Abstracts

Rationale: About 10 years after the first registration of an oxcarbazepine product, the “old” Trileptal formulation, in Denmark in 1990, a European registration procedure was performed with another OXC-formulation (“new” Trileptal), that differed slightly from the first product in its` pharmakokinetic properties. The new formulation showed higher C-max values and it was faster absorbed (shorter t-max values). In patients requiring higher dosages we observed more often neurotoxic adverse effects (e.g. dizziness, drowsiness, ataxia etc.) shortly after oral intake thus limiting the possibility to further increase the dosage. Another OXC formulation, that is within the enlarged ranges bioequivalent to the old” Trileptal, is still marketed as Apydan in Finland, Denmark and some other European countries. This formulation possesses even lower C-max values and slower increase of MHD plasma concentration. Methods: We replaced Trileptal in 10 patients with neurotoxic symptoms by the identical dosage of Apydan hypothesising that the tolerability would improve. Patients were followed on a day-by-day practice for two wweks and regularly contacted since then.Results: Seven of ten patients tolerated Apydan without side effects and are therefore continued with that OXC formulation. Further dosage increases were possible in four cases. Three of these and one further patient whose dosage was not elevated reported subsequently a seizure reduction by more than 50%. Conclusions: Our data suggest that in higher dosage range an OXC formulation with a less steep increase of the plasma peak may be advantageous. A slow-release OXC formulation most probably will further improve the therapeutic possibilities with OXC substantially.