LAMOTRIGINE IN ABSENCE AND PRIMARY GENERALIZED EPILEPSIES

Although lamotrigine has been approved in the United States as adjunct ive therapy for partial seizures in patients older than 12 years, ther e is increasing evidence that it is just as effective, if not more eff ective, in the treatment of generalized seizures. A large number of op en-label studies and some single-blind data, all using lamotrigine as add-on therapy in patients with previously refractory generalized seiz ures, are available. Controlled studies, some on newly diagnosed, prev iously untreated patients with generalized seizures are ongoing. Inves tigations have demonstrated that patients with the following generaliz ed seizure types improve with lamotrigine add-on therapy: Typical and atypical absence, atonic, generalized tonic-clonic, myoclonic, and clo nic seizures. Response rates, defined as the percentage of patients wi th better than 50% reduction in seizure frequency, have been, dependin g on seizure type, in the range of 30% to 56%, with 0 to 33% of the pa tients becoming seizure free. The best responses have been noted in ty pical and atypical absences, and atonic seizures. Children and adults appear to have comparable responses. In addition, add-on studies in pa tients with specific, previously refractory, epilepsy syndromes have d emonstrated that the best improvement in seizure control occurs in pat ients with petit mal epilepsy, ''other symptomatic'' generalized epile psies, and in Lennox-Gastaut syndrome, followed by patients with other myoclonic epilepsies, myoclonic absence and West syndrome. Many previ ously refractory patients are able to achieve lamotrigine monotherapy. However, patients with nonprogressive myoclonic epilepsy have little, if any, response. Early data from ambulatory encephalographic (EEG) r ecordings in patients with previously refractory absence seizures, and hom controlled studies on patients with newly diagnosed typical absen ce seizures, appear to confirm the efficacy of lamotrigine in those pa tients. Controlled studies are ongoing in patients with absence seizur es, in patients with generalized tonic-clonic seizures, and in patient s with Lennox-Gastaut syndrome. Dosing in generalized seizures is simi lar to that for partial seizures. Because of the shorter half-life of lamotrigine in children, as compared to adults, higher (mg/kg) doses a re often needed in young patients. We conclude that lamotrigine is a p romising drug for absence and primary generalized seizures in both chi ldren and adults.