Gabapentin capsules are given orally with or without food.
Gabapentin capsules should be swallowed whole with plenty of water.
If 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).
2.1 Postherpetic Neuralgia
In adults with postherpetic neuralgia, gabapentin therapy 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 Epilepsy with Partial Onset Seizures
Gabapentin is recommended for add-on therapy in patients 3 years of age and older. Effectiveness in pediatric patients below the age of 3 years has not been established.
Patients 12 years of age and above: The starting dose is 300 mg three times a day. The effective dose of gabapentin is 300 mg to 600 mg three times a day. Dosages up to 2400 mg/day have been well tolerated 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, and have been well tolerated. Gabapentin should be administered 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 effective dose reached by upward titration over a period of approximately 3 days. The effective dose of gabapentin in patients 3 to 4 years of age is 40 mg/kg/day, given in three divided doses. The effective 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. 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.
It is not necessary to monitor gabapentin plasma concentrations to optimize gabapentin therapy. Further, because there are no significant pharmacokinetic interactions among gabapentin and other commonly used antiepileptic drugs, the addition of gabapentin does not alter the plasma levels of these drugs appreciably.
If gabapentin is discontinued and/or an alternate anticonvulsant medication is added to the therapy, this should be done gradually over a minimum of 1 week.
2.3 Patients with Renal Impairment
Dosage adjustment in patients 12 years of age and older with compromised renal function 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
a 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).
b 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.
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
15a
100 to 300
100 QD
125 QD
150 QD
200 QD
300 QD
Post-Hemodialysis Supplemental Dose (mg)b
Hemodialysis
125b
150b
200b
250b
350b
TID = Three times a day; BID = Two times a day; QD = Single daily dose
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.
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.
