The antiepileptic drug lamotrigine (marketed as Lamictal) is yet another drug that is being used for a different purpose than that for which it was originally intended.

Danish researchers have found that it relieves severe pain following a stroke. They tested it on 30 patients, and found that 200 mg per day reduced pain scores by around 30 per cent.

The only other drug with a proven effect on central poststroke pain (CPSP) is amitriptyline, which comes with a range of serious side effects, point out researchers.

Not unlike lamotrigine, in fact. The drug is honoured with a rare boxed warning, printed in black ink, in the American drug bible, the Physicians' Desk Reference. The warning points out that up to one in every thousand lamotrigine adult patients could develop a life threatening rash, an incidence rate that is greatly increased among children. "Although benign rashes also occur with Lamictal, it is not possible to predict reliably which rashes will prove to be life threatening," warns the PDR.

A significant point, and one apparently overlooked by research team head Troels Jensen, who said: "Patients tolerated lamotrigine well in our study; the only side effect is a rash. . ." (Neurology, 2001; 56: 184-90).

Death aside, other effects of lamotrigine include dizziness, headache, blurred vision, nausea and vomiting. Less common, but more severe, reactions have included multiorgan failure, sudden and unexplained death, and blindness.

"Lamotrigine is clearly not a wonder drug," says Willem Meijler at the Comprehensive Cancer Centre in Groningen, the Netherlands, and clearly a master of the understatement, "but in this group of patients [in the Danish study], it's a major step."

The last word is reserved for Troels Jensen. "Lamotrigine is a welcome addition in our arsenal," he says.

Let's hope that is not a rash statement.