Main Entry Criteria. Patients ≥12 years with medication-resistant partial seizures on one to two standard antiepileptic drugs (AEDs)

Comparator. Add-on gabapentin 900 mg/day, 1,200 mg/day, or placebo

Number of Patients. 272

Primary Outcome Variable; Important Secondary Variables. Median percentage seizure reduction; 50% responder rate, response ratio

Results. The responder rates and response ratios were significantly better in both the 900-mg/day and 1,200 mg/day groups compared with placebo.

Main Entry Criteria. Patients >13 years with medication-resistant partial seizures on one to two standard AEDs

Comparator. Add-on gabapentin 1,200 mg/day compared with placebo

Number of Patients. 127

Primary Outcome Variable; Important Secondary Variables. Median percentage seizure reduction; 50% responder rate, response ratio

Results. The responder rates and response ratios were significantly better in the 1,200 mg/day group compared with placebo.

Main Entry Criteria. Patients ≥16 years with medication-resistant partial seizures on one to two standard AEDs

Comparator. Add-on gabapentin 600, 1,200, or 1,800 mg/day compared with placebo

Number of Patients. 306

Primary Outcome Variable; Important Secondary Variables. Median percentage seizure reduction, 50% responder rate, response ratio

Results. The response ratios were significantly better in all gabapentin treatment groups compared with placebo; the 50% responder rate was significantly better in the 1,800 mg/day gabapentin group compared with placebo.

Main Entry Criteria. Patients ≥16 years with medication-resistant partial seizures on one to two standard AEDs

Comparator. Add-on gabapentin 900 or 1,200 mg/day compared with placebo

Number of Patients. 43

Primary Outcome Variable. Change in seizure frequency compared with baseline

Results. A statistically significant decrease in seizure frequency was seen in the gabapentin 1,200 mg/day group compared with placebo; no difference was seen between the gabapentin 900 mg/day group and placebo.

Main Entry Criteria. Patients ≥12 years who have refractory generalized seizures (idiopathic or symptomatic) on one to two standard AEDs

Comparator. Add-on gabapentin 1,200 mg/day versus placebo

Number of Patients. 129

Primary Outcome Variable; Important Secondary Variables. 50% responder rate, percentage change in seizure frequency, and response ratio for generalized tonic-clonic (GTC) seizures; other types of generalized seizures were of secondary interest

Results. There was no significant difference between the gabapentin group and placebo group in any of the outcome variables; a nonsignificant trend in 50% responder rate and response ratio in GTC seizures favored gabapentin; absence seizures and myoclonic seizures did not respond to gabapentin.

Main Entry Criteria. Patients ≥18 years who have refractory partial or generalized seizures (idiopathic or symptomatic) on one to two standard AEDs

Comparator. Add-on gabapentin 300 mg/day versus gabapentin 600 mg/day versus 900 mg/day

Number of Patients. 21

Primary Outcome Variable. Percentage change in seizure frequency

Results. Percentage change in seizure frequency from baseline was significant in the 900 mg/day group. The percentage change in seizure frequency was significantly better in the 900 mg/day group compared with the 300 mg/day and the 600 mg/day group.

Main Entry Criteria. Patients >12 years with medication-resistant partial seizures on one to two standard AEDs

Comparator. Baseline compared with gabapentin ≤1,800 mg/day and >1,800 mg/day (dose was titrated to efficacy up to 3,600 mg/day)

Primary Outcome Variable; Important Secondary Variables. Number and percentage change in total seizures, seizure-free rate, 50% responder rate

Number of Patients. 1,055

Results. 61% average percentage seizure reduction; the 50% responder rate was 76% overall; to achieve seizure freedom, 33.4% (352/1,055) required dose ≤1,800 mg/day, 28.4% required dose >1,800 mg/day, and 46.4% taking any dose up to 3,600 mg/day were seizure free; safe and well tolerated in both groups.

Main Entry Criteria. Patients 3 to 12 years with medication-resistant partial seizures on one to three standard AEDs

Comparator. Add-on gabapentin 23.2 to 35.3 mg/kg/day (600 to 1,800 mg/day according to weight) compared with placebo

Primary Outcome Variable; Important Secondary Variables. Median percentage seizure reduction; 50% responder rate, response ratio

Number of Patients. 247

Results. Response ratio was significantly better for gabapentin-treated patients than for placebo. Nonsignificant trends in 50% responder rates and percentage seizure reduction favored gabapentin.

Main Entry Criteria. Patients ≥16 years with newly diagnosed epilepsy with partial seizures with or without secondary generalization or with primary generalized seizures

Comparator. Gabapentin 1,800 mg/day versus lamotrigine 150 mg/day

Primary Outcome Variable; Important Secondary Variables. Time to exit because of lack of efficacy at highest tolerated dose, addition of second AED, or occurrence of intolerable adverse effects; percentage of completers; percentage seizure free; withdrawal rate for adverse effects

Number of Patients. 291

Results. Similar rates of tolerability and efficacy for two drugs in all seizure types were studied.

Main Entry Criteria. Patients ≥16 years with newly diagnosed epilepsy with partial seizures with or without secondary generalization

Comparator. Masked gabapentin 300 mg/day, 900 mg/day, or 1,800 mg/day versus open-label carbamazepine

Number of Patients. 292

Primary Outcome Variable; Important Secondary Variables. Time to exit because of three partial seizures or one GTC seizure, addition of second AED, or occurrence of intolerable adverse effects

Results. Longer time to exit for gabapentin 900 mg/day and 1,800 mg/day compared with 300 mg/day; exit rates (exit because of adverse effects or lack of efficacy) were similar for carbamazepine and 1,800 mg/day gabapentin (54% and 57%, respectively) but better for gabapentin 900 mg/day (44%); more patients on carbamazepine exited the study because of adverse effects and more patients on gabapentin exited because of lack of efficacy.