Frequency of drug combinations between enzyme-inducing first-generation antiepileptic drugs and inducible drugs in patients with epilepsy.

Objective: The objective of the study was to systematically assess, through the analysis of administrative data, the frequency of combinations of first-generation enzyme-inducing (EI) antiepileptic drugs (AEDs) with drugs frequently prescribed in patients with epilepsy whose metabolism is induced by EIAEDs.
Methods: From the population of Tuscany (a region in Italy of about 3,750,000 habitants), patients who had been treated with at least one first-generation EIAEDs (carbamazepine, phenytoin, phenobarbital, and primidone) and had received prescriptions of an inducible non-AED (NON-AED) included in a prespecified list of 103 inducible drugs were identified.
Results: At the index date, 9221 patients with epilepsy were treated with at least one traditional EIAED, and there were 2538 drug combinations between EIAEDs and NON-AEDs, which may result in potentially serious clinical consequences, and 3317 combinations with NON-AEDs that have their metabolism consistently increased.
Conclusions: Patients with epilepsy treated with traditional EIAEDs are at a very high risk of drug interactions.
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