The aim of this study was to investigate the influence of concomitant antiepileptic drugs (AEDs) on brivaracetam (BRV) trough serum concentrations, the lowest serum concentration reached by BRV before the next dose is taken.
A total number of 368 routinely collected blood samples from 148 inpatients from Mara Hospital (Bethel Epilepsy Center) and von Bodelschwingh Foundation Bethel, both in Germany, were retrospectively evaluated. Analyses showed that BRV trough serum concentrations were significantly lower in patients with strong enzyme-inducing AEDs (carbamazepine (Tegretol®), phenytoin (Dilantin®), and/or phenobarbital/primidone (Solfoton®/Mysoline®, -49%), but were not affected by concomitant intake of oxcarbazepine (Trileptal®) or eslicarbazepine (Aptiom®). Age and gender did not have a significant effect. An alternative model analyzing the BRV level-to-dose ratios yielded comparable results.
According to the research team, the results from routine therapeutic drug monitoring data indicate that the effect of enzyme-inducing AEDs on BRV serum concentrations is stronger than the 20%-30% reduction in BRV exposure previously reported in pharmacokinetics studies. Further research is necessary to evaluate these differences and to elucidate possible clinical consequences.