The FDA is close to adding a black box warning to epilepsy drugs after a safety review showed that they increase patients’ risk of suicidal thoughts and behavior. Rather than impacting sales of such drugs for the treatment of epilepsy, the warning will represent a greater threat to sales of these drugs for indications where alternative drug classes are available.

The FDA has analyzed data from 199 placebo-controlled trials of 11 epilepsy drugs involving a total of 43,892 patients. The results of the analysis showed that 0.43% of patients taking the drugs committed suicide, or thought about doing so, compared with 0.24% of patients taking a placebo. The FDA’s proposal to add a black box warning to epilepsy drugs regarding the increased risk of suicidal thoughts and behavior will be considered by outside advisors to the FDA at a meeting on July 10.

Although the FDA has stated that it identified no increased risk for three of the 11 drugs studied, the agency intends to apply the black box warning to all epilepsy drugs. This decision has led to some criticism, with Pfizer disputing the FDA’s analysis on the basis that its drug Lyrica (pregabalin) is different from others in the class. A retrospective analysis of 199 non-identical study protocols and a large spectrum of co-morbidities contains many variables, making it difficult to draw firm conclusions that are applicable to an entire class of drugs.

Neurologists are likely to perceive the potential consequences of untreated epilepsy as a far greater risk than the small risk of suicidal thoughts and behavior. Without taking treatment, epilepsy patients can experience recurrent seizures, possibly leading to serious injury and automobile accidents. For this reason - alongside the fact that no other drug classes are approved for the treatment of epilepsy - we do not expect the FDA’s black box warning to exert a negative impact on future sales of these drugs for the treatment of epilepsy, which are predicted to continue growing to around $4.2 billion by 2016 across the 7MM.

Nevertheless, in view of the high prevalence of depression in epilepsy patients, the warning will force neurologists to monitor their patients more closely. In the short term at least, the challenge will be to manage patients’ fears surrounding the warnings and their subsequent compliance to treatment.

Related research: Commercial Insight: Epilepsy - Companies committed to the cause will reap the benefits