Gabapentin
Capsule · Oral
Uses
Gabapentin is indicated for:
• Management of postherpetic neuralgia in adults
• Adjunctive therapy in the treatment of partial onset seizures, with and without secondary generalization, in adults and pediatric patients 3 years and older with epilepsy Gabapentin is indicated for:
• Postherpetic neuralgia in adults ( 1 )
• Adjunctive therapy in the treatment of partial onset seizures, with and without secondary generalization, in adults and pediatric patients 3 years and older with epilepsy ( 1 )
Dosage and administration
• Postherpetic Neuralgia ( 2.1 ) o Dose can be titrated up as needed to a dose of 1800 mg/day o Day 1: Single 300 mg dose o Day 2: 600 mg/day (i.e., 300 mg two times a day) o Day 3: 900 mg/day (i.e., 300 mg three times a day)
• Epilepsy with Partial Onset Seizures ( 2.2 ) o Patients 12 years of age and older: starting dose is 300 mg three times daily; may be titrated up to 600 mg three times daily o Patients 3 to 11 years of age: starting dose range is 10 to 15 mg/kg/day, given in three divided doses; recommended dose in patients 3 to 4 years of age is 40 mg/kg/day, given in three divided doses; the recommended dose in patients 5 to 11 years of age is 25 to 35 mg/kg/day, given in three divided doses. The recommended dose is reached by upward titration over a period of approximately 3 days
• Dose should be adjusted in patients with reduced renal function ( 2.3 , 2.4 ) 2.1 Dosage for Postherpetic Neuralgia In adults with postherpetic neuralgia, gabapentin may be initiated on Day 1 as a single 300 mg dose, on Day 2 as 600 mg/day (300 mg two times a day), and on Day 3 as 900 mg/day (300 mg three times a day). The dose can subsequently be titrated up as needed for pain relief to a dose of 1800 mg/day (600 mg three times a day). In clinical studies, efficacy was demonstrated over a range of doses from 1800 mg/day to 3600 mg/day with comparable effects across the dose range; however, in these clinical studies, the additional benefit of using doses greater than 1800 mg/day was not demonstrated. 2.2 Dosage for Epilepsy with Partial Onset Seizures Patients 12 Years of Age and Above The starting dose is 300 mg three times a day. The recommended maintenance dose of gabapentin is 300 mg to 600 mg three times a day. Dosages up to 2400 mg/day have been administered in long-term clinical studies. Doses of 3600 mg/day have also been administered to a small number of patients for a relatively short duration. Administer gabapentin three times a day using 300 mg or 400 mg capsules, or 600 mg or 800 mg tablets. The maximum time between doses should not exceed 12 hours. Pediatric Patients Age 3 to 11 Years The starting dose range is 10 mg/kg/day to 15 mg/kg/day, given in three divided doses, and the recommended maintenance dose reached by upward titration over a period of approximately 3 days. The recommended maintenance dose of gabapentin in patients 3 to 4 years of age is 40 mg/kg/day, given in three divided doses. The recommended maintenance dose of gabapentin in patients 5 to 11 years of age is 25 mg/kg/day to 35 mg/kg/day, given in three divided doses. Gabapentin may be administered as the oral solution, capsule, or tablet, or using combinations of these formulations. Dosages up to 50 mg/kg/day have been administered in a long-term clinical study. The maximum time interval between doses should not exceed 12 hours. 2.3 Dosage Adjustment in Patients with Renal Impairment Dosage adjustment in patients 12 years of age and older with renal impairment or undergoing hemodialysis is recommended, as follows (see dosing recommendations above for effective doses in each indication): TABLE 1. Gabapentin Dosage Based on Renal Function TID = Three times a day; BID = Two times a day; QD = Single daily dose Renal Function Creatinine Clearance (mL/min) Total Daily Dose Range (mg/day) Dose Regimen (mg) ≥ 60 900 to 3600 300 TID 400 TID 600 TID 800 TID 1200 TID >30 to 59 400 to 1400 200 BID 300 BID 400 BID 500 BID 700 BID >15 to 29 200 to 700 200 QD 300 QD 400 QD 500 QD 700 QD 15 For patients with creatinine clearance <15 mL/min, reduce daily dose in proportion to creatinine clearance (e.g., patients with a creatinine clearance of 7.5 mL/min should receive one-half the daily dose that patients with a creatinine clearance of 15 mL/min receive). 100 to 300 100 QD 125 QD 150 QD 200 QD 300 QD Post-Hemodialysis Supplemental Dose (mg) Patients on hemodialysis should receive maintenance doses based on estimates of creatinine clearance as indicated in the upper portion of the table and a supplemental post-hemodialysis dose administered after each 4 hours of hemodialysis as indicated in the lower portion of the table. Hemodialysis 125 150 200 250 350 Creatinine clearance (CLCr) is difficult to measure in outpatients. In patients with stable renal function, creatinine clearance can be reasonably well estimated using the equation of Cockcroft and Gault: The use of gabapentin in patients less than 12 years of age with compromised renal function has not been studied. Cockcroft and Gault Equation 2.4 Dosage in Elderly Because elderly patients are more likely to have decreased renal function, care should be taken in dose selection, and dose should be adjusted based on creatinine clearance values in these patients. 2.5 Administration Information Administer gabapentin orally with or without food. If the gabapentin dose is reduced, discontinued, or substituted with an alternative medication, this should be done gradually over a minimum of 1 week (a longer period may be needed at the discretion of the prescriber).
Dosage forms and strengths
Oral solution
• 250 mg per 5 mL (50 mg per mL), clear colorless to slightly yellow solution
• Oral Solution: 250 mg/5mL ( 3 )
Contraindications
Gabapentin is contraindicated in patients who have demonstrated hypersensitivity to the drug or its ingredients. Known hypersensitivity to gabapentin or its ingredients ( 4 )
Warnings and precautions
• Drug Reaction with Eosinophilia and Systemic Symptoms (Multiorgan hypersensitivity): Discontinue if alternative etiology is not established ( 5.1 )
• Anaphylaxis and Angioedema: Discontinue and evaluate patient immediately ( 5.2 )
• Driving Impairment; Somnolence/Sedation and Dizziness: Warn patients not to drive until they have gained sufficient experience to assess whether their ability to drive or operate heavy machinery will be impaired ( 5.3 , 5.4 )
• Suicidal Behavior and Ideation: Monitor for suicidal thoughts/behavior ( 5.5 )
• Abrupt or rapid discontinuation may increase the risk for seizures. Withdrawal symptoms, or suicidal behavior and ideation have been observed after discontinuation ( 5.6 )
• Respiratory Depression: May occur with gabapentin when used with concomitant central nervous system (CNS) depressants, including opioids, or in the setting of underlying respiratory impairment. Monitor patients and adjust dosage as appropriate ( 5.8 )
• Neuropsychiatric Adverse Reactions in Children 3 to 12 Years of Age: Monitor for such events ( 5.9 ) 5.1 Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS)/Multiorgan Hypersensitivity Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS), also known as multiorgan hypersensitivity, has occurred with gabapentin. Some of these reactions have been fatal or life-threatening. DRESS typically, although not exclusively, presents with fever, rash, and/or lymphadenopathy, in association with other organ system involvement, such as hepatitis, nephritis, hematological abnormalities, myocarditis, or myositis sometimes resembling an acute viral infection. Eosinophilia is often present. This disorder is variable in its expression, and other organ systems not noted here may be involved. It is important to note that early manifestations of hypersensitivity, such as fever or lymphadenopathy, may be present even though rash is not evident. If such signs or symptoms are present, the patient should be evaluated immediately. Gabapentin should be discontinued if an alternative etiology for the signs or symptoms cannot be established. 5.2 Anaphylaxis and Angioedema Gabapentin can cause anaphylaxis and angioedema after the first dose or at any time during treatment. Signs and symptoms in reported cases have included difficulty breathing, swelling of the lips, throat, and tongue, and hypotension requiring emergency treatment. Patients should be instructed to discontinue gabapentin and seek immediate medical care should they experience signs or symptoms of anaphylaxis or angioedema. 5.3 Effects on Driving and Operating Heavy Machinery Patients taking gabapentin should not drive until they have gained sufficient experience to assess whether gabapentin impairs their ability to drive. Driving performance studies conducted with a prodrug of gabapentin (gabapentin enacarbil tablet, extended-release) indicate that gabapentin may cause significant driving impairment. Prescribers and patients should be aware that patients’ ability to assess their own driving competence, as well as their ability to assess the degree of somnolence caused by gabapentin, can be imperfect. The duration of driving impairment after starting therapy with gabapentin is unknown. Whether the impairment is related to somnolence [see Warnings and Precautions (5.4) ] or other effects of gabapentin is unknown. Moreover, because gabapentin causes somnolence and dizziness [see Warnings and Precautions (5.4) ] , patients should be advised not to operate complex machinery until they have gained sufficient experience on gabapentin to assess whether gabapentin impairs their ability to perform such tasks. 5.4 Somnolence/Sedation and Dizziness During the controlled epilepsy trials in patients older than 12 years of age receiving doses of gabapentin up to 1800 mg daily, somnolence, dizziness, and ataxia were reported at a greater rate in patients receiving gabapentin compared to placebo: i.e., 19% in drug versus 9% in placebo for somnolence, 17% in drug versus 7% in placebo for dizziness, and 13% in drug versus 6% in placebo for ataxia. In these trials somnolence, ataxia and fatigue were common adverse reactions leading to discontinuation of gabapentin in patients older than 12 years of age, with 1.2%, 0.8% and 0.6% discontinuing for these events, respectively. During the controlled trials in patients with post-herpetic neuralgia, somnolence, and dizziness were reported at a greater rate compared to placebo in patients receiving gabapentin, in dosages up to 3600 mg per day: i.e., 21% in gabapentin-treated patients versus 5% in placebo-treated patients for somnolence and 28% in gabapentin-treated patients versus 8% in placebo-treated patients for dizziness. Dizziness and somnolence were among the most common adverse reactions leading to discontinuation of gabapentin. Patients should be carefully observed for signs of central nervous system (CNS) depression, such as somnolence and sedation, when gabapentin is used with other drugs with sedative properties because of potential synergy. In addition, patients who require concomitant treatment with morphine may experience increases in gabapentin concentrations and may require dose adjustment [see Drug Interactions (7.1) ] . 5.5 Suicidal Behavior and Ideation Antiepileptic drugs (AEDs), including gabapentin, increase the risk of suicidal thoughts or behavior in patients taking these drugs for any indication. Suicidal behavior and ideation have also been reported in patients after discontinuation of gabapentin [see Warnings and Precautions (5.6) ] . Patients treated with any AED for any indication should be monitored for the emergence or worsening of depression, suicidal thoughts or behavior, and/or any unusual changes in mood or behavior.
Side effects
The following serious adverse reactions are discussed in greater detail in other sections:
• Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS)/Multiorgan Hypersensitivity [see Warnings and Precautions (5.1) ]
• Anaphylaxis and Angioedema [see Warnings and Precautions (5.2) ]
• Somnolence/Sedation and Dizziness [see Warnings and Precautions (5.4) ]
• Suicidal Behavior and Ideation [see Warnings and Precautions (5.5) ]
• Increased Risk of Seizures and Other Adverse Reactions with Abrupt or Rapid Discontinuation [see Warnings and Precautions (5.6) ]
• Status Epilepticus [see Warnings and Precautions (5.7) ]
• Respiratory Depression [see Warnings and Precautions (5.8) ]
• Neuropsychiatric Adverse Reactions (Pediatric Patients 3 to 12 Years of Age) [see Warnings and Precautions (5.9) ] Most common adverse reactions (incidence ≥8% and at least twice that for placebo) were:
• Postherpetic neuralgia: Dizziness, somnolence, and peripheral edema ( 6.1 )
• Epilepsy in patients >12 years of age: Somnolence, dizziness, ataxia, fatigue, and nystagmus ( 6.1 )
• Epilepsy in patients 3 to 12 years of age: Viral infection, fever, nausea and/or vomiting, somnolence, and hostility ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Viatris at 1-877-446-3679 (1-877-4-INFO-RX) or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. Postherpetic Neuralgia The most common adverse reactions associated with the use of gabapentin in adults, not seen at an equivalent frequency among placebo-treated patients, were dizziness, somnolence, and peripheral edema. In the 2 controlled trials in postherpetic neuralgia, 16% of the 336 patients who received gabapentin and 9% of the 227 patients who received placebo discontinued treatment because of an adverse reaction. The adverse reactions that most frequently led to withdrawal in gabapentin-treated patients were dizziness, somnolence, and nausea. Table 3 lists adverse reactions that occurred in at least 1% of gabapentin-treated patients with postherpetic neuralgia participating in placebo-controlled trials and that were numerically more frequent in the gabapentin group than in the placebo group. TABLE 3. Adverse Reactions in Pooled Placebo-Controlled Trials in Postherpetic Neuralgia Gabapentin N=336 % Placebo N=227 % Body as a Whole Asthenia 6 5 Infection 5 4 Accidental injury 3 1 Digestive System Diarrhea 6 3 Dry mouth 5 1 Constipation 4 2 Nausea 4 3 Vomiting 3 2 Metabolic and Nutritional Disorders Peripheral edema 8 2 Weight gain 2 0 Hyperglycemia 1 0 Nervous System Dizziness 28 8 Somnolence 21 5 Ataxia 3 0 Abnormal thinking 3 0 Abnormal gait 2 0 Incoordination 2 0 Respiratory System Pharyngitis 1 0 Special Senses Amblyopia Reported as blurred vision 3 1 Conjunctivitis 1 0 Diplopia 1 0 Otitis media 1 0 Other reactions in more than 1% of patients but equally or more frequent in the placebo group included pain, tremor, neuralgia, back pain, dyspepsia, dyspnea, and flu syndrome. There were no clinically important differences between men and women in the types and incidence of adverse reactions. Because there were few patients whose race was reported as other than white, there are insufficient data to support a statement regarding the distribution of adverse reactions by race. Epilepsy with Partial Onset Seizures (Adjunctive Therapy) The most common adverse reactions with gabapentin in combination with other antiepileptic drugs in patients >12 years of age, not seen at an equivalent frequency among placebo-treated patients, were somnolence, dizziness, ataxia, fatigue, and nystagmus. The most common adverse reactions with gabapentin in combination with other antiepileptic drugs in pediatric patients 3 to 12 years of age, not seen at an equal frequency among placebo-treated patients, were viral infection, fever, nausea and/or vomiting, somnolence, and hostility [see Warnings and Precautions (5.9) ] . Approximately 7% of the 2074 patients >12 years of age and approximately 7% of the 449 pediatric patients 3 to 12 years of age who received gabapentin in premarketing clinical trials discontinued treatment because of an adverse reaction. The adverse reactions most commonly associated with withdrawal in patients >12 years of age were somnolence (1.2%), ataxia (0.8%), fatigue (0.6%), nausea and/or vomiting (0.6%), and dizziness (0.6%). The adverse reactions most commonly associated with withdrawal in pediatric patients were emotional lability (1.6%), hostility (1.3%), and hyperkinesia (1.1%). Table 4 lists adverse reactions that occurred in at least 1% of gabapentin-treated patients >12 years of age with epilepsy participating in placebo-controlled trials and were numerically more common in the gabapentin group. In these studies, either gabapentin or placebo was added to the patient’s current antiepileptic drug therapy. TABLE 4. Adverse Reactions in Pooled Placebo-Controlled Add-On Trials in Epilepsy Patients >12 Years of Age Gabapentin Plus background antiepileptic drug therapy N=543 % Placebo N=378 % Body as a Whole Fatigue 11 5 Increased weight 3 2 Back pain 2 1 Peripheral edema 2 1 Cardiovascular Vasodilatation 1 0 Digestive System Dyspepsia 2 1 Dry mouth or throat 2 1 Constipation 2 1 Dental abnormalities 2 0 Nervous System Somnolence 19 9 Dizziness 17 7 Ataxia 13 6 Nystagmus 8 4 Tremor 7 3 Dysarthria 2 1 Amnesia 2 0 Depression 2 1 Abnormal thinking 2 1 Abnormal coordination 1 0 Respiratory System Pharyngitis 3 2 Coughing 2 1 Skin and Appendages Abrasion 1 0 Urogenital System Impotence 2 1 Special Senses Diplopia 6 2 Amblyopia Amblyopia was often described as blurred vision.
Drug interactions
Concentrations increased by morphine; may need dose adjustment ( 5.4 , 7.1 ) 7.1 Opioids Respiratory depression and sedation, sometimes resulting in death, have been reported following coadministration of gabapentin with opioids (e.g., morphine, hydrocodone, oxycodone, buprenorphine) [see Warnings and Precautions (5.8) ] . Hydrocodone Coadministration of gabapentin with hydrocodone decreases hydrocodone exposure [see Clinical Pharmacology (12.3) ] . The potential for alteration in hydrocodone exposure and effect should be considered when gabapentin is started or discontinued in a patient taking hydrocodone. Morphine When gabapentin is administered with morphine, patients should be observed for signs of CNS depression, such as somnolence, sedation and respiratory depression [see Clinical Pharmacology (12.3) ] . 7.2 Other Antiepileptic Drugs Gabapentin is not appreciably metabolized nor does it interfere with the metabolism of commonly coadministered antiepileptic drugs [see Clinical Pharmacology (12.3) ] . 7.3 Maalox ® (aluminum hydroxide, magnesium hydroxide) The mean bioavailability of gabapentin was reduced by about 20% with concomitant use of an antacid (Maalox ® ) containing magnesium and aluminum hydroxides. It is recommended that gabapentin be taken at least 2 hours following Maalox administration [see Clinical Pharmacology (12.3) ] . 7.4 Drug/Laboratory Test Interactions Because false positive readings were reported with the Ames N-Multistix SG ® dipstick test for urinary protein when gabapentin was added to other antiepileptic drugs, the more specific sulfosalicylic acid precipitation procedure is recommended to determine the presence of urine protein. Drug Interactions
• In Vitro Studies In vitro studies were conducted to investigate the potential of gabapentin to inhibit the major cytochrome P450 enzymes (CYP1A2, CYP2A6, CYP2C9, CYP2C19, CYP2D6, CYP2E1, and CYP3A4) that mediate drug and xenobiotic metabolism using isoform selective marker substrates and human liver microsomal preparations. Only at the highest concentration tested (171 mcg/mL; 1 mM) was a slight degree of inhibition (14% to 30%) of isoform CYP2A6 observed. No inhibition of any of the other isoforms tested was observed at gabapentin concentrations up to 171 mcg/mL (approximately 15 times the C max at 3600 mg/day).
• In Vivo Studies The drug interaction data described in this section were obtained from studies involving healthy adults and adult patients with epilepsy. Phenytoin In a single (400 mg) and multiple dose (400 mg three times a day) study of gabapentin in epileptic patients (N=8) maintained on phenytoin monotherapy for at least 2 months, gabapentin had no effect on the steady-state trough plasma concentrations of phenytoin and phenytoin had no effect on gabapentin pharmacokinetics. Carbamazepine Steady-state trough plasma carbamazepine and carbamazepine 10, 11 epoxide concentrations were not affected by concomitant gabapentin (400 mg three times a day; N=12) administration. Likewise, gabapentin pharmacokinetics were unaltered by carbamazepine administration. Valproic Acid The mean steady-state trough serum valproic acid concentrations prior to and during concomitant gabapentin administration (400 mg three times a day; N=17) were not different and neither were gabapentin pharmacokinetic parameters affected by valproic acid. Phenobarbital Estimates of steady-state pharmacokinetic parameters for phenobarbital or gabapentin (300 mg three times a day; N=12) are identical whether the drugs are administered alone or together. Naproxen Coadministration (N=18) of naproxen sodium capsules (250 mg) with gabapentin (125 mg) appears to increase the amount of gabapentin absorbed by 12% to 15%. Gabapentin had no effect on naproxen pharmacokinetic parameters. These doses are lower than the therapeutic doses for both drugs. The magnitude of interaction within the recommended dose ranges of either drug is not known. Hydrocodone Coadministration of gabapentin (125 to 500 mg; N=48) decreases hydrocodone (10 mg; N=50) C max and AUC values in a dose-dependent manner relative to administration of hydrocodone alone; C max and AUC values are 3% to 4% lower, respectively, after administration of 125 mg gabapentin and 21% to 22% lower, respectively, after administration of 500 mg gabapentin. The mechanism for this interaction is unknown. Hydrocodone increases gabapentin AUC values by 14%. The magnitude of interaction at other doses is not known. Morphine A literature article reported that when a 60 mg controlled-release morphine capsule was administered 2 hours prior to a 600 mg gabapentin capsule (N=12), mean gabapentin AUC increased by 44% compared to gabapentin administered without morphine. Morphine pharmacokinetic parameter values were not affected by administration of gabapentin 2 hours after morphine. The magnitude of interaction at other doses is not known. Cimetidine In the presence of cimetidine at 300 mg four times a day (N=12), the mean apparent oral clearance of gabapentin fell by 14% and creatinine clearance fell by 10%. Thus, cimetidine appeared to alter the renal excretion of both gabapentin and creatinine, an endogenous marker of renal function. This decrease in excretion of gabapentin by cimetidine is not expected to be of clinical importance. The effect of gabapentin on cimetidine was not evaluated. Oral Contraceptive Based on AUC and half-life, multiple-dose pharmacokinetic profiles of norethindrone and ethinyl estradiol following administration of tablets containing 2.5 mg of norethindrone acetate and 50 mcg of ethinyl estradiol were similar with and without coadministration of gabapentin (400 mg three times a day; N=13). The C max of norethindrone was 13% higher when it was coadministered with gabapentin; this interaction is not expected to be of clinical importance.
Use in specific populations
Pregnancy: Based on animal data, may cause fetal harm ( 8.1 ) 8.1 Pregnancy Pregnancy Exposure Registry There is a pregnancy exposure registry that monitors pregnancy outcomes in women exposed to antiepileptic drugs (AEDs), such as gabapentin, during pregnancy. Encourage women who are taking gabapentin during pregnancy to enroll in the North American Antiepileptic Drug (NAAED) Pregnancy Registry by calling the toll-free number 1-888-233-2334 or visiting http://www.aedpregnancyregistry.org/ . Risk Summary The totality of available data from published prospective and retrospective cohort studies pertaining to gabapentin use during pregnancy has not indicated an increased risk of major birth defects or miscarriage. There are important methodological limitations hindering interpretation of these studies [see Data ] . In nonclinical studies in mice, rats, and rabbits, gabapentin was developmentally toxic (increased fetal skeletal and visceral abnormalities, and increased embryofetal mortality) when administered to pregnant animals at doses similar to or lower than those used clinically [see Data ] . Postmarketing data suggest that extended gabapentin use with opioids close to delivery may increase the risk of neonatal withdrawal versus opioids alone [see Clinical Considerations ] . Although there is at least one report of neonatal withdrawal syndrome in an infant exposed to gabapentin alone during pregnancy, there are no comparative epidemiologic studies evaluating this association. Therefore, whether exposure to gabapentin alone late in pregnancy may cause withdrawal signs and symptoms is not known. The background risk of major birth defects and miscarriage for the indicated population is unknown. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2 to 4% and 15 to 20%, respectively. Clinical Considerations Fetal/Neonatal Adverse Reactions Neonatal withdrawal syndrome has been reported in newborns exposed to gabapentin in utero for an extended period of time when also exposed to opioids close to delivery. Neonatal withdrawal signs and symptoms reported have included tachypnea, vomiting, diarrhea, hypertonia, irritability, sneezing, poor feeding, hyperactivity, abnormal sleep pattern, and tremor. Reported signs and symptoms that may also be related to withdrawal include tongue thrusting, wandering eye movements while awake, back arching, and continuous extremity movements. Observe neonates exposed to gabapentin and opioids for signs and symptoms of neonatal withdrawal and manage accordingly. Data Human Data An observational study based on routinely collected data from administrative and medical registers in Denmark, Finland, Norway, and Sweden, compared the prevalence of major congenital malformations in approximately 1,500 pregnancies exposed to gabapentin monotherapy in the first trimester to pregnancies unexposed to antiepileptics (n=2,995,816) and pregnancies exposed to lamotrigine monotherapy in the first trimester (n=7,582). The adjusted prevalence ratios in a pooled analysis were 1.00 (95% CI: 0.80-1.24) compared to pregnancies unexposed to antiepileptics and 1.29 (95% CI: 1.00-1.67) compared to pregnancies exposed to lamotrigine monotherapy in the first trimester. Data from another observational study in the US based on Medicaid data, which compared the risk for major congenital malformations in more than 4,600 pregnancies exposed to gabapentin during the first trimester to unexposed pregnancies (n=1,753,865), estimated an adjusted relative risk of 1.07 (95% CI: 0.94-1.21). Data from a cohort study of over 200,000 Medicaid-eligible pregnancies with prescription opioid exposure in the last 45 days of pregnancy found that the risk of neonatal drug withdrawal was greater in pregnancies with combined exposure to gabapentin and opioids compared to pregnancies with exposure to opioids alone. The data from these observational studies should be interpreted with caution due to the potential for exposure misclassification, outcome misclassification, and residual confounding, including by underlying disease. Animal Data When pregnant mice received oral doses of gabapentin (500, 1000, or 3000 mg/kg/day) during the period of organogenesis, embryofetal toxicity (increased incidences of skeletal variations) was observed at the two highest doses. The no-effect dose for embryofetal developmental toxicity in mice (500 mg/kg/day) is less than the maximum recommended human dose (MRHD) of 3600 mg on a body surface area (mg/m 2 ) basis. In studies in which rats received oral doses of gabapentin (500 to 2000 mg/kg/day) during pregnancy, adverse effect on offspring development (increased incidences of hydroureter and/or hydronephrosis) were observed at all doses. The lowest dose tested is similar to the MRHD on a mg/m 2 basis. When pregnant rabbits were treated with gabapentin during the period of organogenesis, an increase in embryofetal mortality was observed at all doses tested (60, 300, or 1500 mg/kg). The lowest dose tested is less than the MRHD on a mg/m 2 basis. In a published study, gabapentin (400 mg/kg/day) was administered by intraperitoneal injection to neonatal mice during the first postnatal week, a period of synaptogenesis in rodents (corresponding to the last trimester of pregnancy in humans). Gabapentin caused a marked decrease in neuronal synapse formation in brains of intact mice and abnormal neuronal synapse formation in a mouse model of synaptic repair. Gabapentin has been shown in vitro to interfere with activity of the α2δ subunit of voltage-activated calcium channels, a receptor involved in neuronal synaptogenesis. The clinical significance of these findings is unknown. 8.2 Lactation Risk Summary Gabapentin is secreted in human milk following oral administration.
Pregnancy
8.1 Pregnancy Pregnancy Exposure Registry There is a pregnancy exposure registry that monitors pregnancy outcomes in women exposed to antiepileptic drugs (AEDs), such as gabapentin, during pregnancy. Encourage women who are taking gabapentin during pregnancy to enroll in the North American Antiepileptic Drug (NAAED) Pregnancy Registry by calling the toll-free number 1-888-233-2334 or visiting http://www.aedpregnancyregistry.org/ . Risk Summary The totality of available data from published prospective and retrospective cohort studies pertaining to gabapentin use during pregnancy has not indicated an increased risk of major birth defects or miscarriage. There are important methodological limitations hindering interpretation of these studies [see Data ] . In nonclinical studies in mice, rats, and rabbits, gabapentin was developmentally toxic (increased fetal skeletal and visceral abnormalities, and increased embryofetal mortality) when administered to pregnant animals at doses similar to or lower than those used clinically [see Data ] . Postmarketing data suggest that extended gabapentin use with opioids close to delivery may increase the risk of neonatal withdrawal versus opioids alone [see Clinical Considerations ] . Although there is at least one report of neonatal withdrawal syndrome in an infant exposed to gabapentin alone during pregnancy, there are no comparative epidemiologic studies evaluating this association. Therefore, whether exposure to gabapentin alone late in pregnancy may cause withdrawal signs and symptoms is not known. The background risk of major birth defects and miscarriage for the indicated population is unknown. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2 to 4% and 15 to 20%, respectively. Clinical Considerations Fetal/Neonatal Adverse Reactions Neonatal withdrawal syndrome has been reported in newborns exposed to gabapentin in utero for an extended period of time when also exposed to opioids close to delivery. Neonatal withdrawal signs and symptoms reported have included tachypnea, vomiting, diarrhea, hypertonia, irritability, sneezing, poor feeding, hyperactivity, abnormal sleep pattern, and tremor. Reported signs and symptoms that may also be related to withdrawal include tongue thrusting, wandering eye movements while awake, back arching, and continuous extremity movements. Observe neonates exposed to gabapentin and opioids for signs and symptoms of neonatal withdrawal and manage accordingly. Data Human Data An observational study based on routinely collected data from administrative and medical registers in Denmark, Finland, Norway, and Sweden, compared the prevalence of major congenital malformations in approximately 1,500 pregnancies exposed to gabapentin monotherapy in the first trimester to pregnancies unexposed to antiepileptics (n=2,995,816) and pregnancies exposed to lamotrigine monotherapy in the first trimester (n=7,582). The adjusted prevalence ratios in a pooled analysis were 1.00 (95% CI: 0.80-1.24) compared to pregnancies unexposed to antiepileptics and 1.29 (95% CI: 1.00-1.67) compared to pregnancies exposed to lamotrigine monotherapy in the first trimester. Data from another observational study in the US based on Medicaid data, which compared the risk for major congenital malformations in more than 4,600 pregnancies exposed to gabapentin during the first trimester to unexposed pregnancies (n=1,753,865), estimated an adjusted relative risk of 1.07 (95% CI: 0.94-1.21). Data from a cohort study of over 200,000 Medicaid-eligible pregnancies with prescription opioid exposure in the last 45 days of pregnancy found that the risk of neonatal drug withdrawal was greater in pregnancies with combined exposure to gabapentin and opioids compared to pregnancies with exposure to opioids alone. The data from these observational studies should be interpreted with caution due to the potential for exposure misclassification, outcome misclassification, and residual confounding, including by underlying disease. Animal Data When pregnant mice received oral doses of gabapentin (500, 1000, or 3000 mg/kg/day) during the period of organogenesis, embryofetal toxicity (increased incidences of skeletal variations) was observed at the two highest doses. The no-effect dose for embryofetal developmental toxicity in mice (500 mg/kg/day) is less than the maximum recommended human dose (MRHD) of 3600 mg on a body surface area (mg/m 2 ) basis. In studies in which rats received oral doses of gabapentin (500 to 2000 mg/kg/day) during pregnancy, adverse effect on offspring development (increased incidences of hydroureter and/or hydronephrosis) were observed at all doses. The lowest dose tested is similar to the MRHD on a mg/m 2 basis. When pregnant rabbits were treated with gabapentin during the period of organogenesis, an increase in embryofetal mortality was observed at all doses tested (60, 300, or 1500 mg/kg). The lowest dose tested is less than the MRHD on a mg/m 2 basis. In a published study, gabapentin (400 mg/kg/day) was administered by intraperitoneal injection to neonatal mice during the first postnatal week, a period of synaptogenesis in rodents (corresponding to the last trimester of pregnancy in humans). Gabapentin caused a marked decrease in neuronal synapse formation in brains of intact mice and abnormal neuronal synapse formation in a mouse model of synaptic repair. Gabapentin has been shown in vitro to interfere with activity of the α2δ subunit of voltage-activated calcium channels, a receptor involved in neuronal synaptogenesis. The clinical significance of these findings is unknown.
Pediatric use
8.4 Pediatric Use Safety and effectiveness of gabapentin in the management of postherpetic neuralgia in pediatric patients have not been established. Safety and effectiveness as adjunctive therapy in the treatment of partial seizures in pediatric patients below the age of 3 years has not been established [see Clinical Studies (14.2) ] .
Geriatric use
8.5 Geriatric Use The total number of patients treated with gabapentin in controlled clinical trials in patients with postherpetic neuralgia was 336, of which 102 (30%) were 65 to 74 years of age, and 168 (50%) were 75 years of age and older. There was a larger treatment effect in patients 75 years of age and older compared to younger patients who received the same dosage. Since gabapentin is almost exclusively eliminated by renal excretion, the larger treatment effect observed in patients ≥75 years may be a consequence of increased gabapentin exposure for a given dose that results from an age-related decrease in renal function. However, other factors cannot be excluded. The types and incidence of adverse reactions were similar across age groups except for peripheral edema and ataxia, which tended to increase in incidence with age. Clinical studies of gabapentin in epilepsy did not include sufficient numbers of subjects aged 65 and over to determine whether they responded differently from younger subjects. Other reported clinical experience has not identified differences in responses between the elderly and younger patients. In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range, reflecting the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy. This drug is known to be substantially excreted by the kidney, and the risk of toxic reactions to this drug may be greater in patients with impaired renal function. Because elderly patients are more likely to have decreased renal function, care should be taken in dose selection, and dose should be adjusted based on creatinine clearance values in these patients [see Dosage and Administration (2.4) , Adverse Reactions (6) , and Clinical Pharmacology (12.3) ] .
Overdosage
Signs of acute toxicity in animals included ataxia, labored breathing, ptosis, sedation, hypoactivity, or excitation. Acute oral overdoses of gabapentin have been reported. Symptoms have included double vision, tremor, slurred speech, drowsiness, altered mental status, dizziness, lethargy, and diarrhea. Fatal respiratory depression has been reported with gabapentin overdose, alone and in combination with other CNS depressants. Gabapentin can be removed by hemodialysis. If overexposure occurs, call your poison control center at 1-800-222-1222.
Description
The active ingredient in gabapentin oral solution is gabapentin, which has the chemical name 1-(aminomethyl)cyclohexaneacetic acid. The molecular formula of gabapentin is C 9 H 17 NO 2 and the molecular weight is 171.24. The structural formula of gabapentin is: Gabapentin is a white to off-white crystalline solid with a pK a1 of 3.7 and a pK a2 of 10.7. It is freely soluble in water and both basic and acidic aqueous solutions. The log of the partition coefficient (n-octanol/0.05M phosphate buffer) at pH 7.4 is -1.25. Gabapentin oral solution contains 250 mg of gabapentin per 5 mL (50 mg per mL) and the following inactive ingredients: artificial cool strawberry anise flavor, glycerin, purified water, and xylitol. Gabapentin Structural Formula
Mechanism of action
12.1 Mechanism of Action The precise mechanisms by which gabapentin produces its analgesic and antiepileptic actions are unknown. Gabapentin is structurally related to the neurotransmitter gamma-aminobutyric acid (GABA) but has no effect on GABA binding, uptake, or degradation. In vitro studies have shown that gabapentin binds with high-affinity to the α2δ subunit of voltage-activated calcium channels; however, the relationship of this binding to the therapeutic effects of gabapentin is unknown.
How supplied
Gabapentin Oral Solution is supplied as follows: 250 mg per 5 mL oral solution: Clear colorless to slightly yellow solution; each 5 mL of oral solution contains 250 mg of gabapentin; available in: Bottles containing 470 mL: NDC 59762-5050-7 Store gabapentin oral solution refrigerated, 2°C to 8°C (36°F to 46°F).
Patient information
Advise the patient to read the FDA-approved patient labeling (Medication Guide). Administration Information Inform patients that gabapentin is taken orally with or without food. Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS)/Multiorgan Hypersensitivity Prior to initiation of treatment with gabapentin, instruct patients that a rash or other signs or symptoms of hypersensitivity (such as fever or lymphadenopathy) may herald a serious medical event and that the patient should report any such occurrence to a healthcare provider immediately [see Warnings and Precautions (5.1) ] . Anaphylaxis and Angioedema Advise patients to discontinue gabapentin and seek medical care if they develop signs or symptoms of anaphylaxis or angioedema [see Warnings and Precautions (5.2) ] . Dizziness and Somnolence and Effects on Driving and Operating Heavy Machinery Advise patients that gabapentin may cause dizziness, somnolence, and other symptoms and signs of CNS depression. Other drugs with sedative properties may increase these symptoms. Accordingly, although patients’ ability to determine their level of impairment can be unreliable, advise them neither to drive a car nor to operate other complex machinery until they have gained sufficient experience on gabapentin to gauge whether or not it affects their mental and/or motor performance adversely. Inform patients that it is not known how long this effect lasts [see Warnings and Precautions (5.3) and Warnings and Precautions (5.4) ] . Suicidal Thinking and Behavior Counsel the patient, their caregivers, and families that AEDs, including gabapentin, may increase the risk of suicidal thoughts and behavior. Advise patients of the need to be alert for the emergence or worsening of symptoms of depression, any unusual changes in mood or behavior, or the emergence of suicidal thoughts, behavior, or thoughts about self-harm. Instruct patients to report behaviors of concern immediately to healthcare providers [see Warnings and Precautions (5.5) ] . Also, inform patients who plan to or have discontinued gabapentin that suicidal thoughts and behavior can appear even after the drug is stopped. Respiratory Depression Inform patients about the risk of respiratory depression. Include information that the risk is greatest for those using concomitant CNS depressants (such as opioid analgesics) or those with underlying respiratory impairment. Teach patients how to recognize respiratory depression and advise them to seek medical attention immediately if it occurs [see Warnings and Precautions (5.8) ] . Use in Pregnancy Instruct patients to notify their healthcare provider if they are pregnant or intend to become pregnant during therapy, and to notify their healthcare provider if they are breast feeding or intend to breast feed during therapy [see Use in Specific Populations (8.1) and (8.2) ] . Encourage patients to enroll in the NAAED Pregnancy Registry if they become pregnant. This registry is collecting information about the safety of antiepileptic drugs during pregnancy. To enroll, patients can call the toll-free number 1-888-233-2334 [see Use in Specific Populations (8.1) ] . GREENSTONE ® BRAND Distributed by: Greenstone LLC Morgantown, WV 26505 U.S.A. © 2025 Viatris Inc. The brands listed are trademarks of their respective owners. GST:GABA:R2
Label text from the FDA structured product label by Mylan Pharmaceuticals Inc. (revised Apr 12, 2025). Long sections are shortened; the complete label is on DailyMed.
Active ingredients
- Gabapentin in 562 products
Gabapentin NDC products (562)
Gabapentin recalls
- D-0030-2026 Oct 29, 2025 · Class II · Ongoing
Failed Impurities/Degradation Specifications: an out of specification result obtained during routine stability testing for Highest Unknown Impurity . - D-0031-2026 Oct 29, 2025 · Class II · Ongoing
Failed Impurities/Degradation Specifications: an out of specification result obtained during routine stability testing for Highest Unknown Impurity . - D-0507-2025 Jul 9, 2025 · Class II · Ongoing
Defective container; blister packaging inadequately sealed. - D-0508-2025 Jul 9, 2025 · Class II · Ongoing
Defective container; blister packaging inadequately sealed. - D-0311-2025 Apr 16, 2025 · Class III · Ongoing
Cross Contamination - D-0312-2025 Apr 16, 2025 · Class III · Ongoing
Cross Contamination - D-0320-2025 Apr 16, 2025 · Class II · Ongoing
CGMP Deviations - D-0634-2024 Aug 14, 2024 · Class II · Terminated
Presence of Foreign Tablets; 3 fused tablets of Metformin ER 500 mg were found in bottle of Gabapentin Tablets - D-0570-2023 May 17, 2023 · Class III · Terminated
Product mixup: one foreign tablet found in product. - D-0354-2023 Mar 8, 2023 · Class III · Terminated
Presence of Foreign Tablets/Capsules: Pharmacist reported presence of some Gabapentin tablets 800 mg comingled in Gabapentin 600 mg 500 count bottles. - D-1272-2020 May 27, 2020 · Class III · Terminated
Failed Impurities/Degradation Specifications; failure of Impurity A test at the 12-month long-term stability testing. - D-1232-2020 Apr 22, 2020 · Class II · Terminated
CGMP Deviations: Products were manufactured in a processing area in which water leakage was observed - D-0330-2015 Jan 14, 2015 · Class II · Terminated
Failed Tablet/Capsule Specifications: Complaints of empty capsules received. - D-0336-2015 Jan 14, 2015 · Class II · Terminated
Failed Capsule/Tablet Specifications: Actavis has received several complaint for clumping and breaking of capsules with some bottles showing popped out bottle bottom (round bottom) and creased labels from one… - D-0338-2015 Jan 14, 2015 · Class II · Terminated
Failed Capsule/Tablet Specifications: Actavis has received several complaint for clumping and breaking of capsules with some bottles showing popped out bottle bottom (round bottom) and creased labels from one… - D-329-2013 May 22, 2013 · Class III · Terminated
Chemical Contamination: Gabapentin Sodium tablets is recalled due to complaints related to an off - odor described as moldy, musty or fishy in nature.
Frequently asked questions
What is Gabapentin used for?
Gabapentin is indicated for: • Management of postherpetic neuralgia in adults • Adjunctive therapy in the treatment of partial onset seizures, with and without secondary generalization, in adults and pediatric patients 3 years and older with epilepsy Gabapentin is indicated for: • Postherpetic neuralgia in adults ( 1 ) • Adjunctive therapy in the treatment of partial onset seizures, with and…
What are the side effects of Gabapentin?
The following serious adverse reactions are discussed in greater detail in other sections: • Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS)/Multiorgan Hypersensitivity [see Warnings and Precautions (5.1) ] • Anaphylaxis and Angioedema [see Warnings and Precautions (5.2) ] • Somnolence/Sedation and Dizziness [see Warnings and Precautions (5.4) ] • Suicidal Behavior and Ideation [see… See the full label for the complete list.
Who makes Gabapentin?
Gabapentin is listed by 40 labelers in the FDA NDC directory, including A-S Medication Solutions, Acella Pharmaceuticals, LLC, Actavis Pharma, Inc., Advagen Pharma Ltd.
Has Gabapentin been recalled?
The FDA enforcement database lists 16 recalls for Gabapentin, most recently D-0030-2026 (class ii): Failed Impurities/Degradation Specifications: an out of specification result obtained during routine stability testing for Highest Unknown Impurity .