Version May 2024
Dosage guidance:
Safety: For patients with respiratory disease, initiate therapy at the lowest dose (Ref).
Alcohol use disorder, moderate to severe (alternative agent) (off-label use):
Note: Gabapentin is suggested by some experts as an alternative when first-line agents cannot be used (Ref). Gabapentin may be misused by some patients with substance use disorders; evaluate for risk and signs of addiction and dependence (Ref).
Immediate release: Oral: Initial: 300 mg once daily; increase dose based on response and tolerability in increments of 300 mg every 1 to 2 days up to a target dose of 600 mg 3 times daily (Ref). Some experts consider alternative therapy if goals are not met within 6 months of treatment (Ref).
Alcohol withdrawal (off-label use):
Note: Withdrawal will progress at different rates in some patients; flexibility in dosing and duration is warranted (Ref). Regimens vary and depend on withdrawal history, degree of current withdrawal symptoms, quantity of alcohol consumption, concomitant medications for breakthrough symptoms, and whether the patient is treated inpatient or in the ambulatory setting. For example, in an inpatient study that enrolled patients with Clinical Institute Withdrawal Assessment (CIWA) scores >15 and offered no as-needed medications for breakthrough withdrawal symptoms, 3.2 g in divided doses was offered on day 1 of treatment (Ref). Many facilities only treat alcohol withdrawal in the ambulatory setting if CIWA score is ≤15 and there is no history of withdrawal seizures or delirium tremens (Ref). The following are two suggested regimens.
CIWA score <10: Immediate release: Oral: Initial: 300 mg every 6 hours on day 1, then 300 mg every 8 hours on day 2, then 300 mg every 12 hours on day 3, then 300 mg at night on day 4. In addition to scheduled doses, provide one additional as-needed 300 mg dose per day for breakthrough withdrawal symptoms (Ref).
CIWA score 10 to 18 (alternative agent) (Ref): Immediate release: Oral: Initial: 300 to 400 mg 3 times daily on days 1 through 3, then 300 to 400 mg twice daily on day 4, then discontinue. For breakthrough symptoms during days 1 through 4, consider providing single doses of 100 mg, which may be administered up to 3 times daily, and a 300 mg dose reserved for the evening (Ref).
Cough, chronic refractory (alternative agent) (off-label use):
Note: Reserve for patients with cough lasting >8 weeks who have had negative responses to treatments for asthma, gastroesophageal reflux disease, and rhinitis (Ref).
Immediate release: Oral: Initial: 300 mg once daily (Ref); if significant somnolence develops, some experts recommend decreasing dose to 100 mg once daily (Ref). May increase dose gradually based on response and tolerability in increments of 300 mg to a maximum dose of 900 mg twice daily (Ref). Re-evaluate therapeutic need after 6 months (Ref).
Fibromyalgia (alternative agent) (off-label use):
Note: For patients who do not respond to or tolerate preferred agents (Ref):
Immediate release: Oral: Initial: 100 to 300 mg once daily at bedtime; increase dose gradually based on response and tolerability every 1 to 2 weeks to a target dose of 1.2 to 2.4 g/day in divided doses (Ref).
Generalized anxiety disorder (alternative agent) (off-label use):
Note: Adjunctive therapy for short-term symptom relief until concurrent therapy is effective (eg, 4 to 6 weeks, followed by tapering). Long-term augmentation may be considered when preferred treatments (eg, serotonin reuptake inhibitors) are partially effective (Ref).
Immediate release: Oral: Initial: 300 mg/day; may increase dose every ≥3 days based on response and tolerability up to 2.4 g/day, in 2 to 3 divided doses (Ref). Note: In patients sensitive to side effects, some experts suggest a lower starting dose of 100 mg/day and more gradual titration (Ref).
Hiccups (singultus) (off-label use ): Immediate release: Oral: Usual dose range: 300 mg to 1.2 g/day in 3 to 4 divided doses (Ref). Can be discontinued the day after hiccups subside; long-term therapy may be warranted for persistent or relapsing hiccups (eg, palliative care) (Ref). Note: In patients with refractory hiccups, may use in combination with a proton pump inhibitor, baclofen, or metoclopramide (Ref).
Neuropathic pain:
General dosing recommendations (for other than postherpetic neuralgia) (off-label use):
Note: For chronic use, an adequate trial with gabapentin may require 2 months or more (Ref). For critically ill patients with neuropathic pain, gabapentin may be a useful component of multimodal pain control (Ref).
Immediate release: Oral: Initial: 100 to 300 mg 1 to 3 times daily (Ref); increase dose based on response and tolerability to a target dose range of 300 mg to 1.2 g 3 times daily (Ref).
Extended release: Oral: Initial: 300 mg at bedtime; increase dose based on response and tolerability to a target dose of 900 mg to 3.6 g once daily (Ref).
Postherpetic neuralgia:
Immediate release: Oral: 300 mg once on day one, 300 mg twice daily on day 2, and 300 mg 3 times daily on day 3, then increase as needed up to 1.8 to 3.6 g/day in divided doses. Additional benefit of doses >1.8 g/day has not been established.
Extended release: Oral: Initial: 300 mg once daily; increase by 300 mg each day up to 900 mg once daily. Further increase as needed up to 1.8 g once daily. Additional benefit of doses >1.8 g/day has not been established.
Pruritus, chronic (alternative agent) (off-label use):
Note: For patients with pruritus resistant to preferred therapies (Ref):
Neuropathic (eg, brachioradial pruritus, notalgia paresthetica) or malignancy-related pruritus: Immediate release: Oral: Initial: 300 mg/day in 1 to 3 divided doses; increase dose based on response and tolerability up to 1.8 g/day in divided doses (Ref). Higher doses up to 3.6 g/day have been used in oncology populations (Ref).
Uremic pruritus: Immediate release: Oral: Initial: 100 mg after dialysis on hemodialysis days; may increase dose based on response and tolerability up to 300 mg after dialysis on hemodialysis days (Ref).
Restless legs syndrome (off-label use): Immediate release: Oral: Initial: 100 to 300 mg once daily 2 hours before bedtime; may increase dose every 1 to 2 weeks until symptom relief is achieved (range: 300 mg to 2.4 g/day). Suggested maintenance dosing schedule for doses ≥600 mg/day: One-third of total daily dose given midday, remaining two-thirds of the total daily dose given in the evening (Ref).
Seizures, focal (partial) onset: Immediate release: Oral: Initial: 300 mg 3 times daily; increase dose based on response and tolerability. Usual dosage: 300 to 600 mg 3 times daily; doses up to 2.4 g/day and 3.6 g/day have been tolerated in long-term and short-term clinical studies, respectively. Some experts recommend a lower starting dose (eg, 100 mg 3 times daily) with titration as tolerated (Ref).
Social anxiety disorder (alternative agent) (off-label use):
Note: Monotherapy or adjunctive therapy for patients who do not tolerate or respond to preferred agents (Ref):
Immediate release: Oral: Initial: 300 mg twice daily; increase dose based on response and tolerability in increments of no more than 300 mg/day up to a maximum of 3.6 g/day in 3 divided doses (Ref). Some experts recommend initiating with 100 mg 3 times daily in patients with respiratory disease (Ref).
Vasomotor symptoms associated with menopause (off-label use):
Immediate release: Oral: Initial: 300 to 400 mg once daily at bedtime; some experts use an initial dose of 100 mg once daily to avoid adverse effects (Ref); increase gradually (eg, over 3 to 12 days) based on response and tolerability up to 600 mg to 2.4 g/day in 2 to 3 divided doses (Ref). Some experts suggest gabapentin for women whose symptoms occur primarily at night and favor a maximum dose of 900 mg to 1.2 g, given as one dose at bedtime (Ref).
Extended release: Oral: Initial: 600 mg once daily at bedtime; increase gradually (eg, 600 mg every 3 days) to target dose of 600 mg in the morning and 1.2 g at bedtime (Ref).
Discontinuation of therapy: In patients receiving gabapentin chronically, unless safety concerns require a more rapid withdrawal, gabapentin should be withdrawn gradually over ≥1 week to minimize the potential of increased seizure frequency (in patients with epilepsy) or other withdrawal symptoms (eg, confusion, irritability, tachycardia, diaphoresis) (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 Roberts, PhD, BPharm (Hons), B App Sc, FSHP, FISAC; Michael Heung, MD, MS.
Oral: Immediate release:
Note: Initial doses of gabapentin should be conservative and titrated based on effectiveness and tolerability.
|
CrCl (mL/minute)c |
Approximate Maintenance Dose Adjustment |
Maximum Maintenance Dose |
|---|---|---|
|
aChoose normal dose based on indication (see Adult dosing), then choose the adjusted dose from the column corresponding to the patient's CrCl. | ||
|
bExpert opinion derived from Blum 1994, Davison 2014, Davison 2019, manufacturer's labeling. | ||
|
cEstimation of renal function for dosing adjustments should be done using the Cockcroft Gault formula. | ||
|
>79 |
No dose adjustment necessary |
3,600 mg/day in 3 divided doses |
|
50 to 79 |
No dose adjustment necessary, not to exceed 1,800 mg/day |
1,800 mg/day in 3 divided doses |
|
30 to 49 |
~50% reduction |
900 mg/day in 2 to 3 divided doses |
|
15 to 29 |
~75% reduction |
600 mg/day in 1 to 2 divided doses |
|
<15 |
~90% reduction |
300 mg/day in 1 dose |
Hemodialysis, intermittent (thrice weekly): Dialyzable (50% over 4 hours (Ref)):
Initial: 100 mg 3 times per week after hemodialysis. Titrate to effect up to 300 mg 3 times per week given after hemodialysis on dialysis days (Ref).
Note: Some experts recommend cautious titration to a maximum of 300 mg/day in select patients requiring additional pain control (Ref).
Peritoneal dialysis:
Initial: 100 mg every other day. Titrate to effect up to 300 mg every other day (Ref).
Note: Some experts recommend cautious titration to a maximum of 300 mg/day in select patients requiring additional pain control (Ref).
CRRT:
Note: Drug clearance is dependent on the effluent flow rate, filter type, and method of renal replacement. Recommendations are based on high-flux dialyzers and effluent flow rates of 20 to 25 mL/kg/hour (or approximately 1,500 to 3,000 mL/hour) unless otherwise noted.
CVVH/CVVHD/CVVHDF:
Note: Dosing based on expert opinion; no evidence available. Pharmacokinetic characteristics and one case report suggest gabapentin is cleared by CRRT (Ref).
Initial: 100 mg twice daily and titrate to effect. Suggested maximum dose: 300 mg twice daily.
Oral: Extended release:
Note: Follow initial dose titration schedule if treatment naive. Estimation of renal function for dosing adjustments should be done using the Cockcroft-Gault formula. Renally adjusted dose recommendations are based on doses up to 1.8 g/day.
CrCl ≥60 mL/minute: Oral: No dosage adjustment necessary.
CrCl >30 to 59 mL/minute: Oral: 600 mg to 1.8 g once daily; dependent on tolerability and clinical response.
CrCl <30 mL/minute: Use is not recommended.
End-stage renal disease requiring hemodialysis: Use is not recommended.
Peritoneal dialysis: Use is not recommended.
The hepatic dosing recommendations are based upon the best available evidence and clinical expertise. Senior Editorial Team: Matt Harris, PharmD, MHS, BCPS, FAST; Jeong Park, PharmD, MS, BCTXP, FCCP, FAST; Arun Jesudian, MD; Sasan Sakiani, MD.
Note: Initial doses of gabapentin should be conservative and titrated based on effectiveness and tolerability. The following recommendations are based on the use of IR formulations of gabapentin only; there are insufficient data to make dosage recommendations for the ER formulations in patients with hepatic impairment.
Initial or dose titration in patients with preexisting liver cirrhosis : Note: Use with caution in patients with hepatic encephalopathy, renal impairment, or concomitant use of other CNS depressants (Ref).
Child-Turcotte-Pugh class A: Oral: No dosage adjustment necessary (Ref).
Child-Turcotte-Pugh class B and C: Oral: Initial: ≤300 mg per day in 1 to 3 divided doses; may titrate as tolerated to the usual indication-specific maximum recommended dose (Ref).
Dosage adjustment in patients with chronic, worsening hepatic function during treatment (eg, progression from Child-Turcotte-Pugh class A to B): Note: Use with caution in patients with hepatic encephalopathy, renal impairment, or concomitant use of CNS depressants (Ref).
New Child-Turcotte-Pugh class A: Oral: No dosage adjustment necessary (Ref).
Progression to Child-Turcotte-Pugh class B and C: Oral: No dosage adjustment necessary (Ref).
Acute worsening of hepatic function (eg, requiring hospitalization):Consider an initial 50% reduction in daily dose to mitigate signs and symptoms associated with hepatic encephalopathy; especially if patient presents with concurrent renal insufficiency (Ref). If discontinuation of gabapentin is necessary, a more rapid taper (eg, 50% reduction in daily dose every 3 to 4 days) while hospitalized with frequent monitoring for withdrawal is recommended (Ref).
Restless legs syndrome (off-label use): Immediate release: Oral: Initial: 100 mg once daily (Ref).
Other indications: Initiate therapy at the lowest dose (Ref). Refer to adult dosing.
Discontinuation of therapy: Refer to adult dosing.
(For additional information see "Gabapentin: Pediatric drug information")
Dosage guidance:
Dosing: Pediatric doses presented as mg/kg/day and mg/kg/dose; use precaution.
Seizures, partial onset; adjunctive therapy: Note: Do not exceed 12 hours between doses with 3-times-daily dosing. If gabapentin is discontinued or if another antiseizure medication is added to therapy, it should be done slowly over a minimum of 1 week.
Children 3 to <12 years: Immediate release:
Initial: Oral: 10 to 15 mg/kg/day divided into 3 doses daily; titrate dose upward over ~3 days.
Maintenance usual dose:
Children 3 to 4 years: Oral: 40 mg/kg/day divided into 3 doses daily; maximum daily dose: In one long-term study, doses up to 50 mg/kg/day were well-tolerated.
Children 5 to <12 years: Oral: 25 to 35 mg/kg/day divided into 3 doses daily; maximum daily dose: In one long-term study, doses up to 50 mg/kg/day were well-tolerated.
Children ≥12 years and Adolescents: Immediate release: Oral: Initial: 300 mg 3 times daily; titrate dose upward if needed; usual maintenance dose: 900 to 1,800 mg/day divided into 3 doses daily; doses up to 2,400 mg/day divided into 3 doses daily are well tolerated long-term; maximum daily dose: Doses up to 3,600 mg/day have been tolerated in short-term studies.
Neuropathic pain: Limited data available: Children and Adolescents: Immediate release: Oral: Initial: 5 mg/kg/dose at bedtime, maximum dose: 300 mg/dose; day 2: Increase to 5 mg/kg/dose twice daily, maximum dose: 300 mg/dose; day 3: Increase to 5 mg/kg/dose 3 times daily, maximum dose: 300 mg/dose; further titrate with dosage increases (not frequency) to effect; usual dosage range: 8 to 35 mg/kg/day divided into 3 doses daily; maximum daily dose: 3,600 mg/day; do not exceed 12 hours between doses with 3-times-daily dosing; a lower initial dose may be considered if concurrent analgesics are also sedating (Ref).
Dosage adjustment for concomitant therapy: Significant drug interactions exist, requiring dose/frequency adjustment or avoidance. Consult drug interactions database for more information.
Oral: Immediate release:
Children <12 years: There are no dosing adjustments provided in the manufacturer's labeling (has not been studied).
Children ≥12 years and Adolescents: See table.
|
CrCl |
Total Daily Dose Range |
Dosage Regimens (Maintenance Doses) | ||||
|---|---|---|---|---|---|---|
|
a CrCl <15 mL/minute: Reduce daily dose in proportion to creatinine clearance. | ||||||
|
b Supplemental dose should be administered after each 4 hours of hemodialysis (patients on hemodialysis should also receive maintenance doses based on renal function as listed in the upper portion of the table). | ||||||
|
≥60 mL/minute |
900 to 3,600 mg/day |
300 mg 3 times daily |
400 mg 3 times daily |
600 mg 3 times daily |
800 mg 3 times daily |
1,200 mg 3 times daily |
|
>30 to 59 mL/minute |
400 to 1,400 mg/day |
200 mg twice daily |
300 mg twice daily |
400 mg twice daily |
500 mg twice daily |
700 mg twice daily |
|
>15 to 29 mL/minute |
200 to 700 mg/day |
200 mg daily |
300 mg daily |
400 mg daily |
500 mg daily |
700 mg daily |
|
15 mL/minutea |
100 to 300 mg/day |
100 mg daily |
125 mg daily |
150 mg daily |
200 mg daily |
300 mg daily |
|
Hemodialysisb |
Posthemodialysis Supplemental Dose | |||||
|
125 mg |
150 mg |
200 mg |
250 mg |
350 mg | ||
There are no dosage adjustments provided in the manufacturer's labeling; however, adjustment not necessary since gabapentin is not hepatically metabolized.
Gabapentin may cause dose-dependent CNS depression and present as dizziness and/or drowsiness. In addition, serious, life-threatening, and fatal respiratory depression may occur; most cases occur with concomitant use of CNS depressants (especially opioids) in the setting of underlying respiratory impairment or in older patients (Ref). CNS depression may impair physical or mental abilities and result in accidental injury, including falls.
Mechanism: Dose-related; related to pharmacologic action (ie, structurally related to GABA)
Onset: Varied; timing impacted by concomitant use of medications known to cause CNS depression (eg, opioids) (Ref)
Risk factors:
• Concomitant use of alcohol or other CNS depressants (eg, opioids, benzodiazepines, antidepressants, antihistamines) (Ref)
• Patients with underlying respiratory impairment (Ref)
• Older patients (Ref)
Anaphylaxis or angioedema may occur. Signs and symptoms may include dyspnea, swelling of the lips, throat, and tongue, and hypotension (manufacturer’s labeling).
Mechanism: Non-dose-related; immunologic. In general, anaphylaxis is an IgE-mediated reaction (Ref).
Onset: Rapid; most anaphylactic reactions occur within minutes to hours of administration (Ref).
Risk factors:
• Prior history of immediate hypersensitivity reaction to gabapentin. Note: It is unknown whether cross-reactivity exists between gabapentin and pregabalin, given their similar structures. If an agent with similar structure is prescribed in a patient with a documented allergy to this drug, the possibility of cross-reactivity should be considered.
Isolated cases of dermatologic reactions, including maculopapular skin rash, drug reaction with eosinophilia and systemic symptoms (DRESS), Stevens-Johnson syndrome, toxic epidermal necrolysis, bullous pemphigoid, erythema multiforme, and hypersensitivity angiitis have been reported (Ref).
Mechanism: Non-dose-related; immunologic; Delayed hypersensitivity reactions are mediated by T-cells or antibodies other than IgE (eg, IgG-mediated, such as some cytopenias) (Ref). Severe cutaneous adverse reactions (SCARs) are delayed type IV hypersensitivity reactions involving a T-cell mediated drug-specific immune response (Ref).
Onset: Varied; type IV reactions are delayed hypersensitivity reactions that typically occur days to weeks after drug exposure, but may occur more rapidly (usually within 1 to 4 days) upon reexposure (Ref).
Risk factors:
• Prior history of delayed hypersensitivity reaction to gabapentin. Note: It is unknown whether cross-reactivity exists between gabapentin and pregabalin, given their similar structures. If an agent with similar structure is prescribed in a patient with a documented allergy to this drug, the possibility of cross-reactivity should be considered. Gabapentin is usually considered a safe agent for patients with a previous history of drug allergies to other antiseizure medications (Ref).
Neuropsychiatric adverse reactions have occurred in pediatric patients (ages 3 to 12 years) with epilepsy, including emotional lability; hostility (eg, aggressive behaviors); changes in behavior and thinking (eg, concentration problems, changes in school performance); and hyperkinetic muscle activity (eg, restlessness, hyperactivity). In addition, agitation has been reported following use for neuropathic pain in adult patients with cognitive impairment secondary to brain injury (Ref).
Mechanism: Non-dose-related; exact mechanism not established; one theory is gabapentin results in disinhibition similar to what is seen following benzodiazepine use (Ref).
Risk factors:
• Children with intellectual disabilities and attention-deficit/hyperactivity disorders (Ref).
Antiseizure medications (ASMs) have been associated with suicidal ideation and suicidal tendencies. However, the FDA meta-analysis has been criticized due to several important limitations (Ref). The risk of suicide is increased in epilepsy (Ref), but the occurrence of suicidal ideation/tendencies in epilepsy is multifactorial. While some ASMs (but not all) have been associated with treatment-emergent psychiatric effects such as anxiety and depression, other factors such as postictal suicidal behavior and pertinent patient history must also be evaluated to provide an accurate assessment of risk for any individual drug (Ref). In one retrospective cohort study, gabapentinoids were associated with an increased risk for suicidal behavior and pregabalin was associated with a higher risk as compared to gabapentin; however, the impact of confounding variables (eg, alcohol use, illicit drug use) could not be fully elucidated (Ref).
Mechanism: Non–dose-related. Exact mechanism not established; one theory is antiseizure medications lower the threshold for manifesting psychiatric symptoms in patients susceptible to psychiatric disorders or antiseizure-induced disinhibition and impulsiveness, thereby influencing and promoting suicidal acts (Ref).
Onset: Varied; peak incidence of suicidality across antiseizure medications (not specific to individual agents) has been noted to occur between 1 and 12 weeks of therapy (Ref). A review of clinical trials noted that risk extended from 1 week to 24 weeks of therapy, corresponding to the duration of most trials.
Risk factors:
• Preexisting risk factors for suicidal thoughts and behaviors (including epilepsy)
• Prior history of psychiatric disorders or aggressive behaviors (Ref), including history of depression (Ref)
• Use in conditions other than epilepsy (eg, chronic pain conditions) (Ref)
The following adverse drug reactions and incidences are derived from product labeling unless otherwise specified. [IR = Immediate Release, ER = Extended Release]
>10%:
Infection: Viral infection (IR, children: 11%)
Nervous system: Ataxia (IR, adolescents and adults: 1% to 13%), dizziness (IR, adolescents and adults: 17% to 28%; ER, adults: 11%; IR, children: 3%) (table 1), drowsiness (IR, adolescents and adults: 19% to 21%; IR, children: 8%; ER, adults: 5%) (table 2), fatigue (IR, adolescents and adults: 11%; IR, children: 3%)
|
Drug (Gabapentin) |
Placebo |
Population |
Dosage Form |
Indication |
Number of Patients (Gabapentin) |
Number of Patients (Placebo) |
|---|---|---|---|---|---|---|
|
3% |
2% |
Children |
IR |
Epilepsy |
119 |
128 |
|
17% |
7% |
Adolescents & adults |
IR |
Epilepsy |
543 |
378 |
|
28% |
8% |
Adults |
IR |
Postherpetic neuralgia |
336 |
227 |
|
11% |
2% |
Adults |
ER |
Postherpetic neuralgia |
359 |
364 |
|
Drug (Gabapentin) |
Placebo |
Population |
Dosage Form |
Indication |
Number of Patients (Gabapentin) |
Number of Patients (Placebo) |
|---|---|---|---|---|---|---|
|
8% |
5% |
Children |
IR |
Epilepsy |
119 |
128 |
|
19% |
9% |
Adolescents & adults |
IR |
Epilepsy |
543 |
378 |
|
21% |
5% |
Adults |
IR |
Postherpetic neuralgia |
336 |
227 |
|
5% |
3% |
Adults |
ER |
Postherpetic neuralgia |
359 |
364 |
1% to 10%:
Cardiovascular: Hypertension (ER, adults: >1%), peripheral edema (adolescents and adults: 2% to 8%), vasodilation (IR, adolescents and adults: 1%)
Dermatologic: Excoriation of skin (IR, adolescents and adults: 1%), skin rash (ER, adults: >1%)
Endocrine & metabolic: Hyperglycemia (IR, adults: 1%), weight gain (2% to 3%)
Gastrointestinal: Constipation (adolescents and adults: 1% to 4%), dental disease (IR, adolescents and adults: 2%), diarrhea (IR, adults: 6%), dyspepsia (adolescents and adults: 1% to 2%), nausea (IR: ≤8%; ER, adults: >1%), viral gastroenteritis (ER, adults: >1%), vomiting (IR: ≤8%), xerostomia (adolescents and adults: ≤5%)
Genitourinary: Erectile dysfunction (IR, adolescents and adults: 2%), urinary tract infection (ER, adults: 2%)
Infection: Herpes zoster infection (ER, adults: >1%), infection (IR, adults: 5%)
Nervous system: Abnormal gait (IR, adults: 2%), amnesia (IR, adolescents and adults: 2%), asthenia (IR, adults: 6%), changes in thinking (IR, adolescents and adults: 2% to 3%) (table 3), confusion (ER, adults: >1%), depression (IR, adolescents and adults: 2%), dysarthria (IR, adolescents and adults: 2%), emotional lability (IR, children: 4% to 6%) (table 4), hostility (IR, children: 5% to 8%) (table 5), lethargy (ER, adults: 1%), memory impairment (ER, adults: >1%), pain (ER, adults: 1%), status epilepticus (IR, adolescents and adults: 2%), tremor (IR, adolescents and adults: 7%), vertigo (ER, adults: 1%)
|
Drug (Gabapentin) |
Placebo |
Population |
Dosage Form |
Indication |
Number of Patients (Gabapentin) |
Number of Patients (Placebo) |
|---|---|---|---|---|---|---|
|
2% |
1% |
Adolescents & adults |
IR |
Epilepsy |
543 |
378 |
|
3% |
0% |
Adults |
IR |
Postherpetic neuralgia |
336 |
227 |
|
Drug (Gabapentin) |
Placebo |
Population |
Dosage Form |
Indication |
Number of Patients (Gabapentin) |
Number of Patients (Placebo) |
|---|---|---|---|---|---|---|
|
6% |
1% |
Children |
IR |
Epilepsy |
N/A |
N/A |
|
4% |
2% |
Children |
IR |
Epilepsy |
119 |
128 |
|
Drug (Gabapentin) |
Placebo |
Population |
Dosage Form |
Indication |
Number of Patients (Gabapentin) |
Number of Patients (Placebo) |
|---|---|---|---|---|---|---|
|
8% |
2% |
Children |
IR |
Epilepsy |
119 |
128 |
|
5% |
1% |
Children |
IR |
Epilepsy |
N/A |
N/A |
Neuromuscular & skeletal: Back pain (adolescents and adults: 2%), hyperkinetic muscle activity (IR, children: 3% to 5%) (table 6), joint swelling (ER, adults: >1%), limb pain (ER, adults: 2%)
|
Drug (Gabapentin) |
Placebo |
Population |
Dosage Form |
Indication |
Number of Patients (Gabapentin) |
Number of Patients (Placebo) |
|---|---|---|---|---|---|---|
|
5% |
3% |
Children |
IR |
Epilepsy |
N/A |
N/A |
|
3% |
1% |
Children |
IR |
Epilepsy |
119 |
128 |
Ophthalmic: Amblyopia (IR: 3% to 4%), conjunctivitis (IR, adults: 1%), diplopia (IR, adolescents and adults: 1% to 6%), nystagmus disorder (IR, adolescents and adults: 8%)
Otic: Otitis media (IR, adults: 1%)
Respiratory: Bronchitis (IR, children: 3%), cough (IR, adolescents and adults: 2%), dry throat (IR, adolescents and adults: ≤2%), nasopharyngitis (ER, adults: 3%), pharyngitis (IR, adolescents and adults: 1% to 3%), pneumonia (ER, adults: >1%), respiratory tract infection (IR, children: 3%), upper respiratory tract infection (ER, adults: >1%)
Miscellaneous: Accidental injury (IR, adults: 3%) (table 7), fever (IR, children: 10%; ER, adults: >1%)
|
Drug (Gabapentin) |
Placebo |
Population |
Dosage Form |
Indication |
Number of Patients (Gabapentin) |
Number of Patients (Placebo) |
|---|---|---|---|---|---|---|
|
3% |
1% |
Adults |
IR |
Postherpetic neuralgia |
336 |
227 |
Postmarketing:
Cardiovascular: Cardiomyopathy (Tellor 2019)
Dermatologic: Bullous pemphigoid (Flamm 2017), dermatitis (interstitial granulomatous) (Georgesen 2014), erythema multiforme, Stevens-Johnson syndrome (De Toledo 1999; Frey 2017; Sudana 2020), toxic epidermal necrolysis (Oskay 2006; Ragucci 2001)
Endocrine & metabolic: Altered serum glucose, amenorrhea (Berger 2004), change in libido, hypoglycemia (Penumalee 2003; Scholl 2015), hyponatremia (Falhammar 2018; Lu 2017; Wilton 2002), thyroiditis (Fyre 1999)
Genitourinary: Anorgasmia (Labbate 1999), breast hypertrophy (Zylicz 2000), ejaculation failure (Labbate 1999), ejaculatory disorder, urinary incontinence (Rissardo 2019)
Hematologic & oncologic: Thrombocytopenia (Ataki 2015)
Hepatic: Hepatotoxicity (Jackson 2018), increased liver enzymes (Jackson 2018; Lasso-de-la-Vega 2001)
Hypersensitivity: Anaphylaxis, angioedema (Chong 2021), drug reaction with eosinophilia and systemic symptoms (Ragucci 2001; Scaparotta 2011), hypersensitivity angiitis (Sahin 2008)
Infection: Parasitic infection (Lopez 2010)
Nervous system: Agitation (Childers 1997), coma (Abdennour 2017; Butler 2003; Dogukan 2006), encephalopathy (Beauvais 2015), movement disorder (Allford 2007; Attupurath 2009; Palomeras 2000; Pina 2005; Raju 2007; Rissardo 2023; Rohman 2014; Souzdalnitski 2014; Twardowschy 2008; Zesiewicz 2008), myoclonus (facial) (Hampton 2019; Hui 2019; Yeddi 2019), polyneuropathy (Gould 1998), stuttering (Nissani 1997), suicidal ideation (Molero 2019), suicidal tendencies (Molero 2019), visual hallucination (Parsons 2016)
Neuromuscular & skeletal: Increased creatine phosphokinase in blood specimen, rhabdomyolysis (Bilgir 2009; Choi 2017; Coupal 2017; Lipson 2005; Tuccori 2007)
Respiratory: Respiratory depression (FDA 2019)
Hypersensitivity to gabapentin or any component of the formulation
Disease-related concerns:
• Myasthenia gravis: Use with caution in patients with myasthenia gravis; may exacerbate condition (Mehrizi 2012).
• Renal impairment: Use with caution in patients with renal impairment; dose adjustment required.
• Seizure disorder: The safety and efficacy of the ER formulation has not been studied in patients with epilepsy.
• Substance abuse: Use with caution in patients with a history of substance abuse, including alcohol, benzodiazepines, cannabis, cocaine, and opioids; potential for drug dependency exists. Tolerance, psychological and physical dependence may occur (Evoy 2017; Mersfelder 2016).
Dosage form specific issues:
• Product interchangeability: IR and ER products are not interchangeable with each other or with gabapentin enacarbil due to differences in formulations, indications, and pharmacokinetics.
Other warnings/precautions:
• Tumorigenic potential: Male rat studies demonstrated an association with pancreatic adenocarcinoma (clinical implication in humans is unknown).
• Withdrawal: Antiseizure medications should not be discontinued abruptly because of the possibility of increasing seizure frequency in patients with epilepsy or other withdrawal symptoms (eg, confusion, irritability, tachycardia, diaphoresis). Therapy should be withdrawn gradually over ≥1 week to minimize the potential of increased seizure frequency, unless safety concerns require a more rapid withdrawal (Norton 2001; Tran 2005).
Withdrawal has been described following abrupt discontinuation of gabapentin in infants; reported symptoms included episodic tachycardia, emesis, and irritability; symptoms resolved after gabapentin was restarted. Avoid abrupt discontinuation, especially in patients on prolonged therapy (use >1 week); it has been recommended that gabapentin be continued even if patients are made nothing by mouth (NPO) (Carrasco 2015; Edwards 2016; McPherson 2021).
Bradycardia has been reported in infants receiving gabapentin. A case series reported bradycardia occurred within 24 hours of initiation of gabapentin in former 26-week GA twins; the dose was lowered with resolution of bradycardia in one twin; the other twin had gabapentin discontinued without a trial of a lower dose (Edwards 2016). Another case series reported bradycardia in 3 infants; however, all infants were also receiving other medications known to increase risk of bradycardia; following a reduction in the gabapentin dose, bradycardia resolved (O'Mara 2018). Patients should be monitored closely.
Excipient information presented when available (limited, particularly for generics); consult specific product labeling.
Capsule, Oral:
Neurontin: 100 mg, 300 mg, 400 mg
Generic: 100 mg, 300 mg, 400 mg
Solution, Oral:
Neurontin: 250 mg/5 mL (470 mL) [strawberry anise flavor]
Generic: 250 mg/5 mL (473 mL); 250 mg/5 mL (5 mL, 6 mL, 470 mL)
Tablet, Oral:
Gralise: 450 mg, 750 mg, 900 mg
Neurontin: 600 mg, 800 mg [scored]
Generic: 600 mg, 800 mg
Tablet, Oral, Extended Release:
Gralise: 300 mg [contains soybean lecithin]
Gralise: 600 mg
Generic: 300 mg, 600 mg
Yes
Capsules (Gabapentin Oral)
100 mg (per each): $0.11 - $0.61
300 mg (per each): $0.15 - $2.67
400 mg (per each): $0.03 - $1.61
Capsules (Neurontin Oral)
100 mg (per each): $3.31
300 mg (per each): $8.27
400 mg (per each): $9.92
Misc (Gralise Oral)
300 (9) &600(24) MG (per each): $0.00
Solution (Gabapentin Oral)
250 mg/5 mL (per mL): $0.32 - $0.83
Solution (Neurontin Oral)
250 mg/5 mL (per mL): $1.25
Tablets (Gabapentin Oral)
600 mg (per each): $0.07 - $2.53
800 mg (per each): $0.11 - $3.05
Tablets (Gralise Oral)
300 mg (per each): $12.77
450 mg (per each): $12.77
600 mg (per each): $12.77
750 mg (per each): $19.15
900 mg (per each): $19.15
Tablets (Neurontin Oral)
600 mg (per each): $15.71
800 mg (per each): $18.85
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.
Capsule, Oral:
Neurontin: 100 mg, 300 mg, 400 mg [contains corn starch, fd&c blue #2 (indigotine,indigo carmine)]
Generic: 100 mg, 300 mg, 400 mg
Tablet, Oral:
Neurontin: 600 mg, 800 mg [contains corn starch]
Generic: 600 mg, 800 mg
Oral:
Immediate release: May administer without regards to meals. Administer first dose on first day at bedtime to avoid somnolence and dizziness. Dosage must be adjusted for renal function; when given 3 times daily, the maximum time between doses should not exceed 12 hours. Capsules may be opened and sprinkled on food (eg, applesauce, orange juice, pudding) for patients unable to swallow capsules (Ref).
Extended release: Administer with evening meal. Swallow whole; do not chew, crush, or split.
Oral: Immediate release: Capsule, tablet, oral solution: May consider administration of first dose on first day at bedtime to avoid somnolence and dizziness. May be administered without regard to meals; administration with meals may decrease adverse GI effects. Dose may be administered as combination of dosage forms; do not administer within 2 hours of magnesium- or aluminum-containing antacids. When given 3 times daily, the maximum time between doses should not exceed 12 hours. Capsule should be administered with plenty of water to ensure complete swallowing. Although the manufacturer recommends swallowing capsules whole, some centers have opened the capsules and mixed the contents in drinks (eg, orange juice) or food (eg, applesauce) when necessary (Ref). The 600 mg and 800 mg tablets are scored and may be split if a half-tablet is needed; manufacturer recommends that half tablets not used within 28 days of breaking the scored tablets should be discarded.
An FDA-approved patient medication guide, which is available with the product information and as follows, must be dispensed with this medication:
Gralise: https://www.accessdata.fda.gov/drugsatfda_docs/label/2023/022544s029lbl.pdf#page=21
Postherpetic neuralgia: Management of postherpetic neuralgia (PHN) in adults.
Seizures, focal (partial) onset (immediate release only): As adjunctive therapy in the treatment of focal (partial) seizures with and without secondary generalization in adults and pediatric patients 3 years of age and older with epilepsy.
Alcohol use disorder, moderate to severe (alternative agent); Alcohol withdrawal; Cough, chronic refractory; Generalized anxiety disorder; Fibromyalgia (alternative agent); Hiccups (singultus); Neuropathic pain (other than postherpetic neuralgia); Pruritus, chronic (neuropathic or malignancy related) (alternative agent); Pruritus, uremic; Restless legs syndrome; Social anxiety disorder, adjunct to antidepressants or monotherapy (alternative agent); Vasomotor symptoms associated with menopause
Gabapentin may be confused with gabapentin enacarbil, gemfibrozil
Neurontin may be confused with Motrin, Neoral, nitrofurantoin, Noroxin [DSC], Zarontin
The Institute for Safe Medication Practices (ISMP) includes this medication (when used for neuropathic pain) among its list of drugs that have a heightened risk of causing significant patient harm when used in error.
Substrate of OCT2
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 Lexicomp drug interactions program by clicking on the “Launch drug interactions program” link above.
Alcohol (Ethyl): CNS Depressants may enhance the CNS depressant effect of Alcohol (Ethyl). Risk C: Monitor therapy
Alizapride: May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Aluminum Hydroxide: May decrease the serum concentration of Gabapentin. Management: Administer gabapentin at least 2 hours after administration of antacids containing aluminum hydroxide or magnesium hydroxide. Risk D: Consider therapy modification
Azelastine (Nasal): May enhance the CNS depressant effect of CNS Depressants. Risk X: Avoid combination
Blonanserin: CNS Depressants may enhance the CNS depressant effect of Blonanserin. Management: Use caution if coadministering blonanserin and CNS depressants; dose reduction of the other CNS depressant may be required. Strong CNS depressants should not be coadministered with blonanserin. Risk D: Consider therapy modification
Brexanolone: CNS Depressants may enhance the CNS depressant effect of Brexanolone. Risk C: Monitor therapy
Brimonidine (Topical): May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Bromopride: May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Bromperidol: May enhance the CNS depressant effect of CNS Depressants. Risk X: Avoid combination
Buprenorphine: CNS Depressants may enhance the CNS depressant effect of Buprenorphine. Management: Consider reduced doses of other CNS depressants, and avoiding such drugs in patients at high risk of buprenorphine overuse/self-injection. Initiate buprenorphine at lower doses in patients already receiving CNS depressants. Risk D: Consider therapy modification
Cannabinoid-Containing Products: CNS Depressants may enhance the CNS depressant effect of Cannabinoid-Containing Products. Risk C: Monitor therapy
Cetirizine (Systemic): May enhance the CNS depressant effect of Gabapentin. Cetirizine (Systemic) may decrease the serum concentration of Gabapentin. Risk C: Monitor therapy
Chlormethiazole: May enhance the CNS depressant effect of CNS Depressants. Management: Monitor closely for evidence of excessive CNS depression. The chlormethiazole labeling states that an appropriately reduced dose should be used if such a combination must be used. Risk D: Consider therapy modification
Chlorphenesin Carbamate: May enhance the adverse/toxic effect of CNS Depressants. Risk C: Monitor therapy
CNS Depressants: May enhance the adverse/toxic effect of other CNS Depressants. Risk C: Monitor therapy
Daridorexant: May enhance the CNS depressant effect of CNS Depressants. Management: Dose reduction of daridorexant and/or any other CNS depressant may be necessary. Use of daridorexant with alcohol is not recommended, and the use of daridorexant with any other drug to treat insomnia is not recommended. Risk D: Consider therapy modification
Desmopressin: Hyponatremia-Associated Agents may enhance the hyponatremic effect of Desmopressin. Risk C: Monitor therapy
DexmedeTOMIDine: CNS Depressants may enhance the CNS depressant effect of DexmedeTOMIDine. Management: Monitor for increased CNS depression during coadministration of dexmedetomidine and CNS depressants, and consider dose reductions of either agent to avoid excessive CNS depression. Risk D: Consider therapy modification
Difelikefalin: May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Dimethindene (Topical): May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Doxylamine: CNS Depressants may enhance the CNS depressant effect of Doxylamine. Risk C: Monitor therapy
DroPERidol: May enhance the CNS depressant effect of CNS Depressants. Management: Consider dose reductions of droperidol or of other CNS agents (eg, opioids, barbiturates) with concomitant use. Risk D: Consider therapy modification
Esketamine: May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Flunarizine: CNS Depressants may enhance the CNS depressant effect of Flunarizine. Risk X: Avoid combination
Flunitrazepam: CNS Depressants may enhance the CNS depressant effect of Flunitrazepam. Management: Reduce the dose of CNS depressants when combined with flunitrazepam and monitor patients for evidence of CNS depression (eg, sedation, respiratory depression). Use non-CNS depressant alternatives when available. Risk D: Consider therapy modification
HydrOXYzine: May enhance the CNS depressant effect of CNS Depressants. Management: Consider a decrease in the CNS depressant dose, as appropriate, when used together with hydroxyzine. Increase monitoring of signs/symptoms of CNS depression in any patient receiving hydroxyzine together with another CNS depressant. Risk D: Consider therapy modification
Ixabepilone: May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Kava Kava: May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Kratom: May enhance the CNS depressant effect of CNS Depressants. Risk X: Avoid combination
Lemborexant: May enhance the CNS depressant effect of CNS Depressants. Management: Dosage adjustments of lemborexant and of concomitant CNS depressants may be necessary when administered together because of potentially additive CNS depressant effects. Close monitoring for CNS depressant effects is necessary. Risk D: Consider therapy modification
LevETIRAcetam: May enhance the CNS depressant effect of Gabapentin. Risk C: Monitor therapy
Lisuride: May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Lofexidine: May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Magnesium Salts: May enhance the CNS depressant effect of Gabapentin. Specifically, high dose intravenous/epidural magnesium sulfate may enhance the CNS depressant effects of gabapentin. Magnesium Salts may decrease the serum concentration of Gabapentin. Management: Administer gabapentin at least 2 hours after use of a magnesium-containing antacid. Monitor patients closely for evidence of reduced response to gabapentin therapy. Monitor for CNS depression if high dose IV/epidural magnesium sulfate is used. Risk D: Consider therapy modification
Mefloquine: May diminish the therapeutic effect of Antiseizure Agents. Mefloquine may decrease the serum concentration of Antiseizure Agents. Management: Mefloquine is contraindicated for malaria prophylaxis in persons with a history of seizures. If antiseizure drugs are being used for another indication, monitor antiseizure drug concentrations and treatment response closely with concurrent use. Risk D: Consider therapy modification
Methotrimeprazine: CNS Depressants may enhance the CNS depressant effect of Methotrimeprazine. Methotrimeprazine may enhance the CNS depressant effect of CNS Depressants. Management: Reduce the usual dose of CNS depressants by 50% if starting methotrimeprazine until the dose of methotrimeprazine is stable. Monitor patient closely for evidence of CNS depression. Risk D: Consider therapy modification
Metoclopramide: May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
MetyraPONE: Antiseizure Agents may diminish the diagnostic effect of MetyraPONE. Management: Consider alternatives to the use of the metyrapone test in patients taking antiseizure agents. Risk D: Consider therapy modification
MetyroSINE: CNS Depressants may enhance the sedative effect of MetyroSINE. Risk C: Monitor therapy
Mianserin: May diminish the therapeutic effect of Antiseizure Agents. Risk C: Monitor therapy
Minocycline (Systemic): May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Nabilone: May enhance the CNS depressant effect of CNS Depressants. Risk X: Avoid combination
Olopatadine (Nasal): May enhance the CNS depressant effect of CNS Depressants. Risk X: Avoid combination
Opioid Agonists: CNS Depressants may enhance the CNS depressant effect of Opioid Agonists. Management: Avoid concomitant use of opioid agonists and benzodiazepines or other CNS depressants when possible. These agents should only be combined if alternative treatment options are inadequate. If combined, limit the dosages and duration of each drug. Risk D: Consider therapy modification
Orlistat: May decrease the serum concentration of Antiseizure Agents. Risk C: Monitor therapy
Orphenadrine: CNS Depressants may enhance the CNS depressant effect of Orphenadrine. Risk X: Avoid combination
Oxomemazine: May enhance the CNS depressant effect of CNS Depressants. Risk X: Avoid combination
Oxybate Salt Products: CNS Depressants may enhance the CNS depressant effect of Oxybate Salt Products. Management: Consider alternatives to this combination when possible. If combined, dose reduction or discontinuation of one or more CNS depressants (including the oxybate salt product) should be considered. Interrupt oxybate salt treatment during short-term opioid use Risk D: Consider therapy modification
OxyCODONE: CNS Depressants may enhance the CNS depressant effect of OxyCODONE. Management: Avoid concomitant use of oxycodone and benzodiazepines or other CNS depressants when possible. These agents should only be combined if alternative treatment options are inadequate. If combined, limit the dosages and duration of each drug. Risk D: Consider therapy modification
Paraldehyde: CNS Depressants may enhance the CNS depressant effect of Paraldehyde. Risk X: Avoid combination
Perampanel: May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Piribedil: CNS Depressants may enhance the CNS depressant effect of Piribedil. Risk C: Monitor therapy
Pramipexole: CNS Depressants may enhance the sedative effect of Pramipexole. Risk C: Monitor therapy
Procarbazine: May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Ropeginterferon Alfa-2b: CNS Depressants may enhance the adverse/toxic effect of Ropeginterferon Alfa-2b. Specifically, the risk of neuropsychiatric adverse effects may be increased. Management: Avoid coadministration of ropeginterferon alfa-2b and other CNS depressants. If this combination cannot be avoided, monitor patients for neuropsychiatric adverse effects (eg, depression, suicidal ideation, aggression, mania). Risk D: Consider therapy modification
ROPINIRole: CNS Depressants may enhance the sedative effect of ROPINIRole. Risk C: Monitor therapy
Rotigotine: CNS Depressants may enhance the sedative effect of Rotigotine. Risk C: Monitor therapy
Rufinamide: May enhance the adverse/toxic effect of CNS Depressants. Specifically, sleepiness and dizziness may be enhanced. Risk C: Monitor therapy
Suvorexant: CNS Depressants may enhance the CNS depressant effect of Suvorexant. Management: Dose reduction of suvorexant and/or any other CNS depressant may be necessary. Use of suvorexant with alcohol is not recommended, and the use of suvorexant with any other drug to treat insomnia is not recommended. Risk D: Consider therapy modification
Thalidomide: CNS Depressants may enhance the CNS depressant effect of Thalidomide. Risk X: Avoid combination
Trimeprazine: May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Valerian: May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Zolpidem: CNS Depressants may enhance the CNS depressant effect of Zolpidem. Management: Reduce the Intermezzo brand sublingual zolpidem adult dose to 1.75 mg for men who are also receiving other CNS depressants. No such dose change is recommended for women. Avoid use with other CNS depressants at bedtime; avoid use with alcohol. Risk D: Consider therapy modification
Zuranolone: May enhance the CNS depressant effect of CNS Depressants. Management: Consider alternatives to the use of zuranolone with other CNS depressants or alcohol. If combined, consider a zuranolone dose reduction and monitor patients closely for increased CNS depressant effects. Risk D: Consider therapy modification
Tablet, solution (immediate release): No significant effect on rate or extent of absorption; extended release tablet: Increases rate and extent of absorption. Management: Administer immediate release products without regard to food. Administer extended release with food.
Evaluate pregnancy status prior to use. Pregnancy testing is recommended before treating acute alcohol withdrawal symptoms (ASAM 2020).
Folic acid supplementation is recommended prior to becoming pregnant during gabapentin therapy (Borgelt 2016; Picchietti 2015).
Gabapentin crosses the placenta (Ohman 2005; Ohman 2009).
Outcome data following maternal use of gabapentin during pregnancy are available (Blotière 2019; Blotière 2020; Hernández-Díaz 2012; Holmes 2012; Mostacci 2018; Patorno 2020; Westin 2016). Folic acid supplementation is recommended during pregnancy in patients using gabapentin (Borgelt 2016; Picchietti 2015).
Adequate data are not available to determine if pregnancy-induced physiologic changes alter gabapentin pharmacokinetic properties in a clinically significant way (Arfman 2020; Tomson 2019). Consider measuring the total gabapentin serum trough concentrations prior to conception during a period of stable seizure control and repeat during pregnancy and postpartum if dosage adjustments are needed to maintain seizure control (Arfman 2020).
Gabapentin is used off-label for the treatment of restless leg syndrome; however, current guidelines note there is insufficient evidence to recommend its use in pregnant patients for this indication (Picchietti 2015). Pharmacological agents should not be used for the treatment of alcohol use disorder during pregnancy unless needed for the treatment of acute alcohol withdrawal or a coexisting disorder; agents other than gabapentin may be preferred when treatment is needed (APA [Reus 2018]; ASAM 2020).
Data collection to monitor pregnancy and infant outcomes following exposure to gabapentin is ongoing. Patients exposed to gabapentin during pregnancy are encouraged to enroll in the North American Antiepileptic Drug (NAAED) Pregnancy Registry by calling 1-888-233-2334. Additional information is available at www.aedpregnancyregistry.org.
Gabapentin is present in breast milk.
Data related to the presence of in gabapentin in breast milk are limited (Tomson 2022):
• Data are available from 5 mother infant pairs, 14 to 97 days postpartum. In all cases, maternal use of gabapentin occurred during pregnancy and continued after delivery (dosage range 600 to 2100 mg/day). Breast milk samples were obtained prior to the morning dose and concentrations ranged from 7 to 51 µM (1.2 to 8.7 mcg/mL). After nursing, gabapentin was present in the serum of 3 infants and below the limit of quantification in a fourth infant (<4 µM; 0.7 mcg/mL); one infant was not breastfed. The authors of the study calculated the estimated daily infant dose of gabapentin via breast milk to be 0.2 to 1.3 mg/kg/day providing a relative infant dose (RID) of 1.3 to 3.8% compared to weight-adjusted maternal dose. Adverse events were not reported in the breastfed infants (Ohman 2005).
• Data are also available from a patient 1.6 months postpartum taking gabapentin 600 mg 3 times daily for 6 weeks. Breast milk was sampled at intervals over ~23 hours after the maternal dose. Using the average breast milk concentration of 5.7 mcg/mL, the authors of the study calculated the estimated daily infant dose of gabapentin via breast milk to be 0.86 mg/kg/day, providing a RID of 2.34% compared to weight-adjusted maternal dose. The infant was breastfed 6 to 7 times daily and provided supplementary feedings at night; his plasma concentration of gabapentin was 0.4 mg/L (Kristensen 2006).
• The average gabapentin breast milk/maternal serum concentration ratios in these studies was 1.0 (Tomson 2022).
• In general, breastfeeding is considered acceptable when the RID is <10% (Anderson 2016; Ito 2000).
According to the manufacturer, the decision to breastfeed during therapy should consider the risk of infant exposure, the benefits of breastfeeding to the infant, and benefits of treatment to the mother. Based on limited data, gabapentin is considered relatively compatible with breastfeeding; infants should be monitored for drowsiness, adequate weight gain, and developmental milestones (Davanzo 2013; Veiby 2015). Available guidelines state gabapentin may be considered for the treatment of refractory restless leg syndrome in persons who are breastfeeding (Picchietti 2015). Pharmacological agents should not be used for the treatment of alcohol use disorder in breastfeeding patients unless needed for the treatment of acute alcohol withdrawal or a coexisting disorder (APA [Reus 2018]).
Extended release tablet should be taken with food.
Periodic renal function, suicidality (eg, suicidal thoughts, depression, behavioral changes); mental alertness; symptoms of respiratory depression and sedation in patients with underlying respiratory disease (FDA 2019); signs and symptoms of hypersensitivity (eg. anaphylaxis/angioedema, or possible disparate manifestations associated with lymphatic, hepatic, renal, cardiac, and/or hematologic systems; fever, rash, and/or eosinophilia).
Gabapentin is structurally related to GABA. However, it does not bind to GABAA or GABAB receptors, and it does not appear to influence degradation or uptake of GABA. High affinity gabapentin binding sites have been located throughout the brain; these sites correspond to the presence of voltage-gated calcium channels specifically possessing the alpha-2-delta-1 subunit. This channel appears to be located presynaptically, and may modulate the release of excitatory neurotransmitters which participate in epileptogenesis and nociception. These effects on restless leg syndrome are unknown.
Absorption: Variable, from proximal small bowel by L-amino transport system; saturable process; dose-dependent
Distribution: Vd: 58 ± 6 L; CSF concentrations are ~20% of plasma concentrations
Protein binding: <3%
Metabolism: Not metabolized
Bioavailability: Inversely proportional to dose due to saturable absorption:
Immediate release:
900 mg/day: 60%
1,200 mg/day: 47%
2,400 mg/day: 34%
3,600 mg/day: 33%
4,800 mg/day: 27%
Extended release: Variable; increased with higher fat content meal
Half-life elimination:
Infants 1 month to Children 12 years: 4.7 hours
Adults, normal: 5 to 7 hours; increased half-life with decreased renal function; anuric adult patients: 132 hours; adults during hemodialysis: 3.8 hours
Time to peak: Immediate release: Infants 1 month to Children 12 years: 2 to 3 hours; Adults: 2 to 4 hours; Extended release: 8 hours
Excretion: Proportional to renal function; urine (as unchanged drug)
Clearance: Apparent oral clearance is directly proportional to CrCl: Clearance in infants is highly variable; oral clearance (per kg) in children <5 years of age is higher than in children ≥5 years of age
Altered kidney function: Adults: In CrCl <30 mL/minute, half-life is approximately 52 hours (immediate release). In moderate and severe renal impairment, Cl was decreased to 3 and 1 L/hour, respectively, compared with 5 to 7 L/hour in nonrenal impairment patients (ER).
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