The new anti-epileptic drugs: Their current role in the management of epilepsy

Four anti-epileptic drugs (AEDs) have arrived on the United Kingdom market in recent years: vigabatrin, lamotrigine, gabapentin and topiramate. Vigabatrin is used as a second-line treatment in partial seizures, producing a 50% seizure reduction in up to half of patients treated, with up to 5% of these patients becoming seizure-free. Tolerance may develop during long-term treatment in up to a quarter of patients. The drug is associated with behavioural side effects that can be reduced by starting treatment with a low dose and titrating slowly over several weeks. Lamotrigine is used as add-on therapy in patients with refractory partial seizures and has recently had its licence extended for use in patients with newly diagnosed partial and tonic-clonic seizures. Clinical trials have shown a reduction of up to 25% in the frequency of partial seizures, but few become seizure-free. The drug is well-tolerated and the commonest side effect is an idiosyncratic skin rash. A few fatalities due to disseminated intravascular coagulation and liver failure have, however, been linked to treatment with lamotrigine. Gabapentin is used as add-on treatment in patients with refractory partial seizures with a mean reduction in seizure frequency of up to 21%. The drug is usually well-tolerated and no idiosyncratic adverse effects have yet been identified. Topiramate has recently been licensed as an add-on in patients with refractory partial seizures. Clinical trials have shown a reduction in the frequency of partial seizures in up to 50% of patients, with up to 5% becoming seizure-free. Nephrolithiasis, weight loss and sedation have been associated with this drug, but no idiosyncratic reactions have been identified as yet. Although the role of established and newer AEDs in the long-term prognosis of epilepsy is not yet clearly defined, there is clearly a need for new drugs for patients who do not respond or respond only partially to existing agents.