Caution urged on switching antiepileptic drugs

PRESCRIBERS treating patients with oral antiepileptic drugs (AEDs) are being urged to consider carefully any decision to switch between different manufacturers’ products for a particular drug.

This advice comes in the November MHRA drug safety update.

Concerns about switching AEDs have been raised by both patients and prescribers – particularly in regard to the narrow therapeutic index of some of the drugs and the potentially serious consequences of therapeutic failure. These concerns were reviewed by the Commission on Human Medicines (CHM) along with other reports on potential harm arising from switching AEDs in patients previously stabilised on a branded product to a generic.

The CHM concluded that reports of loss of seizure control and/or worsening of side-effects around the time of switching could be explained as chance associations but a causal role could not be ruled out in all cases.

The CHM has advised that AEDs should be classified into three categories based on therapeutic index, solubility, and absorption to help prescribers and patients decide whether it is necessary to maintain continuity of supply of a specific manufacturer’s product.

The MHRA alert provides advice on prescribing agents from each of these categories and this can be accessed here

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