It is worth noting, however that anti-epileptic drugs are not just used to treat epilepsy. Doctors frequently prescribe these medications to treat migraine, bipolar disorder and other psychological illnesses, as well as some chronic neuropathic pain conditions. Making matters worse, patients with these illnesses are already at increased risk for suicidal thoughts and behavior.
The new warnings result from an investigation, launched by the FDA in 2005, into reports of suicidal ideation associated with 11 anti-seizure medications. The drugs involved in the FDA investigation are Carbamazepine (marketed as Carbatrol, Equetro, Tegretol, Tegretol XR), Felbamate (marketed as Felbatol), Gabapentin (marketed as Neurontin), Lamotrigine (marketed as Lamictal) Levetiracetam (marketed as Keppra), Oxcarbazepine (marketed as Trileptal), Pregabalin (marketed as Lyrica), Tiagabine (marketed as Gabitril), Topiramate (marketed as Topamax), Valproate (marketed as Depakote, Depakote ER, Depakene, Depacon), and Zonisamide (marketed as Zonegran).After analyzing 199 studies of the drugs, in what is called a meta-analysis, the FDA investigators found that 0.43 percent of drug-treated patients experienced suicidal thoughts or behavior, compared with 0.22 per cent of placebo-takers. That translates into approximately two patients in every 1,000 having suicidal ideation. In total, 28,000 people were given anti-seizure medications in the studies, and another 16,000 received placebos.
This serious adverse affect was reported by study participants as soon as one week after starting on the anti-seizure medications, and as late as 24 weeks afterwards. Importantly, the FDA investigators also found that the risk for suicidal thoughts and behavior while on the medications was highest in people with epilepsy, but between the remaining groups of patients, such as migraineurs, and people with bipolar disorder, there was no marked difference.
The FDA pointed out that while the 11 drugs noted above were the only agents studied, they "expect that all medications in the antiepileptic class share the increased risk of suicidality."
In its statement, the FDA issued this advice: "Patients who are currently taking antiepileptic medicines should not make any changes without first talking to their health care provider," as stopping or skipping these medications can result in seizures.
Some common symptoms that can indicate someone is thinking of suicide include: withdrawing from family and friends; becoming depressed, or experiencing a worsening of pre-existing depression; talking about self-inflicting injury or ending your life; becoming preoccupied with dying and death; and giving away valued personal items.
The FDA is advising doctors to warn their patients of the increased risk for suicidal thoughts and behaviour, and asking them to be aware of possible worsening of pre-existing mood disorders such as depression, and uncharacteristic changes in behaviour.
For its part, Health Canada says it is evaluating this new information, and is also working with the drug manufacturers to develop "class labeling' so that all anti-epileptic drugs carry the same warnings. They anticipate the new labelling will be finalized within a month. Similarly, the FDA expects to have the warnings in place in the US this summer.