Influence of enzyme inducing antiepileptic drugs on the pharmacokinetics of levetiracetam in patients with epilepsy.

To assess whether levetiracetam elimination is influenced by enzyme inducing antiepileptic drugs (EIAEDs), serum levetiracetam levels were determined at frequent intervals after a single oral 1000mg dose in 15 subjects co-medicated with EIAEDs and 15 matched controls. The EIAED group showed a higher levetiracetam oral clearance (p=0.01) and a shorter half-life (p=0.02) than controls. Although the magnitude of interaction is relatively modest, it could have clinical significance for some patients.

[Interchangeability among therapeutics equivalents of lamotrigine in the treatment of refractory epilepsy patients: risks and benefits]. / Intercambiabilidad entre equivalentes terapéuticos de lamotrigina en pacientes con epilepsia refractaria: riesgos y beneficios.

INTRODUCTION: Epilepsy is a condition characterized by signs and symptoms of neurological disorder. Lamotrigine has been widely used, mainly due to their greater tolerability and lower rate of drug interactions with other antiepileptic drugs however the newest antiepileptic drugs have high cost to patient. In Brazil there are three different sort of pharmaceutical equivalents (reference, generic and similar), and the Brazilian health care authorities offers to users the possibility to receive them free of charge. Moreover these pharmaceutical equivalents can change during the treatment of epilepsy because this authorities buy the cheapest by public tender two or three times a year. AIM: To evaluate the clinical and laboratory findings related to the most frequently used therapeutic equivalents of lamotrigine (reference drugs and similar products). PATIENTS AND METHODS: Two similar formulations (A and B) and one reference (C) were tested in nine epileptic refractory patients. The study was divided into three periods of 42 days, one for each formulation, and medical data about the frequency of seizures, the occurrence of side effects and measurement of plasma concentrations of lamotrigine were collected. RESULTS: The average number of seizures/week and plasma concentration of lamotrigine for formulations A, B and C were not statistically significant differences. Three patients during the use of the formulation C presented mild and transitory side effects. CONCLUSION: Similar or reference drugs showed satisfactory results, however the interchangeability among the formulations raise the difficulty for the management of seizures in refractory epilepsy.