Lamotrigine Now Available in Canada
by Dr. MacIntyre Burnham, President, Epilepsy Ontario, Professor of Pharmacology, University of Toronto and Director of the Bloorview Epilepsy Program
Another new anticonvulsant drug is available for use in Canada. It is called lamotrigine and its trade name is Lamictal®. It was developed by the Burroughs Wellcome Company, which, after the recent round of mergers, has become Glaxo Wellcome Inc.
Lamotrigine has the broadest spectrum of any of the new anticonvulsants. It is effective against not only tonic-clonic (grand mal) and partial seizures, but also against absence (petite mal) attacks. Of the drugs available, only valproate (Depakene®) and the benzodiazepines have an equally broad spectrum of action.
Like most of the recently developed anticonvulsants, lamotrigine is low in toxicity. The main side effect, seen in up to 5% of patients, is a rash. This can be tolerated (it goes away in time) and can be largely avoided by introducing the drug slowly. A few patients report stomach upsets, dizziness or fatigue.
Lamotrigine is involved in a few drug interactions which doctors and parents should know about. It does not change the blood levels of other anticonvulsants, but they change the blood level of lamotrigine. phenytoin (Dilantin®) and phenobarbital, for instance, lower blood levels of lamotrigine, whereas valproate tends to raise them. These interactions are not serious. They simply require an adjustment of the lamotrigine dosage.
At present, lamotrigine is often used as an add on drug or saved for difficult cases, where other drugs have failed. The feeling, however, is that it is quite a good anticonvulsant which will eventually take its place as a main-line drug, along with phenytoin, carbamazepine, and valproate.
Lamotrigine is usually taken in pill form, once or twice per day.
