The Food and Drug Administration has approved a new use for GlaxoSmithKline’s anti-epilepsy drug Lamictal, adding one of the most serious forms of epilepsy to its indications.

Lamictal (lamotrigine) is now approved to treat primary generalised tonic-clonic seizures, also known as "grand mal" seizures, in patients aged two and older. Grand mal seizures account for around 20% of all epilepsy cases.

Victor Biton, director of the Arkansas Epilepsy Program, notes there are few treatments approved for generalised seizures, and fewer approved for both PGTC and partial seizures.

People who experience PGTC seizures become stiff, lose consciousness, and jerk repetitively. Patients may fall to the ground, bite their tongue, and lose bladder control. Serious injury, including broken bones, can occur. The seizure will typically last for a few minutes and then be followed by a period of drowsiness, confusion, headache, and sleep. For some people who have this type of seizure, it can take many hours to fully recover.

Approval of Lamictal as add-on therapy in patients with PGTC seizures was based on a 117-patient study in which Lamictal was given to patients whose grand mal seizures were not well controlled, even while taking one or two other anti-seizure medications.

Lamictal significantly reduced PGTC seizures by 66%, compared to 34% for the placebo group (p=0.006).

In addition, significantly more patients receiving Lamictal as maintenance therapy experienced at least a 50% reduction compared to placebo (72 % versus 49 %, p<0.05).

While there is thought to be a fair amount of off-label use of Lamictal in grand mal patients in the USA, the new approval should heighten physician’s confidence in using the drug in this setting.

Lamictal is currently GSK’s third biggest-selling product, with sales of $862 million in the first half of 2006, up 17%. However, growth is expectedly to tail off now that the drug has started to lose patent protection in Europe and other parts of the world. It is should start to face generic competition in the USA in 2008.