monitor therapy
OxyBUTYnin: CYP3A4 Inhibitors (Strong) may increase the serum concentration of OxyBUTYnin. Risk C: Monitor therapy
OxyCODONE: CYP3A4 Inhibitors (Strong) may enhance the adverse/toxic effect of OxyCODONE. CYP3A4 Inhibitors (Strong) may increase the serum concentration of OxyCODONE. Serum concentrations of the active metabolite oxymorphone may also be increased. Risk C: Monitor therapy
PACLitaxel (Conventional): CYP3A4 Inhibitors (Strong) may increase the serum concentration of PACLitaxel (Conventional). Risk C: Monitor therapy
PACLitaxel (Protein Bound): CYP3A4 Inhibitors (Strong) may increase the serum concentration of PACLitaxel (Protein Bound). Risk C: Monitor therapy
Pacritinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Pacritinib. Risk X: Avoid combination
Palbociclib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Palbociclib. Management: Avoid concurrent use of strong CYP3A4 inhibitors with palbociclib when possible. If the use of a strong CYP3A4 inhibitor cannot be avoided, decrease the palbociclib dose to 75 mg/day. Risk D: Consider therapy modification
Palovarotene: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Palovarotene. Risk X: Avoid combination
Panobinostat: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Panobinostat. Management: Reduce the panobinostat dose to 10 mg when it must be used with a strong CYP3A4 inhibitor. Monitor patient response to therapy closely for evidence of more severe adverse effects related to panobinostat therapy. Risk D: Consider therapy modification
Parecoxib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Parecoxib. Specifically, serum concentrations of the active moiety valdecoxib may be increased. Risk C: Monitor therapy
Paricalcitol: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Paricalcitol. Risk C: Monitor therapy
PAZOPanib: P-glycoprotein/ABCB1 Inhibitors may increase the serum concentration of PAZOPanib. Risk X: Avoid combination
Pemigatinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Pemigatinib. Management: If combined use cannot be avoided, reduce the pemigatinib dose from 13.5 mg daily to 9 mg daily, or from 9 mg daily to 4.5 mg daily. Resume prior pemigatinib dose after stopping the strong inhibitor once 3 half-lives of the inhibitor has passed. Risk D: Consider therapy modification
Pexidartinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Pexidartinib. Management: If combined use cannot be avoided, pexidartinib dose should be reduced as follows: reduce pexidartinib doses of 500 mg or 375 mg daily to 125 mg twice daily; reduce pexidartinib 250 mg daily to 125 mg once daily. Risk D: Consider therapy modification
PHENobarbital: Nirmatrelvir and Ritonavir may decrease the serum concentration of PHENobarbital. PHENobarbital may decrease the serum concentration of Nirmatrelvir and Ritonavir. Risk X: Avoid combination
Pimavanserin: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Pimavanserin. Management: Decrease the pimavanserin dose to 10 mg daily when combined with strong CYP3A4 inhibitors. Risk D: Consider therapy modification
Pimecrolimus: CYP3A4 Inhibitors (Strong) may decrease the metabolism of Pimecrolimus. Risk C: Monitor therapy
Pimozide: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Pimozide. Risk X: Avoid combination
Piperaquine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Piperaquine. Risk C: Monitor therapy
Pirtobrutinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Pirtobrutinib. Management: Avoid concomitant use when possible. If combined, reduce the pirtobrutinib dose by 50 mg. If current dose is 50 mg, interrupt pirtobrutinib treatment during strong CYP3A4 inhibitor use. Risk D: Consider therapy modification
Polatuzumab Vedotin: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Polatuzumab Vedotin. Exposure to unconjugated MMAE, the cytotoxic small molecule component of polatuzumab vedotin, may be increased. Risk C: Monitor therapy
PONATinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of PONATinib. Management: Avoid concomitant use if possible. If combined, reduce ponatinib dose as follows: If taking 45 mg, reduce to 30 mg; if taking 30 mg, reduce to 15 mg; if taking 15 mg, reduce to 10 mg. If taking 10 mg, avoid concomitant use with strong CYP3A4 inhibitors. Risk D: Consider therapy modification
Pralsetinib: Inhibitors of CYP3A4 (Strong) and P-glycoprotein may increase the serum concentration of Pralsetinib. Management: Avoid concomitant use if possible. If combined, reduce the pralsetinib dose. If taking 400 mg or 300 mg once daily, reduce to 200 mg once daily. If taking 200 mg once daily, reduce to 100 mg once daily. Risk D: Consider therapy modification
Prazepam: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Prazepam. Risk C: Monitor therapy
Praziquantel: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Praziquantel. Risk C: Monitor therapy
Primidone: May decrease serum concentrations of the active metabolite(s) of Nirmatrelvir and Ritonavir. Nirmatrelvir and Ritonavir may decrease the serum concentration of Primidone. Risk X: Avoid combination
Proguanil: Nirmatrelvir and Ritonavir may decrease the serum concentration of Proguanil. Risk C: Monitor therapy
Propafenone: Nirmatrelvir and Ritonavir may increase the serum concentration of Propafenone. Risk X: Avoid combination
QUEtiapine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of QUEtiapine. Management: In quetiapine treated patients, reduce quetiapine to one-sixth of original dose after starting a strong CYP3A4 inhibitor. In those on strong CYP3A4 inhibitors, start quetiapine at lowest dose and up-titrate as needed. Risk D: Consider therapy modification
QuiNIDine: Nirmatrelvir and Ritonavir may increase the serum concentration of QuiNIDine. Risk X: Avoid combination
Quinidine (Non-Therapeutic): CYP3A4 Inhibitors (Strong) may increase the serum concentration of Quinidine (Non-Therapeutic). Risk C: Monitor therapy
QuiNINE: May increase the serum concentration of Nirmatrelvir and Ritonavir. Nirmatrelvir and Ritonavir may decrease the serum concentration of QuiNINE. This effect has been seen with lopinavir/ritonavir. The effects of nirmatrelvir and ritonavir on quinine are unclear. Risk X: Avoid combination
Quizartinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Quizartinib. Management: If combination is necessary, reduce quizartinib dose as follows: from 53 mg daily to 26.5 mg daily; from 35.4 mg daily to 17.7 mg daily; from 26.5 mg daily to 17.7 mg daily. If taking 17.7 mg daily avoid quizartinib while on the strong CYP3A4 inhibitor. Risk D: Consider therapy modification
Radotinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Radotinib. Risk X: Avoid combination
Ramelteon: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Ramelteon. Risk C: Monitor therapy
Ranolazine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Ranolazine. Risk X: Avoid combination
Reboxetine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Reboxetine. Risk C: Monitor therapy
Red Yeast Rice: Nirmatrelvir and Ritonavir may increase the serum concentration of Red Yeast Rice. Risk X: Avoid combination
Regorafenib: CYP3A4 Inhibitors (Strong) may decrease serum concentrations of the active metabolite(s) of Regorafenib. CYP3A4 Inhibitors (Strong) may increase the serum concentration of Regorafenib. Risk X: Avoid combination
Relugolix: P-glycoprotein/ABCB1 Inhibitors may increase the serum concentration of Relugolix. Management: Avoid coadministration of relugolix with oral P-gp inhibitors whenever possible. If combined, take relugolix at least 6 hours prior to the P-gp inhibitor and monitor patients more frequently for adverse reactions. Risk D: Consider therapy modification
Relugolix, Estradiol, and Norethindrone: P-glycoprotein/ABCB1 Inhibitors may increase the serum concentration of Relugolix, Estradiol, and Norethindrone. Management: Avoid use of relugolix/estradiol/norethindrone with P-glycoprotein (P-gp) inhibitors. If concomitant use is unavoidable, relugolix/estradiol/norethindrone should be administered at least 6 hours before the P-gp inhibitor. Risk D: Consider therapy modification
Repaglinide: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Repaglinide. Risk C: Monitor therapy
Repotrectinib: P-glycoprotein/ABCB1 Inhibitors may increase the serum concentration of Repotrectinib. Risk X: Avoid combination
Retapamulin: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Retapamulin. Management: The use of retapamulin with strong CYP3A4 inhibitors is not recommended in patients less than 2 years old. No action is required in other populations. Risk C: Monitor therapy
Ribociclib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Ribociclib. Management: Avoid use of ribociclib with strong CYP3A4 inhibitors when possible; if combined use cannot be avoided, reduce ribociclib dose to 400 mg once daily. Risk D: Consider therapy modification
Rifabutin: Nirmatrelvir and Ritonavir may increase serum concentrations of the active metabolite(s) of Rifabutin. Nirmatrelvir and Ritonavir may increase the serum concentration of Rifabutin. Management: Decrease the rifabutin dose by at least 75%, to a maximum of 150 mg every other day or 3 times weekly, during coadministration with nirmatrelvir and ritonavir. Monitor for increased rifabutin adverse effects (eg, rash, urine discoloration, neutropenia). Risk D: Consider therapy modification
Rifapentine: May decrease the serum concentration of Nirmatrelvir and Ritonavir. Risk X: Avoid combination
RifAXIMin: P-glycoprotein/ABCB1 Inhibitors may increase the serum concentration of RifAXIMin. Risk C: Monitor therapy
Rilpivirine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Rilpivirine. Risk C: Monitor therapy
Rimegepant: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Rimegepant. Risk X: Avoid combination
Riociguat: Inhibitors of CYP3A4 (Strong) and P-glycoprotein may increase the serum concentration of Riociguat. Management: Consider a riociguat starting dose of 0.5 mg 3 times a day when initiating riociguat in patients receiving strong CYP3A4 and P-gp inhibitors. Monitor for hypotension when these agents are combined and reduce the riociguat dose as needed. Risk D: Consider therapy modification
Ripretinib: CYP3A4 Inhibitors (Strong) may increase serum concentrations of the active metabolite(s) of Ripretinib. CYP3A4 Inhibitors (Strong) may increase the serum concentration of Ripretinib. Risk C: Monitor therapy
RisperiDONE: P-glycoprotein/ABCB1 Inhibitors may increase the serum concentration of RisperiDONE. Risk C: Monitor therapy
Ritonavir: Nirmatrelvir and Ritonavir may increase the serum concentration of Ritonavir. Risk C: Monitor therapy
Rivaroxaban: Inhibitors of CYP3A4 (Strong) and P-glycoprotein may increase the serum concentration of Rivaroxaban. Risk X: Avoid combination
Roflumilast-Containing Products: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Roflumilast-Containing Products. Risk C: Monitor therapy
RomiDEPsin: CYP3A4 Inhibitors (Strong) may increase the serum concentration of RomiDEPsin. Risk C: Monitor therapy
Rosuvastatin: Nirmatrelvir and Ritonavir may increase the serum concentration of Rosuvastatin. Management: Consider temporarily discontinuing rosuvastatin during treatment with nirmatrelvir/ritonavir. It is not necessary to hold rosuvastatin either prior to or after completion of nirmatrelvir/ritonavir treatment. Risk D: Consider therapy modification
Rupatadine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Rupatadine. Risk X: Avoid combination
Ruxolitinib (Systemic): CYP3A4 Inhibitors (Strong) may increase the serum concentration of Ruxolitinib (Systemic). Management: This combination should be avoided under some circumstances; dose adjustments may be required in some circumstances and depend on the indication for ruxolitinib. See monograph for details. Risk D: Consider therapy modification
Ruxolitinib (Topical): CYP3A4 Inhibitors (Strong) may increase the serum concentration of Ruxolitinib (Topical). Risk X: Avoid combination
Sacituzumab Govitecan: UGT1A1 Inducers may decrease serum concentrations of the active metabolite(s) of Sacituzumab Govitecan. Specifically, concentrations of SN-38 may be decreased. Risk X: Avoid combination
Salmeterol: Nirmatrelvir and Ritonavir may increase the serum concentration of Salmeterol. Risk X: Avoid combination
SAXagliptin: CYP3A4 Inhibitors (Strong) may increase the serum concentration of SAXagliptin. Management: Limit the saxagliptin dose to 2.5 mg daily when combined with strong CYP3A4 inhibitors. When using the saxagliptin combination products saxagliptin/dapagliflozin or saxagliptin/dapagliflozin/metformin, avoid use with strong CYP3A4 inhibitors. Risk D: Consider therapy modification
Selpercatinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Selpercatinib. Management: Avoid combination if possible. If use is necessary, reduce selpercatinib dose as follows: from 120 mg twice/day to 40 mg twice/day, or from 160 mg twice/day to 80 mg twice/day. Risk D: Consider therapy modification
Selumetinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Selumetinib. Management: Avoid concomitant use when possible. If combined, selumetinib dose reductions are recommended and vary based on body surface area and selumetinib dose. For details, see the full drug interaction monograph or selumetinib prescribing information. Risk D: Consider therapy modification
Sertindole: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Sertindole. Risk X: Avoid combination
Sibutramine: CYP3A4 Inhibitors (Strong) may increase serum concentrations of the active metabolite(s) of Sibutramine. CYP3A4 Inhibitors (Strong) may increase the serum concentration of Sibutramine. Risk C: Monitor therapy
Sildenafil: Protease Inhibitors may increase the serum concentration of Sildenafil. Management: Use of protease inhibitors and sildenafil for the treatment of PAH is contraindicated. If using sildenafil for the treatment of erectile dysfunction, limit the sildenafil dose to 25 mg and do not use more frequently than every 48 hours. Risk D: Consider therapy modification
Silodosin: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Silodosin. Risk X: Avoid combination
Simeprevir: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Simeprevir. Risk X: Avoid combination
Simvastatin: Nirmatrelvir and Ritonavir may increase the serum concentration of Simvastatin. Management: Discontinue simvastatin at least 12 hours prior to initiating nirmatrelvir and ritonavir, and do not restart simvastatin until 5 days after completing nirmatrelvir and ritonavir treatment. Risk X: Avoid combination
Sirolimus (Conventional): Nirmatrelvir and Ritonavir may increase the serum concentration of Sirolimus (Conventional). Management: Consider avoiding this combination, if possible, through use of alternative anti-COVID-19 therapy. If combined, hold sirolimus during nirmatrelvir/ritonavir treatment and for at least 2 to 3 days after completion. Monitor sirolimus levels closely. Risk D: Consider therapy modification
Sirolimus (Protein Bound): CYP3A4 Inhibitors (Strong) may increase the serum concentration of Sirolimus (Protein Bound). Risk X: Avoid combination
Sirolimus (Topical): CYP3A4 Inhibitors (Strong) may increase the serum concentration of Sirolimus (Topical). Risk C: Monitor therapy
Solifenacin: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Solifenacin. Management: Limit adult solifenacin doses to 5 mg daily and limit doses in pediatric patients to the recommended weight-based starting dose (and do not increase the dose) when combined with strong CYP3A4 inhibitors. Risk D: Consider therapy modification
Sonidegib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Sonidegib. Risk X: Avoid combination
Sparsentan: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Sparsentan. Risk X: Avoid combination
St John's Wort: May decrease the serum concentration of Nirmatrelvir and Ritonavir. Risk X: Avoid combination
SUFentanil: CYP3A4 Inhibitors (Strong) may increase the serum concentration of SUFentanil. Management: If a strong CYP3A4 inhibitor is initiated in a patient on sufentanil, consider a sufentanil dose reduction and monitor for increased sufentanil effects and toxicities (eg, respiratory depression). Risk D: Consider therapy modification
SUNItinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of SUNItinib. Management: Avoid when possible. If combined, decrease sunitinib dose to a minimum of 37.5 mg daily when treating GIST or RCC. Decrease sunitinib dose to a minimum of 25 mg daily when treating PNET. Monitor patients for both reduced efficacy and increased toxicities. Risk D: Consider therapy modification
Suvorexant: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Suvorexant. Risk X: Avoid combination
Tacrolimus (Systemic): Nirmatrelvir and Ritonavir may increase the serum concentration of Tacrolimus (Systemic). Management: Consider avoiding this combination, if possible, through use of alternative anti-COVID-19 therapy. If combined, hold tacrolimus during nirmatrelvir/ritonavir treatment and for at least 2 to 3 days after completion. Monitor tacrolimus levels closely. Risk D: Consider therapy modification
Tacrolimus (Topical): CYP3A4 Inhibitors (Strong) may increase the serum concentration of Tacrolimus (Topical). Risk C: Monitor therapy
Tadalafil: Nirmatrelvir and Ritonavir may increase the serum concentration of Tadalafil. Management: In patients treated for pulmonary arterial hypertension avoid initiating nirmatrelvir and ritonavir in patients taking tadalafil. For ED or BPH treatment, decrease tadalafil max dose and frequency. See full monograph for details. Risk D: Consider therapy modification
Talazoparib: P-glycoprotein/ABCB1 Inhibitors may increase the serum concentration of Talazoparib. Risk C: Monitor therapy
Tamsulosin: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Tamsulosin. Risk X: Avoid combination
Tasimelteon: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Tasimelteon. Risk C: Monitor therapy
Tazemetostat: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Tazemetostat. Risk X: Avoid combination
Tegaserod (Withdrawn from US Market): P-glycoprotein/ABCB1 Inhibitors may increase the serum concentration of Tegaserod (Withdrawn from US Market). Risk C: Monitor therapy
Temsirolimus: CYP3A4 Inhibitors (Strong) may increase serum concentrations of the active metabolite(s) of Temsirolimus. Specifically, concentrations of sirolimus may be increased. Management: Avoid concomitant use of temsirolimus and strong CYP3A4 inhibitors. If coadministration is unavoidable, decrease temsirolimus dose to 12.5 mg per week. Resume previous temsirolimus dose 1 week after discontinuation of the strong CYP3A4 inhibitor. Risk D: Consider therapy modification
Teniposide: P-glycoprotein/ABCB1 Inhibitors may increase the serum concentration of Teniposide. Risk C: Monitor therapy
Tenofovir Alafenamide: Nirmatrelvir and Ritonavir may increase the serum concentration of Tenofovir Alafenamide. Risk C: Monitor therapy
Tenofovir Disoproxil Fumarate: P-glycoprotein/ABCB1 Inhibitors may increase the serum concentration of Tenofovir Disoproxil Fumarate. Risk C: Monitor therapy
Terfenadine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Terfenadine. Risk X: Avoid combination
Tetrahydrocannabinol: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Tetrahydrocannabinol. Risk C: Monitor therapy
Tetrahydrocannabinol and Cannabidiol: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Tetrahydrocannabinol and Cannabidiol. Risk C: Monitor therapy
Tezacaftor and Ivacaftor: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Tezacaftor and Ivacaftor. Management: If combined with strong CYP3A4 inhibitors, tezacaftor/ivacaftor should be administered in the morning, twice a week, approximately 3 to 4 days apart. Tezacaftor/ivacaftor dose depends on age and weight; see full Lexi-Interact monograph for details. Risk D: Consider therapy modification
Theophylline Derivatives: Nirmatrelvir and Ritonavir may decrease the serum concentration of Theophylline Derivatives. Risk C: Monitor therapy
Thioridazine: CYP2D6 Inhibitors (Weak) may increase the serum concentration of Thioridazine. Management: Consider avoiding concomitant use of thioridazine and weak CYP2D6 inhibitors. If combined, monitor closely for QTc interval prolongation and arrhythmias. Some weak CYP2D6 inhibitors list use with thioridazine as a contraindication. Risk D: Consider therapy modification
Thiotepa: CYP3A4 Inhibitors (Strong) may decrease serum concentrations of the active metabolite(s) of Thiotepa. CYP3A4 Inhibitors (Strong) may increase the serum concentration of Thiotepa. Management: Avoid coadministration of thiotepa and strong CYP3A4 inhibitors. If concomitant use cannot be avoided, monitor for thiotepa adverse effects and decreased efficacy. Risk D: Consider therapy modification
Thyroid Products: Nirmatrelvir and Ritonavir may diminish the therapeutic effect of Thyroid Products. Risk C: Monitor therapy
Ticagrelor: CYP3A4 Inhibitors (Strong) may decrease serum concentrations of the active metabolite(s) of Ticagrelor. CYP3A4 Inhibitors (Strong) may increase the serum concentration of Ticagrelor. Risk X: Avoid combination
Tisotumab Vedotin: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Tisotumab Vedotin. Specifically, concentrations of the active monomethyl auristatin E (MMAE) component may be increased. Risk C: Monitor therapy
Tofacitinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Tofacitinib. Management: Tofacitinib dose reductions are recommended when combined with strong CYP3A4 inhibitors. Recommended dose adjustments vary by tofacitinib formulation and therapeutic indication. See full Lexi Interact monograph for details. Risk D: Consider therapy modification
Tolterodine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Tolterodine. Management: The maximum recommended dose of tolterodine is 2 mg per day (1 mg twice daily for immediate-release tablets or 2 mg daily for extended-release capsules) when used together with a strong CYP3A4 inhibitor. Risk D: Consider therapy modification
Tolvaptan: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Tolvaptan. Risk X: Avoid combination
Topotecan: P-glycoprotein/ABCB1 Inhibitors may increase the serum concentration of Topotecan. Risk X: Avoid combination
Toremifene: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Toremifene. Management: Use of toremifene with strong CYP3A4 inhibitors should be avoided if possible. If coadministration is necessary, monitor for increased toremifene toxicities, including QTc interval prolongation. Risk D: Consider therapy modification
Trabectedin: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Trabectedin. Risk X: Avoid combination
TraMADol: CYP3A4 Inhibitors (Strong) may increase serum concentrations of the active metabolite(s) of TraMADol. CYP3A4 Inhibitors (Strong) may increase the serum concentration of TraMADol. Risk C: Monitor therapy
TraZODone: CYP3A4 Inhibitors (Strong) may increase the serum concentration of TraZODone. Management: Consider the use of a lower trazodone dose and monitor for increased trazodone effects (eg, sedation, QTc prolongation) if combined with strong CYP3A4 inhibitors. Risk D: Consider therapy modification
Tretinoin (Systemic): CYP3A4 Inhibitors (Strong) may increase the serum concentration of Tretinoin (Systemic). Risk C: Monitor therapy
Triamcinolone (Systemic): Nirmatrelvir and Ritonavir may increase the serum concentration of Triamcinolone (Systemic). Risk C: Monitor therapy
Triazolam: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Triazolam. Risk X: Avoid combination
Ubrogepant: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Ubrogepant. Risk X: Avoid combination
Udenafil: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Udenafil. Risk X: Avoid combination
Ulipristal: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Ulipristal. Risk C: Monitor therapy
Upadacitinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Upadacitinib. Management: Upadacitinib dose adjustments are often needed when combined with strong CYP3A4 inhibitors. Specific adjustments vary based on upadacitinib indication. See full interact monograph for details. Risk D: Consider therapy modification
Valbenazine: CYP3A4 Inhibitors (Strong) may increase serum concentrations of the active metabolite(s) of Valbenazine. CYP3A4 Inhibitors (Strong) may increase the serum concentration of Valbenazine. Management: Reduce the valbenazine dose to 40 mg daily when combined with strong CYP3A4 inhibitors. Risk D: Consider therapy modification
Valproate Products: Protease Inhibitors may decrease the serum concentration of Valproate Products. Risk C: Monitor therapy
Vamorolone: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Vamorolone. Management: Reduce the vamorolone dose to 4 mg/kg daily, with a maximum dose of 200 mg daily for patients weighing over 50 kg, when combined with strong CYP3A4 inhibitors. Risk D: Consider therapy modification
Vardenafil: Nirmatrelvir and Ritonavir may increase the serum concentration of Vardenafil. Management: Limit the dose of vardenafil tablets to a single 2.5 mg dose within a 72-hour period if combined with nirmatrelvir/ritonavir. Avoid concomitant use of vardenafil orally disintegrating tablets and nirmatrelvir/ritonavir. Risk D: Consider therapy modification
Vemurafenib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Vemurafenib. Management: Avoid concurrent use of vemurafenib with strong CYP3A4 inhibitors when possible. If concomitant use is unavoidable, consider a vemurafenib dose reduction if clinically indicated. Risk D: Consider therapy modification
Venetoclax: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Venetoclax. Management: Coadministration is contraindicated during venetoclax initiation and ramp-up in CLL/SLL patients. Reduced venetoclax doses are required during ramp-up for patients with AML, and all maintenance therapy. See full Lexi Interact monograph for details. Risk D: Consider therapy modification
Verapamil: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Verapamil. Risk C: Monitor therapy
Vilanterol: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Vilanterol. Risk C: Monitor therapy
Vilazodone: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Vilazodone. Management: Limit the maximum vilazodone dose to 20 mg daily in patients receiving strong CYP3A4 inhibitors. The original vilazodone dose can be resumed following discontinuation of the strong CYP3A4 inhibitor. Risk D: Consider therapy modification
VinBLAStine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of VinBLAStine. Risk C: Monitor therapy
VinCRIStine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of VinCRIStine. Management: Seek alternatives to this combination when possible. If combined, monitor closely for vincristine toxicities (eg, neurotoxicity, gastrointestinal toxicity, myelosuppression). Risk D: Consider therapy modification
VinCRIStine (Liposomal): CYP3A4 Inhibitors (Strong) may increase the serum concentration of VinCRIStine (Liposomal). Risk X: Avoid combination
Vindesine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Vindesine. Risk C: Monitor therapy
Vinflunine: CYP3A4 Inhibitors (Strong) may increase serum concentrations of the active metabolite(s) of Vinflunine. CYP3A4 Inhibitors (Strong) may increase the serum concentration of Vinflunine. Risk X: Avoid combination
Vinorelbine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Vinorelbine. Risk C: Monitor therapy
Vitamin K Antagonists (eg, warfarin): Nirmatrelvir and Ritonavir may decrease the serum concentration of Vitamin K Antagonists. Nirmatrelvir and Ritonavir may increase the serum concentration of Vitamin K Antagonists. Risk C: Monitor therapy
Voclosporin: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Voclosporin. Risk X: Avoid combination
Vorapaxar: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Vorapaxar. Risk X: Avoid combination
Voriconazole: Nirmatrelvir and Ritonavir may decrease the serum concentration of Voriconazole. Nirmatrelvir and Ritonavir may increase the serum concentration of Voriconazole. Management: Consider avoiding this combination if possible. NIH COVID-19 treatment guidelines state voriconazole may be continued in patients treated with nirmatrelvir and ritonavir, but patients should be monitored for adverse effects. Risk D: Consider therapy modification
Zanubrutinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Zanubrutinib. Management: Decrease the zanubrutinib dose to 80 mg once daily during coadministration with a strong CYP3A4 inhibitor. Further dose adjustments may be required for zanubrutinib toxicities, refer to prescribing information for details. Risk D: Consider therapy modification
Zidovudine: Nirmatrelvir and Ritonavir may decrease the serum concentration of Zidovudine. Risk C: Monitor therapy
Ziprasidone: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Ziprasidone. Risk C: Monitor therapy
Zolpidem: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Zolpidem. Risk C: Monitor therapy
Zopiclone: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Zopiclone. Management: If coadministered with strong CYP3A4 inhibitors, initiate zopiclone at 3.75 mg in adults, with a maximum dose of 5 mg. Monitor for zopiclone toxicity (eg, drowsiness, confusion, lethargy, ataxia, respiratory depression). Risk D: Consider therapy modification
Zuranolone: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Zuranolone. Management: Reduce the zuranolone dose to 30 mg once daily when used concomitantly with a strong CYP3A4 inhibitor. Risk D: Consider therapy modification
Ritonavir may reduce the efficacy of combination hormonal contraceptives (CHCs). Patients using CHCs should use an effective alternative contraceptive or an additional barrier contraceptive during treatment with ritonavir. Consult drug interactions database for more detailed information specific to use of ritonavir and contraceptives.
Both nirmatrelvir (Chuang 2023) and ritonavir cross the placenta.
Outcome data following maternal use of ritonavir-boosted nirmatrelvir during pregnancy are limited (Garmeau 2022; Lin 2023a; Lin 2023b; Loza 2022; Toure 2023; Zhuang 2023). Ritonavir has been highly studied in pregnant patients (Chourasia 2023); refer to the Ritonavir monograph for information related to ritonavir and pregnancy.
The risk of severe morbidity and mortality from COVID-19 infection is increased in symptomatic pregnant patients compared to nonpregnant patients. Pregnant and recently pregnant patients with moderate or severe infection are at increased risk of complications such as hypertensive disorders of pregnancy, postpartum hemorrhage, or other infections compared to pregnant patients without COVID-19. Symptomatic pregnant patients may require ICU admission, mechanical ventilation, or ventilatory support (ECMO). Other adverse pregnancy outcomes include preterm birth and stillbirth. The risk of coagulopathy, cesarean delivery, and maternal death may be increased; neonates have an increased risk for NICU admission. Maternal age and comorbidities such as diabetes, hypertension, lung disease, and obesity may also increase the risk of severe illness in pregnant and recently pregnant patients (ACOG 2023; NIH 2023).
In general, the treatment of COVID-19 infection during pregnancy is the same as in nonpregnant patients. However, because data for most therapeutic agents in pregnant patients are limited, treatment options should be evaluated as part of a shared decision-making process (NIH 2023). Pregnancy is a risk factor for severe COVID-19. The use of ritonavir-boosted nirmatrelvir is recommended and can be initiated in nonhospitalized pregnant patients who test positive for COVID-19 or are highly suspected of being positive. Evaluate potential drug interactions prior to prescribing (ACOG 2023; NIH 2023). Information related to the treatment of COVID-19 during pregnancy continues to emerge; refer to current guidelines for the treatment of pregnant patients.
Data collection to monitor maternal and infant outcomes following exposure to COVID-19 during pregnancy is ongoing. Health care providers are encouraged to enroll patients exposed to COVID-19 during pregnancy in the Organization of Teratology Information Specialists pregnancy registry (1-877-311-8972; https://mothertobaby.org/join-study/).
Ritonavir is present in breast milk; excretion of nirmatrelvir is unknown.
Outcome data following the use of ritonavir-boosted nirmatrelvir in lactating patients are limited (Lin 2023a).
Breast milk has not been found to be a source of COVID-19 infection and maternal infection is not a contraindication to breastfeeding. The decision to breastfeed during treatment for COVID-19 should be evaluated as part of a shared decision-making process. Breastfeeding can continue if ritonavir-boosted nirmatrelvir is needed for the management of COVID-19. However, lactating patients with COVID-19 infection can transmit the virus through respiratory droplets and all precautions should be taken to avoid spreading the virus to the infant (eg, hand hygiene, mask wearing); alternatively, breast milk can be expressed and fed to the infant by someone without confirmed or suspected COVID-19 (ACOG 2023; NIH 2023).
Information related to COVID-19 and breastfeeding is available from the World Health Organization (https://www.who.int/news/item/28-04-2020-new-faqs-address-healthcare-workers-questions-on-breastfeeding-and-covid-19).
Nirmatrelvir is a peptidomimetic inhibitor of the SARS-CoV-2 main protease (Mpro; also known as 3C-like protease or nsp5 protease); inhibition of Mpro prevents processing of polyprotein precursors, resulting in inhibition of viral replication. Ritonavir is a pharmacokinetic enhancer with no activity against SARS-CoV-2 Mpro. Ritonavir inhibits CYP3A-mediated metabolism of nirmatrelvir, resulting in increased nirmatrelvir plasma concentrations.
Distribution: Vz/F: Nirmatrelvir (when given with ritonavir): 104.7 L; Ritonavir: 112.4 L.
Protein binding: Nirmatrelvir (when given with ritonavir): 69%; Ritonavir: 98% to 99%.
Metabolism: Nirmatrelvir (when given with ritonavir): Minimal; Ritonavir: Hepatic via CYP3A4 (major) and CYP2D6 (minor).
Half-life elimination: Nirmatrelvir (when given with ritonavir): 6.05 hours; Ritonavir: 6.15 hours.
Time to peak: Nirmatrelvir (when given with ritonavir): 3 hours; Ritonavir: 3.98 hours.
Excretion: Nirmatrelvir (when given with ritonavir): Feces (27.5%); urine (55%); Ritonavir: Feces (86.4%); urine (3.5%).
Altered kidney function: Cmax and AUC were 30% and 24% higher in subjects with eGFR ≥60 to <90 mL/minute, 38% and 87% higher in subjects with eGFR ≥30 to <60 mL/minute, and 48% and 204% higher in subjects with eGFR <30 mL/minute.
Pediatric: Clinical trials have not been performed; serum exposures in patients ≥12 years of age and weighing ≥40 kg are expected to be similar to those observed in adults (FDA 2023).
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