GABAPENTIN AS ADD-ON THERAPY FOR REFRACTORY PARTIAL EPILEPSY - RESULTS OF 5 PLACEBO-CONTROLLED TRIALS

Gabapentin (GBP, Neurontin), a new antiepileptic drug (AED) with a nov el mechanism of action, exhibits low acute toxicity in mice, rats, and monkeys, and is not teratogenic. GBP pharmacokinetics are simple and predictable; GBP is eliminated by urinary excretion, is not protein bo und or metabolized, does not induce or inhibit hepatic enzymes, and do es not interact with other AEDs. In five placebo-controlled, double-bl ind studies of GBP as add-on therapy, 307 patients with refractory par tial seizures received placebo and 485 received GBP dosages of 600, 90 0, 1,200, or 1,800 mg/day for 12 weeks following a 12-week baseline. S eizure frequency, as measured by response ratio and responder rate, wa s improved for patients receiving GBP compared with placebo: differenc es were statistically significant in two of the three large, multicent er studies. Adverse events occurred in 76% of GBP-treated patients, co mpared with 57% of placebo-treated patients. No serious adverse events were consistently attributable to GBP therapy. Changes in clinical la boratory values were not considered clinically important. GBP represen ts a significant addition to the armamentarium of AEDs available for t reatment of patients with epilepsy.