Version July 2025
Note: Dosage expressed as chloroquine phosphate. Chloroquine phosphate 16.7 mg is equivalent to 10 mg chloroquine base.
Malaria, prophylaxis: Note: For use only in areas with chloroquine-susceptible malaria (Ref).
Infants, Children, and Adolescents: Oral: 8.3 mg/kg chloroquine phosphate once weekly on the same day each week; maximum dose: 500 mg chloroquine phosphate/dose. Begin 1 to 2 weeks before travel to malarious area; continue while in malarious area and for 4 weeks after leaving the area (Ref).
Malaria, uncomplicated, treatment: Infants, Children, and Adolescents: Oral: Initial: 16.7 mg/kg/dose chloroquine phosphate once (maximum initial dose: 1,000 mg chloroquine phosphate); followed by 8.3 mg/kg/dose chloroquine phosphate (maximum dose: 500 mg chloroquine phosphate/dose) administered at 6, 24, and 48 hours after initial dose for a total of 4 doses (Ref). For infection caused by Plasmodium vivax or Plasmodium ovale, use in combination with appropriate antirelapse treatment (eg, primaquine) (Ref).
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: Infants, Children, and Adolescents: Oral:
Mild to severe impairment: There are no dosage adjustments provided in the manufacturer's labeling; use with caution; based on adult information, dose adjustment may be necessary with chronic use in patients with GFR <10 mL/minute.
Hemodialysis: There are no dosage adjustments provided in the manufacturer's labeling; use with caution. Based on adult information, dose adjustment may be necessary with chronic use.
Peritoneal dialysis: There are no dosage adjustments provided in the manufacturer's labeling; use with caution. Based on adult information, dose adjustment may be necessary with chronic use.
Continuous renal replacement therapy (CRRT): There are no dosage adjustments provided in the manufacturer's labeling; use with caution. Based on adult information, no dose adjustments necessary.
There are no dosage adjustments provided in the manufacturer’s labeling; use with caution.
(For additional information see "Chloroquine: Drug information")
Note: Dosages are expressed as chloroquine phosphate. Each 250 mg of chloroquine phosphate is equivalent to 150 mg of chloroquine base.
Amebiasis, extraintestinal: Oral: 1 g (600 mg base) daily for 2 days followed by 500 mg daily (300 mg base) for at least 2 to 3 weeks; may be combined with an intestinal amebicide.
Discoid lupus erythematosus (off-label use): Oral: Not considered first-line agent (Ref). Due to the risk of retinal toxicity, do not exceed a daily dose of 2.3 mg/kg/day using actual body weight; intermediate doses may be obtained by splitting tablets or eliminating a tablet on certain days of the week (Ref).
Malaria, prophylaxis: Oral: 500 mg (300 mg base) once weekly on the same day each week; begin 1 to 2 weeks prior to exposure; continue while in endemic area and for 4 weeks after leaving endemic area. Note: For use only in areas with chloroquine-sensitive malaria (Ref).
Malaria, uncomplicated, treatment: Oral: 1 g (600 mg base) on day 1, followed by 500 mg (300 mg base) 6-, 24-, and 48 hours after first dose (Ref) or 16.7 mg/kg (10 mg/kg base) as a single dose on day 1 and day 2, followed by 8.3 mg/kg (5 mg/kg base) as a single dose on day 3 (for a total dose of 41.7 mg/kg [25 mg/kg base]) (Ref). Note: For treatment of chloroquine-sensitive P. vivax and P. ovale, concomitant therapy with an 8-aminoquinoline (eg, primaquine, tafenoquine) is necessary (Ref).
Dosage adjustment for concomitant therapy: Significant drug interactions exist, requiring dose/frequency adjustment or avoidance. Consult drug interactions database for more information.
The renal dosing recommendations are based upon the best available evidence and clinical expertise. Senior Editorial Team: Bruce Mueller, PharmD, FCCP, FASN, FNKF; Jason A. Roberts, PhD, BPharm (Hons), B App Sc, FSHP, FISAC; Michael Heung, MD, MS.
GFR ≥10 mL/minute: No dosage adjustment necessary.
GFR <10 mL/minute: No dosage adjustment necessary with short-term use at recommended doses and durations (eg, malaria treatment) (Ref); use with caution. With prolonged use (eg, lupus erythematosus), administer 50% of dose (Ref).
Hemodialysis: No dosage adjustment necessary with short-term use at recommended doses and durations (eg, malaria treatment) (Ref); use with caution. With prolonged use (eg, lupus erythematosus), administer 50% of dose (Ref).
Peritoneal dialysis: No dosage adjustment necessary with short-term use at recommended doses and durations (eg, malaria treatment) (Ref); use with caution. With prolonged use (eg, lupus erythematosus), administer 50% of dose (Ref).
CRRT: No dosage adjustment necessary (Ref).
There are no dosage adjustments provided in the manufacturer's labeling; use with caution.
The following adverse drug reactions and incidences are derived from product labeling unless otherwise specified.
Frequency not defined:
Cardiovascular: Atrioventricular block, bundle branch block, cardiac arrhythmia, cardiac failure, cardiomyopathy, ECG changes (including flattened T wave on ECG, inversion T wave on ECG, prolonged QT interval on ECG, widened QRS complex on ECG), hypotension, torsades de pointes, ventricular fibrillation, ventricular tachycardia
Dermatologic: Alopecia, bleaching of hair, blue-gray skin pigmentation (oral mucosa and hard palate, nails, and skin [Gallo 2009; Horta-Bass 2018; Manger 2017]), erythema multiforme, exacerbation of psoriasis, exfoliative dermatitis, lichen planus, pleomorphic rash, pruritus, skin photosensitivity, Stevens-Johnson syndrome, toxic epidermal necrolysis, urticaria
Endocrine & metabolic: Exacerbation of porphyria, severe hypoglycemia
Gastrointestinal: Abdominal cramps, anorexia, diarrhea, nausea, vomiting
Hematologic & oncologic: Agranulocytosis (reversible), aplastic anemia, hemolytic anemia (in G6PD-deficient patients), neutropenia, pancytopenia, thrombocytopenia
Hepatic: Hepatitis, increased liver enzymes
Hypersensitivity: Anaphylaxis, angioedema
Immunologic: Drug reaction with eosinophilia and systemic symptoms
Nervous system: Agitation, anxiety, confusion, decreased deep tendon reflex, delirium, depression, extrapyramidal reaction (dystonia, dyskinesia, protrusion of the tongue, torticollis), hallucination, headache, insomnia, personality changes, polyneuropathy, psychosis, seizure, sensorimotor neuropathy, sensorineural hearing loss, suicidal tendencies
Neuromuscular & skeletal: Asthenia, myopathy, neuromuscular disease, proximal myopathy
Ophthalmic: Accommodation disturbances, blurred vision, corneal opacity (reversible), macular degeneration (may be irreversible), maculopathy (may be irreversible), night blindness, retinal pigment changes (bull’s eye appearance), retinopathy (including irreversible changes in long-term or high-dose therapy), transient scotomata, visual field defect (paracentral scotomas)
Otic: Hearing loss (risk increased in patients with preexisting auditory damage), tinnitus
Postmarketing:
Hepatic: Hepatic impairment (FDA Safety Alert, April 1, 2020)
Renal: Renal insufficiency (FDA Safety Alert, April 1, 2020)
Hypersensitivity to chloroquine, 4-aminoquinoline compounds, or any component of the formulation; the presence of retinal or visual field changes of any etiology (when used for indications other than acute malaria)
Concerns related to adverse effects:
• Cardiovascular effects: Cases of cardiomyopathy resulting in cardiac failure (sometimes fatal) have been reported during long term therapy at high doses. Monitor for signs and symptoms of cardiomyopathy; discontinue if cardiomyopathy develops. Consider chronic toxicity and discontinue chloroquine if conduction disorders (bundle branch block/AV block) are diagnosed. QT prolongation, torsade de pointes, and ventricular arrhythmias (some fatal) have been reported; risk is increased with high doses. Use with caution in patients with cardiac disease, history of ventricular arrhythmias, uncorrected hypokalemia and/or hypomagnesemia, or bradycardia, and during concomitant administration with QT interval prolonging agents due to potential for QT prolongation. In a scientific statement from the American Heart Association, chloroquine has been determined to be an agent that may either cause direct myocardial toxicity or exacerbate underlying myocardial dysfunction (magnitude: major) (AHA [Page 2016]).
• Extrapyramidal effects: Acute extrapyramidal disorders may occur, usually resolving after discontinuation of therapy and/or symptomatic treatment.
• Hematologic effects: Rare hematologic reactions including reversible agranulocytosis, aplastic anemia, neutropenia, pancytopenia, and thrombocytopenia have been reported; monitor CBC during prolonged therapy. Consider discontinuation if severe blood disorders occur that are unrelated to disease.
• Hypoglycemia: Severe hypoglycemia, including loss of consciousness, has been reported in patients treated with or without antidiabetic agents. Counsel patients about risk of hypoglycemia and associated signs and symptoms.
• Neuromuscular effects: Skeletal muscle myopathy or neuromyopathy, leading to progressive weakness and atrophy of proximal muscle groups have been reported; muscle strength (especially proximal muscles) should be assessed periodically during prolonged therapy; discontinue therapy if weakness occurs.
• Retinal toxicity: Retinal toxicity, potentially causing irreversible retinopathy, is predominantly associated with high daily doses and a duration of >5 years of use of chloroquine or hydroxychloroquine in the treatment of rheumatic diseases. Other major risk factors include concurrent tamoxifen use, renal impairment, lower body weight, and potentially the presence of macular disease. Risk is most accurately assessed on the basis of duration of use relative to daily dose/body weight (Marmor [AAO 2016]; Melles 2014). Based on these risks, the American Academy of Ophthalmology (AAO) recommends not exceeding a daily chloroquine phosphate dosage of 2.3 mg/kg using actual body weight. Previous recommendations to use ideal body weight are no longer advised; very thin patients in particular were at increased risk for retinal toxicity using this practice. Current AAO guidelines do not specifically address dosing in obese patients. AAO also recommends baseline screening for retinal toxicity and annual screening beginning after 5 years of use (or sooner if major risk factors are present) (Marmor [AAO 2016]).
Disease-related concerns:
• Auditory damage: Use with caution in patients with preexisting auditory damage; discontinue immediately if hearing defects are noted.
• G6PD deficiency: Although the manufacturer’s labeling recommends chloroquine be used with caution in patients with G6PD deficiency due to a potential for hemolytic anemia, there is limited data to support this risk. Many experts consider chloroquine, when given in usual therapeutic doses to WHO Class II and III G6PD deficient patients, to probably be safe (Cappellini 2008; Luzzatto 2016; Youngster 2010). In a trial conducted in West Africa involving 74 G6PD deficient patients (predominantly Class III deficiency), there were no cases of hemolysis reported following exposure to usual doses of chloroquine (Mandi 2005). In addition, the ACR Rheumatology guidelines do not mention the need to evaluate G6PD levels prior to initiation of therapy (Singh 2015).
• Hepatic impairment: Use with caution in patients with hepatic impairment, alcoholism, or concurrent therapy with hepatotoxic agents.
• Myasthenia gravis: Use may worsen or precipitate new myasthenia gravis (MG); use only if necessary and monitor for worsening MG (AAN [Narayanaswami 2021]).
• Porphyria: Use with caution in patients with porphyria; may exacerbate disease symptoms.
• Psoriasis: Use with caution in patients with psoriasis; may exacerbate disease symptoms.
• Seizure disorder: Use with caution in patients with a history of seizure disorder; may cause seizures.
Other warnings/precautions:
• Appropriate use: Chloroquine does not prevent relapses in patients with vivax or ovale malaria (not effective against exoerythrocytic forms); additional treatment with an antimalarial effective against these forms (eg, an 8-aminoquinoline) is required for the treatment of infections with P. vivax and P. ovale. Do not use for the treatment of complicated malaria (high-grade parasitemia and/or complications [eg, cerebral malaria, acute renal failure]).
• Chloroquine resistance: Chloroquine is not effective against chloroquine- or hydroxychloroquine-resistant strains of Plasmodium species. Chloroquine resistance is widespread in P. falciparum and is reported in P. vivax. Prior to initiation of chloroquine for prophylaxis, it should be determined if chloroquine is appropriate for use in the region to be visited; do not use for malaria prophylaxis in areas where chloroquine resistance occurs. Patients should be treated with another antimalarial if patient is infected with a resistant strain of plasmodia.
Excipient information presented when available (limited, particularly for generics); consult specific product labeling.
Tablet, Oral, as phosphate:
Generic: 250 mg [equivalent to chloroquine base 150 mg], 500 mg [equivalent to chloroquine base 300 mg]
Yes
Tablets (Chloroquine Phosphate Oral)
250 mg (per each): $9.19
500 mg (per each): $22.77 - $23.85
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. [DSC] = Discontinued product
Tablet, Oral, as phosphate:
Generic: 250 mg [equivalent to chloroquine base 150 mg] [DSC]
16.67 mg chloroquine PHOSPHATE/mL (equivalent to 10 mg chloroquine BASE/mL) Oral Suspension (ASHP Standard Concentration) (ASHP 2017)
A 16.67 mg chloroquine PHOSPHATE/mL oral suspension (equivalent to 10 mg chloroquine BASE/mL) may be made from tablets. Crush two 500 mg chloroquine PHOSPHATE tablets (equivalent to 300 mg BASE/tablet) in a mortar and reduce to a fine powder. Add a small amount of sterile water for irrigation, USP and mix to a uniform paste; mix while adding cherry syrup in incremental proportions to almost 60 mL; transfer to a calibrated amber glass bottle, rinse mortar with cherry syrup, and add sufficient quantity of cherry syrup to make 60 mL. Label "shake well". Stable for 4 weeks when stored at room temperature or refrigerated (Mirochnick 1994).
15 mg chloroquine PHOSPHATE/mL (equivalent to 9 mg chloroquine BASE/mL) Oral Suspension
A 15 mg chloroquine PHOSPHATE/mL oral suspension (equivalent to 9 mg chloroquine BASE/mL) may be made from tablets and a 1:1 mixture of Ora-Sweet and Ora-Plus. Crush three 500 mg chloroquine PHOSPHATE tablets (equivalent to 300 mg BASE/tablet) in a mortar and reduce to a fine powder. Add 15 mL of the vehicle and mix to a uniform paste; mix while adding the vehicle in incremental proportions to almost 100 mL; transfer to a calibrated bottle, rinse mortar with vehicle, and add quantity of vehicle sufficient to make 100 mL. Label "shake well before using" and "protect from light". Stable for up to 60 days when stored in the dark at room temperature or refrigerated (preferred).
A 15 mg chloroquine PHOSPHATE/mL oral suspension (equivalent to 9 mg chloroquine BASE/mL) may be made using chloroquine phosphate pharmaceutical grade powder and SyrSpend SF PH4. Weigh 1,500 mg of chloroquine phosphate powder, add to mortar and triturate to a fine powder. Add a small amount of vehicle and mix to a uniform base, mix while adding the vehicle in incremental proportions to almost 100 mL; transfer to calibrated bottle, rinse mortar with vehicle, and add quantity of vehicle sufficient to make 100 mL. Label "shake well". Stable for up to 90 days when stored at room temperature or refrigerated.
Oral: Administer with meals to decrease GI adverse effects (Ref); chloroquine phosphate tablets have also been mixed with chocolate syrup or enclosed in gelatin capsules to mask the bitter taste (Ref).
Oral: Administer with food to decrease GI adverse effects (Ref).
Store at 25°C (77°F); excursions are permitted between 15°C and 30°C (59°F and 86°F); protect from light.
Treatment of uncomplicated malaria due to susceptible species (FDA approved in pediatric patients [age not specified] and adults); prophylaxis of malaria in geographic areas where chloroquine resistance is not present (FDA approved in pediatric patients [age not specified] and adults); treatment of extraintestinal amebiasis (FDA approved in adults).
Note: Chloroquine alone does not prevent relapses in patients with P. vivax or P. ovale malaria.
Aralen [US, Mexico] may be confused with Paralen brand name for acetaminophen [Czech Republic]
Substrate of CYP2C8 (Minor), CYP2D6 (Minor), CYP3A4 (Minor), MATE1/2-K; Note: Assignment of Major/Minor substrate status based on clinically relevant drug interaction potential; Inhibits CYP2D6 (Weak);
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.
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
Agalsidase Alfa: Chloroquine may decrease therapeutic effects of Agalsidase Alfa. Risk X: Avoid
Agalsidase Beta: Chloroquine may decrease therapeutic effects of Agalsidase Beta. Management: Avoid concomitant use of chloroquine with agalsidase beta when possible as chloroquine could antagonize intracellular alpha-galactosidase activity. Risk D: Consider Therapy Modification
Amisulpride (Oral): May increase QTc-prolonging effects of QT-prolonging Agents (Moderate Risk). Risk C: Monitor
Ampicillin: Chloroquine may decrease serum concentration of Ampicillin. Management: Separate the administration of ampicillin and chloroquine by at least 2 hours to minimize any potential negative impact of chloroquine on ampicillin bioavailability. Risk D: Consider Therapy Modification
Androgens: May increase hypoglycemic effects of Agents with Blood Glucose Lowering Effects. Risk C: Monitor
Antacids: May decrease serum concentration of Chloroquine. Management: Separate the administration of antacids and chloroquine by at least 4 hours to minimize any potential negative impact of antacids on chloroquine bioavailability. Risk D: Consider Therapy Modification
Antidiabetic Agents: May increase hypoglycemic effects of Hypoglycemia-Associated Agents. Risk C: Monitor
Artemether and Lumefantrine: Antimalarial Agents may increase adverse/toxic effects of Artemether and Lumefantrine. Management: Artemether/lumefantrine (combination product) should not be used with other antimalarials unless there is no other treatment option. If combined, monitor patients for increased toxicities of both agents, including QTc interval prolongation. Risk D: Consider Therapy Modification
Bacampicillin: Chloroquine may decrease serum concentration of Bacampicillin. Management: Separate the administration of ampicillin and chloroquine by at least 2 hours to minimize any potential negative impact of chloroquine on ampicillin bioavailability. Bacampicillin is a prodrug of ampicillin. Risk D: Consider Therapy Modification
Charcoal, Activated: May decrease serum concentration of Chloroquine. Risk C: Monitor
Chlorprothixene: May increase QTc-prolonging effects of Antimalarial Agents. Risk X: Avoid
Cholera Vaccine: Chloroquine may decrease therapeutic effects of Cholera Vaccine. Management: Administer cholera vaccine at least 10 days prior to initiation of chloroquine. Risk D: Consider Therapy Modification
Cimetidine: May increase serum concentration of Chloroquine. Risk X: Avoid
Ciprofloxacin (Systemic): Chloroquine may increase hyperglycemic effects of Ciprofloxacin (Systemic). Chloroquine may increase hypoglycemic effects of Ciprofloxacin (Systemic). Chloroquine may increase QTc-prolonging effects of Ciprofloxacin (Systemic). Risk C: Monitor
CycloSPORINE (Systemic): Chloroquine may increase serum concentration of CycloSPORINE (Systemic). Risk C: Monitor
Dabrafenib: QT-prolonging Miscellaneous Agents (Moderate Risk) may increase QTc-prolonging effects of Dabrafenib. Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk C: Monitor
Dapsone (Systemic): Antimalarial Agents may increase adverse/toxic effects of Dapsone (Systemic). Specifically, concomitant use of antimalarial agents with dapsone may increase the risk of hemolytic reactions. Dapsone (Systemic) may increase adverse/toxic effects of Antimalarial Agents. Specifically, concomitant use of dapsone with antimalarial agents may increase the risk for hemolytic reactions. Management: Closely monitor patients for signs/symptoms of hemolytic reactions with concomitant use of dapsone and antimalarial agents, particularly in patients deficient in glucose-6-phosphate dehydrogenase (G6PD), methemoglobin reductase, or with hemoglobin M. Risk D: Consider Therapy Modification
Dapsone (Topical): Antimalarial Agents may increase adverse/toxic effects of Dapsone (Topical). Specifically, the risk of hemolytic reactions may be increased. Management: Consider avoidance of this combination when possible. If combined, closely monitor for signs/symptoms of hemolytic reactions. Patients with glucose-6-phosphate dehydrogenase deficiency may be at particularly high risk for adverse hematologic effects. Risk D: Consider Therapy Modification
Domperidone: QT-prolonging Agents (Moderate Risk) may increase QTc-prolonging effects of Domperidone. Risk X: Avoid
Encorafenib: May increase QTc-prolonging effects of QT-prolonging Miscellaneous Agents (Moderate Risk). Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk C: Monitor
Fluorouracil Products: QT-prolonging Miscellaneous Agents (Moderate Risk) may increase QTc-prolonging effects of Fluorouracil Products. Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk C: Monitor
Haloperidol: QT-prolonging Miscellaneous Agents (Moderate Risk) may increase QTc-prolonging effects of Haloperidol. Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk C: Monitor
Herbal Products with Glucose Lowering Effects: May increase hypoglycemic effects of Hypoglycemia-Associated Agents. Risk C: Monitor
Hibiscus: May decrease serum concentration of Chloroquine. Risk C: Monitor
Hypoglycemia-Associated Agents: May increase hypoglycemic effects of Hypoglycemia-Associated Agents. Risk C: Monitor
Kaolin: May decrease serum concentration of Chloroquine. Management: Separate the administration of kaolin and chloroquine by at least 4 hours to minimize any potential negative impact of kaolin on chloroquine bioavailability. Risk D: Consider Therapy Modification
Lanthanum: May decrease serum concentration of Chloroquine. Management: Administer chloroquine at least two hours before or after lanthanum. Risk D: Consider Therapy Modification
Lemon: May decrease serum concentration of Chloroquine. Risk C: Monitor
Levoketoconazole: QT-prolonging Agents (Moderate Risk) may increase QTc-prolonging effects of Levoketoconazole. Risk X: Avoid
Local Anesthetics: Methemoglobinemia Associated Agents may increase adverse/toxic effects of Local Anesthetics. Specifically, the risk for methemoglobinemia may be increased. Risk C: Monitor
Maitake: May increase hypoglycemic effects of Agents with Blood Glucose Lowering Effects. Risk C: Monitor
Mefloquine: Aminoquinolines (Antimalarial) may increase adverse/toxic effects of Mefloquine. Specifically, the risk for QTc-prolongation and the risk for convulsions may be increased. Management: Avoid concurrent use, and delay administration of mefloquine until at least 12 hours after the last dose of an aminoquinoline antimalarial. Risk X: Avoid
Mivacurium: Chloroquine may increase therapeutic effects of Mivacurium. Risk C: Monitor
Monoamine Oxidase Inhibitors: May increase hypoglycemic effects of Agents with Blood Glucose Lowering Effects. Risk C: Monitor
Nitric Oxide: May increase adverse/toxic effects of Methemoglobinemia Associated Agents. Combinations of these agents may increase the likelihood of significant methemoglobinemia. Risk C: Monitor
Ondansetron: QT-prolonging Miscellaneous Agents (Moderate Risk) may increase QTc-prolonging effects of Ondansetron. Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk C: Monitor
Pegvisomant: May increase hypoglycemic effects of Agents with Blood Glucose Lowering Effects. Risk C: Monitor
Pentamidine (Systemic): QT-prolonging Miscellaneous Agents (Moderate Risk) may increase QTc-prolonging effects of Pentamidine (Systemic). Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk C: Monitor
Pimozide: May increase QTc-prolonging effects of QT-prolonging Agents (Moderate Risk). Risk X: Avoid
Piperaquine: QT-prolonging Agents (Moderate Risk) may increase QTc-prolonging effects of Piperaquine. Risk X: Avoid
Praziquantel: Chloroquine may decrease serum concentration of Praziquantel. Risk C: Monitor
Prilocaine: Methemoglobinemia Associated Agents may increase adverse/toxic effects of Prilocaine. Combinations of these agents may increase the likelihood of significant methemoglobinemia. Management: Monitor for signs of methemoglobinemia when prilocaine is used in combination with other agents associated with development of methemoglobinemia. Avoid use of these agents with prilocaine/lidocaine cream in infants less than 12 months of age. Risk C: Monitor
Primaquine: Chloroquine may increase serum concentration of Primaquine. Risk C: Monitor
Prothionamide: May increase hypoglycemic effects of Agents with Blood Glucose Lowering Effects. Risk C: Monitor
QT-prolonging Agents (Highest Risk): May increase QTc-prolonging effects of Chloroquine. Management: Consider alternatives to this combination. If combined, monitor for QTc interval prolongation and ventricular arrhythmias. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk D: Consider Therapy Modification
QT-prolonging Antidepressants (Moderate Risk): May increase QTc-prolonging effects of QT-prolonging Miscellaneous Agents (Moderate Risk). Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk C: Monitor
QT-prolonging Antipsychotics (Moderate Risk): QT-prolonging Miscellaneous Agents (Moderate Risk) may increase QTc-prolonging effects of QT-prolonging Antipsychotics (Moderate Risk). Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk C: Monitor
QT-prolonging Class IC Antiarrhythmics (Moderate Risk): QT-prolonging Miscellaneous Agents (Moderate Risk) may increase QTc-prolonging effects of QT-prolonging Class IC Antiarrhythmics (Moderate Risk). Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk C: Monitor
QT-Prolonging Inhalational Anesthetics (Moderate Risk): QT-prolonging Miscellaneous Agents (Moderate Risk) may increase QTc-prolonging effects of QT-Prolonging Inhalational Anesthetics (Moderate Risk). Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk C: Monitor
QT-prolonging Kinase Inhibitors (Moderate Risk): May increase QTc-prolonging effects of QT-prolonging Miscellaneous Agents (Moderate Risk). Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk C: Monitor
QT-prolonging Miscellaneous Agents (Moderate Risk): May increase QTc-prolonging effects of Chloroquine. Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk C: Monitor
QT-prolonging Moderate CYP3A4 Inhibitors (Moderate Risk): May increase QTc-prolonging effects of QT-prolonging Miscellaneous Agents (Moderate Risk). QT-prolonging Moderate CYP3A4 Inhibitors (Moderate Risk) may increase serum concentration of QT-prolonging Miscellaneous Agents (Moderate Risk). Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk C: Monitor
QT-prolonging Quinolone Antibiotics (Moderate Risk): QT-prolonging Miscellaneous Agents (Moderate Risk) may increase QTc-prolonging effects of QT-prolonging Quinolone Antibiotics (Moderate Risk). Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk C: Monitor
QT-prolonging Strong CYP3A4 Inhibitors (Moderate Risk): May increase QTc-prolonging effects of QT-prolonging Miscellaneous Agents (Moderate Risk). Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk C: Monitor
Quinolones: May increase hypoglycemic effects of Agents with Blood Glucose Lowering Effects. Quinolones may decrease therapeutic effects of Agents with Blood Glucose Lowering Effects. Specifically, if an agent is being used to treat diabetes, loss of blood sugar control may occur with quinolone use. Risk C: Monitor
Rabies Vaccine: Aminoquinolines (Antimalarial) may decrease therapeutic effects of Rabies Vaccine. Management: If coadministration is unavoidable during rabies post-exposure vaccination, give a 5th dose of the rabies vaccine. If coadministration is unavoidable during rabies pre-exposure vaccination, ensure antibody titers are greater than or equal to 0.5 IU/mL. Risk D: Consider Therapy Modification
Remdesivir: Chloroquine may decrease therapeutic effects of Remdesivir. Risk X: Avoid
Salicylates: May increase hypoglycemic effects of Agents with Blood Glucose Lowering Effects. Risk C: Monitor
Selective Serotonin Reuptake Inhibitor: May increase hypoglycemic effects of Agents with Blood Glucose Lowering Effects. Risk C: Monitor
Sertindole: May increase QTc-prolonging effects of QT-prolonging Agents (Moderate Risk). Risk X: Avoid
Sodium Nitrite: Methemoglobinemia Associated Agents may increase adverse/toxic effects of Sodium Nitrite. Combinations of these agents may increase the likelihood of significant methemoglobinemia. Risk C: Monitor
Succinylcholine: Chloroquine may increase neuromuscular-blocking effects of Succinylcholine. Risk C: Monitor
Tamoxifen: May increase adverse/toxic effects of Chloroquine. Specifically, concomitant use of tamoxifen and chloroquine may increase the risk of retinal toxicity. Risk C: Monitor
Thioridazine: May increase QTc-prolonging effects of Chloroquine. Chloroquine may increase serum concentration of Thioridazine. Risk X: Avoid
Patients who are likely to become pregnant are advised to avoid travel to malaria-risk areas. When travel is unavoidable, precautions should be taken to avoid mosquito bites and effective prophylactic medications should be used. Medications considered acceptable for the prophylaxis of malaria during pregnancy may be used in patients trying to conceive. Chloroquine is considered acceptable for use in pregnant patients (CDC 2023; CDC Yellow Book 2024).
Chloroquine and its metabolites cross the placenta and can be detected in the cord blood and urine of the newborn infant (Akintonwa 1988; Essien 1982; Law 2008). In one study, chloroquine and its metabolites were measurable in the cord blood 89 days (mean) after the last maternal dose (Law 2008).
Chloroquine has not been found to increase the risk of adverse fetal events when used in recommended doses for malaria prophylaxis (CDC Yellow Book 2024). Retinal toxicity is a known risk following long-term use or high doses of chloroquine. Although animal reproduction studies have shown accumulation of chloroquine in fetal ocular tissues, an association between chloroquine and fetal ocular toxicity has not been confirmed in available human studies (Gaffar 2019; Osadchy 2011).
Due to pregnancy-induced physiologic changes, some pharmacokinetic properties of chloroquine may be altered (Chukwuani 2004; Fakeye 2002; Karunajeewa 2010; Lee 2008; Massele 1997; Olafuyi 2019; Salman 2017; Wilby 2011). Available studies suggest dose adjustments could be needed, but data are not sufficient to determine what an appropriate dosing change is when chloroquine is used for the treatment or prophylaxis of malaria during pregnancy (Karunajeewa 2010; Salman 2017).
Malaria infection during pregnancy may be more severe than in nonpregnant people and has a high risk of maternal and perinatal morbidity and mortality. Malaria infection during pregnancy can lead to miscarriage, premature delivery, low birth weight, congenital infection, and/or perinatal death. Therefore, pregnant patients are advised to avoid travel to malaria-risk areas. When travel is unavoidable, pregnant patients should take precautions to avoid mosquito bites and use effective prophylactic medications (CDC 2023; CDC Yellow Book 2024).
Indications and dosing of chloroquine for prophylaxis and treatment of uncomplicated malaria are the same in pregnant and nonpregnant adults. Chloroquine may be used in all trimesters of pregnancy (CDC 2023; CDC Yellow Book 2024). Consult current CDC malaria guidelines.
Note: Determinants for laboratory testing (ie, specific tests to monitor and frequency) should take into consideration patient's clinical status and duration of therapy (short-term versus long-term). Laboratory monitoring may be unnecessary in patients receiving short-term therapy.
CBC and platelet count with differential, liver function, and renal function at baseline and periodically during therapy; blood glucose (if symptoms of hypoglycemia occur); muscle strength (especially proximal) during prolonged therapy; monitor ECG at baseline and as clinically indicated in patients at elevated risk of QTc prolongation.
Ophthalmologic exam within the first year of prolonged or high-dose treatment (fundus examination plus visual fields and spectral-domain optical coherence tomography if maculopathy is present) to screen for retinal toxicity, followed by annual screening beginning after 3 to 5 years of use (or sooner if major risk factors are present) (AAO [Marmor 2016]; WHO 2012).
Antimalarial: Binds to and inhibits DNA and RNA polymerase; interferes with metabolism and hemoglobin utilization by parasites; inhibits prostaglandin effects; chloroquine concentrates within parasite acid vesicles and raises internal pH resulting in inhibition of parasite growth; may involve aggregates of ferriprotoporphyrin IX acting as chloroquine receptors causing membrane damage; may also interfere with nucleoprotein synthesis.
Absorption: Rapid and almost complete.
Distribution: Widely in body tissues including eyes, heart, kidneys, liver, leukocytes, and lungs where retention is prolonged.
Protein binding: ~55%.
Metabolism: Partially hepatic to main metabolite, desethylchloroquine.
Half-life (Salako 1984):
Healthy subjects: 74.7 ± 30.1 hours.
Chronic renal insufficiency: 191.4 ± 69.1 hours (range: 103.5 to 309.9 hours).
Time to peak serum concentration: Oral: Within 1 to 2 hours.
Excretion: Urine (~70%; ~35% as unchanged drug); acidification of urine increases elimination; small amounts of drug may be present in urine months following discontinuation of therapy.
Kidney impairment: Half-life is prolonged with chronic kidney impairment and there is reduced conversion to desethylchloroquine (Krishna 1996; Salako 1984).
