Some seizure drugs may not raise the risk of suicide for patients with epilepsy as feared, but they more than double the risk for people with depression, researchers reported on Wednesday.
They found evidence that the drugs do not make it more likely that patients with epilepsy will commit suicide. But patients take the drugs for a range of other conditions and some of these had a 65 percent higher risk.
In 2008 the U.S. Food and Drug Administration warned that epilepsy drugs may increase the risk of suicide.
The new study, led by Dr. Alejandro Arana of Risk MR Pharmacovigilance Services in Zaragoza, Spain, culled records from 5 million patients in Britain treated from July 1988 through March 2008. They included 8,212 suicide attempts.
"Our findings suggest that treatment with antiepileptic drugs does not confer an additional risk of suicide-related events among patients with epilepsy," they wrote in the New England Journal of Medicine.
The drugs tested include topiramate, sold by Johnson & Johnson under the Topamax brand, and also included as part of Vivus's experimental obesity drug Qnexa.
They include Cephalon's Gabitril, known generally as tiagabine, UCB Pharmaceuticals' Keppra or levetiracetam, H. Lundbeck's Sabril or vigabatrin, Pfizer's Neurontin or gabapentin and Lyrica or pregabalin, GlaxoSmithKline's Lamictal or lamotrigine, Novartis' Trileptal or oxcarbazepine and Eisai's Zonegran or zonisamide.
They also included valproate, sold by Abbott Laboratories as Depakine and Sanofi-Aventis as Epilim, and carbamazepine, sold as Carbatrol by Shire and Tegretol by Novartis.
The researchers found that people with epilepsy, depression or the abrupt mood swings of bipolar disorder who were not taking epilepsy drugs had a higher likelihood of suicide attempts in the first place.
But taking one of the seizure drugs did not increase the risk of suicide-related events for people with epilepsy or bipolar disorder, or among patients whose epilepsy was combined with depression.
"In general, our results do not confirm the findings previously reported by the FDA," the Arana team concluded.
Last week a separate group of researchers, who also studied British patients, concluded that attempted suicide or self-harm only occurred in epilepsy patients taking newer drugs that have been linked to a risk of depression.
That study, in the journal Neurology, tracked 453 suicide attempts or incidents of self-harm, a small fraction of the number in the Arana survey.