A report ( 52 KB) by the European Medicines Evaluation
Agency recently called for more research into all drugs used to treat epilepsy in children. With more than twenty drugs on the market, both new and old, some prioritisation of work is needed.

Professor Ian Wong and his colleagues at the School of Pharmacy in London investigated patterns of prescribing anti-epileptic drugs (AEDs) to children, in order to find out which drugs are most used, and should be prioritised for research.

From a database which provides a representative sample of about 5% of the UK population, they identified 7,721 patients aged less than 18 years, who were prescribed an AED between 1993 and 2005. (Not all these patients had a diagnosis of epilepsy.)

The overall rate of prescribing AEDs increased by 19% over this period. Sixty-nine percent of all prescriptions were for conventional AEDs; and 31% for newer AEDs.

The most commonly prescribed conventional AED was sodium valproate, which accounted for 36% of all prescriptions in the study. The most commonly prescribed new AED was lamotrigine, which accounted for 20% of all prescriptions.

Over the study period, the proportion of prescriptions for newer drugs increased five-fold. Lamotrigine prescriptions increased the most. Newer medicines are increasingly being prescribed in preference to the older, more tried-and-tested drugs. The researchers, writing in the British Journal of Clinical Pharmacology in June, speculated that this is because the newer drugs are less likely to interact with other medications than the older drugs.

There is often very little systematic information about the long-term safety and efficacy of newer drugs in children. The legal regulatory process for approval of new medicines requires a certain number of studies to establish that the new drugs do work and are as safe as they can be. These usually involve adults first and children only later, as including children in clinical trials is difficult. Therefore, once a drug is licenced in adults, the best dose of the drug to give to a child, and what side effects should be expected in children may not be clear; these then have to be established by trial and error once the drug comes on the market. New medications are usually first prescribed by specialists, not GPs.

Professor Ian Wong and his colleagues called for research into three of the newer drugs to be prioritised: lamotrigine (Lamictal®), topiramate (Topamax®) and levetiracetam (Keppra®).

All three of these drugs are currently licensed to be prescribed to children, lamotrigine from the age of two years, levetiracetam from four years, and topiramate from six years (when taken alone, but from the age of two years when given with another drug). This means trials have been carried out, and dosing schedules and likely side effects identified, for these ages, although data for the very young are still required.

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