Even though an outside panel of experts confirmed the link between suicide and treatment of bipolar disorder with antiseizure drugs, the panel voted against putting a strong "black box" warning on the drugs' labels.
Now an analysis of new data by University of Chicago researcher Robert D. Gibbons, PhD, and colleagues suggests that epilepsy drugs actually decrease the risk of suicide in patients with bipolar disorder.
"The present analysis provides no evidence that anti-epileptic drugs increase risk of suicide attempts in patients with bipolar disorder," they conclude. "Most anti-epileptic drugs and lithium are associated with reduction in suicide-attempt rates relative to pretreatment levels in patients who are ultimately prescribed these drugs."
Eleven drugs were included in the Gibbons analysis:
There's no definitive proof these drugs actually help people with bipolar disorder. But doctors who prescribe the drugs often find them very helpful for bipolar disorder patients for whom other treatments fail.
Bipolar disorder itself greatly increases suicide risk. A 2006 study found that every year, 40 out of every thousand bipolar patients try to kill themselves.
Gibbons and colleagues, whose previous work has cast doubt on the link between antidepressants and suicide, analyzed data on nearly 48,000 bipolar patients in a large medical-claims database.
They found that patients who received the antiepileptic drugs had the same number of suicide attempts as those who did not receive such drugs or who received lithium, a first-line treatment for bipolar disorder.
Interestingly, patients treated with antiepileptic drugs had far more suicide attempts before treatment than those not treated with the drugs, suggesting that these drugs are often given to patients with more severe bipolar disorder.
Despite a higher rate of pretreatment suicide attempts, those treated with antiepileptic drugs had a lower rate of suicide attempts after treatment.
Gibbons reports having served or currently serving as an expert witness for the U.S. Department of Justice, Wyeth, and Pfizer Pharmaceuticals. The Pfizer case, Gibbons reports, involved Neurontin, one of the drugs considered in the study.
The study appears in the December issue of Archives of General Psychiatry.