The MHRA has advised that antiepileptic drugs should be classified into 3 categories with respect to switching between brands:
Category 1 – Ensure patients are maintained on a specific manufacturer’s product: phenytoin, carbamazepine, phenobarbital, primidone
Category 2 - The need for continued supply of a particular manufacturer’s product should be based on clinical judgement, taking account of factors such as seizure frequency and treatment history: valproate, lamotrigine, perampanel, retigabine, rufinamide, clobazam, clonazepam, oxcarbazepine, eslicarbazepine, zonisamide, topiramate
Category 3 – Usually unnecessary to ensure that patients are maintained on a specific manufacturer’s product unless there are specific reasons such as patient anxiety, risk of confusion or dosing errors: levetiracetam, lacosamide, tiagabine, gabapentin, pregabalin, ethosuximide, vigabatrin
Initiation and withdrawal of therapy must only be managed by a specialist.