Prescription Drug Information: Gabapentin
GABAPENTIN- gabapentin capsule
1 INDICATIONS AND USAGE
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
2 DOSAGE AND ADMINISTRATION
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 1,800 mg/day (600 mg three times a day). In clinical studies, efficacy was demonstrated over a range of doses from 1,800 mg/day to 3,600 mg/day with comparable effects across the dose range; however, in these clinical studies, the additional benefit of using doses greater than 1,800 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 2,400 mg/day have been well tolerated in long-term clinical studies. Doses of 3,600 mg/day have also been administered to a small number of patients for a relatively short duration, and have been well tolerated. Administer gabapentin three times a day using 300 mg or 400 mg capsules. 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 well tolerated 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):
|Renal Function Creatinine Clearance (mL/min)||Total Daily Dose Range (mg/day)||Dosage Regimen (mg)|
|TID = Three times a day; BID = Two times a day; QD = Single daily dose|
|≥ 60||900 to 3,600||300 TID||400 TID||600 TID||800 TID||1,200 TID|
|> 30 to 59||400 to 1,400||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 *||100 to 300||100 QD||125 QD||150 QD||200 QD||300 QD|
|Post-Hemodialysis Supplemental Dose (mg) †|
|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:
|CLCr =||[140 − age (years) ] × weight (kg)||( × 0.85 for female patients)|
|72 × serum creatinine (mg/dL)|
The use of gabapentin in patients less than 12 years of age with compromised renal function has not been studied.
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.
Gabapentin capsules should be swallowed whole with water.
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).
3 DOSAGE FORMS AND STRENGTHS
- 100 mg: Capsules, with grey “100 mg” imprinted on the white body and grey “OE B56” on the white cap. The content is white or off-white powder.
- 300 mg: Capsules, with grey “300 mg” imprinted on the white body and grey “OE B57” on the yellow cap. The content is white or off-white powder.
- 400 mg: Capsules, with grey “400 mg” imprinted on the white body and grey “OE B58” on the orange cap. The content is white or off-white powder.
Gabapentin is contraindicated in patients who have demonstrated hypersensitivity to the drug or its ingredients.
5 WARNINGS AND PRECAUTIONS
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 1,800 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 3,600 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)] .
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