[Changing lamotrigine preparations in epilepsy patients. Experiences of a university epilepsy outpatient centre].

An increasing number of second-generation antiepileptic drugs have become available as generics. There is an ongoing debate as to whether this opens up ways to save costs or if efficacy and tolerability of an established treatment are at stake. We here present a retrospective analysis of outpatients treated with lamotrigine regarding the frequency of treatment switches and its effects on seizure control and tolerability. In 13 of 285 patients under treatment with lamotrigine the prescribed drug was changed; in 6 of these seizure relapse occurred after a period of 3 months to 6 years of seizure freedom and 3 patients experienced new side effects. Compared to matched controls, the risk for loss of seizure control was significantly elevated by a factor of 17; adverse events were three times more frequent (n.s.). Consecutive determinations of serum levels suggest that these problems were related to changes in the pharmacokinetics of different formulations. Frequent problems related to a switch of medication are discussed under medical and socio-economic aspects.