Evaluation of gabapentin in an outpatient and office-based sample of epilepsy patients

A retrospective analysis of charts of patients who received gabapentin (GBP) as adjunctive anticonvulsant therapy in its first year of marketing, between March 1994 and April 1995 was conducted to evaluate patterns of use, side effects, and efficacy in the general epilepsy population. Ninety patients (45 men, 45 women) with an average age of 33.5 years (range: 7 months-78 years) were included. Average GBP dosage was 1700 mg/day; 46 patients took <1800 mg, and 44 patients took ≤1800 mg/day. Duration of GBP treatment ranged from 1 month-14 months. Patients took an average of 1.7 concurrent antiepileptic drugs while on GBP. A total of 13 patients were on GBP monotherapy, four at the outset joined by nine others during the study. Gabapentin was associated with improvement as assessed by reduction of seizure frequency in 69 patients (77%). Sixty patients (67%) who reported no side effects had a mean GBP dosage of 1900 mg/day (median: 2000 mg/day). The 30 patients who experienced side effects had a mean GBP dosage of 1600 mg/day (median: 1500 mg/day). Gabapentin was discontinued in 21 patients, six because of side effects, nine because of lack of efficacy, and six because of a combination of both. Gabapentin was used in more difficult patients with intractable epilepsy and was generally well tolerated. Higher doses were not associated with more side effects, suggesting that GBP-related side effects may not be dose-related.