The initial oral dose of gabapentin for the treatment of epilepsy is 300 mg on the first day of treatment, 300 mg twice daily on the second day, and 300 mg three times daily on the third day; thereafter the dose may be increased in increments of 300 mg every 2 to 3 days until effective antiepileptic control is achieved, which is usually within the range of 0.9 to 3.6 g daily. Higher doses up to a maximum of 4.8 g daily have been reported to be well tolerated. The total daily dose should be taken in three equally divided doses and the maximum dosage interval should not exceed 12 hours. In the treatment of neuropathic pain, doses should be titrated to a usual maximum of 1.8 g daily in three divided doses, in a similar manner to that recommended above for the treatment of epilepsy. Higher doses have sometimes been given.
Administration in children: For the treatment of partial seizures with or without secondary generalization, gabapentin is licensed for use as adjunctive therapy in children aged 6 years and over and as monotherapy in those aged 12 years and over. As adjunctive therapy, gabapentin may be given in an initial oral dose of 10 to 15 mg/kg daily, titrated over a period of about 3 days until effective antiepileptic control is achieved, which is usually within the range 25 to 35 mg/kg daily. Higher doses up to a maximum of 50 mg/kg daily have been reported to be well tolerated. Although not licensed for use in younger children, the BNFC suggests that similar initial doses may be used in those aged 2 to 12 years; maintenance doses of 10 to 20 mg/kg 3 times daily (up to 900 mg daily for children weighing 36 kg or under, or 1.2 g daily for those over 36 kg) are also recommended. Older children may be given the usual adult dosage regimen (see previously) titrated to a maximum of 2.4 g daily. When used as monotherapy, the usual adult dosage regimen is given.
Administration in renal impairment: Reduced doses of gabapentin are recommended for patients with renal impairment or those undergoing haemodialysis. Licensed UK product information recommends the following maintenance doses based on creatinine clearance (CC) and given as 3 divided doses: CC 50 to 79 mL/minute: 600 to 1800 mg daily.
CC 30 to 49 mL/minute: 300 to 900 mg daily.
CC 15 to 29 mL/minute: 300 mg on alternate days to 600 mg daily.
CC less than 15 mL/minute: 300 mg on alternate days to 300 mg daily.
For those undergoing haemodialysis who have never received gabapentin, the recommended loading dose is 300 to 400 mg followed by 200 to 300 mg after each 4 hours of haemodialysis. On dialysis-free days no doses of gabapentin should be given.