Vigabatrin: A novel therapy for seizure disorders

OBJECTIVE: To review the pharmacology, pharmacokinetics, efficacy, and adve rse effects of vigabatrin and its role in the management of seizure disorde rs. METHODS: A MEDLINE search of English-language literature from January 1993 through January 1999 was conducted using vigabatrin as a search term to ide ntify pertinent studies and review articles. Additional studies were identi fied from the bibliographies of reviewed literature. The manufacturer provi ded postmarketing surveillance data. Priority was given to randomized, doub le-blind, placebo-controlled studies. FINDINGS: Vigabatrin is a selective and irreversible inhibitor of gamma-ami nobutyric acid transaminase. In controlled clinical trials of vigabatrin ad d-on therapy in patients with uncontrolled partial seizures, 24-67% of pati ents achieved a less than or equal to 50% reduction in seizure frequency. D ata from two comparative trials with carbamazepine monotherapy indicate tha t vigabatrin monotherapy reduces the frequency of partial seizures in patie nts with newly diagnosed epilepsy. Vigabatrin also controls infantile spasm s, particularly those associated with tuberous sclerosis. Vigabatrin is mor e effective in patients with partial seizures than in those with generalize d seizures. The drug is generally well tolerated. Headache and drowsiness w ere the most common adverse effects observed in controlled clinical trials; visual field defects, psychiatric reactions, and hyperactivity also have b een reported. There are no known clinically significant drug interactions. CONCLUSIONS: Vigabatrin improves seizure control as add-on therapy for refr actory partial seizures and may produce therapeutic benefits in the treatme nt of infantile spasms. Vigabatrin is generally well tolerated, with a conv enient administration schedule, a lack of known significant drug interactio ns, and no need for routine monitoring of plasma concentrations.