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This move follows a CHM review of spontaneous adverse reaction reports received by the MHRA and publications that reported potential harm arising from switching to a generic anticonvulsant in patients previously stabilised on a branded product. The CHM concluded that while loss of seizure control and/or worsening of side-effects around the time of the switch could be chance associations, a causal role of switching could not be ruled out in all cases.
Antiepileptic drugs grouped into 3 categories based on potential risk
The categories, which are based on therapeutic index, solubility and absorption, are as follows:
- Category 1 (phenytoin, carbamazepine, phenobarbital, primidone) – prescribers should ensure patients are maintained on a specific brand or a specific manufacturer’s generic product
- Category 2 (valproate, lamotrigine, perampanel, retigabine, rufinamide, clobazam, clonazepam, oxcarbazepine, eslicarbazepine, zonisamide, topiramate) – prescribers should make a decision about the need to maintain patients on a particular manufacturer’s product based on clinical judgment and consultation with the patient and/or carer, taking into account factors such as seizure frequency and treatment history
- Category 3 (levetiracetam, lacosamide, tiagabine, gabapentin, pregabalin, ethosuximide, vigabatrin) – it is usually unnecessary to maintain patients on a specific manufacturer’s product unless there are specific concerns such as patient anxiety and risk of confusion or dosing errors.
Where it is deemed necessary for a patient to be maintained on a specific manufacturer’s product, prescribers should either specify a brand name or use the generic drug name plus the name of the relevant manufacturer.
The CHM has also advised pharmacists that if it is necessary to supply a product from a different manufacturer to ensure continuity of supply of an anticonvulsant they should first discuss and agree the matter with both the prescriber and the patient or carer.
View anticonvulsant drug records
Further Information: MHRA
