Drug companies often exclude people with depression from clinical trials, even though it is well known among physicians that depression often coincides with other disorders. By purposefully eliminating this cohort from early testing stages, drug manufacturers hope to gain faster FDA approval, but they may be shooting themselves in the foot once the treatment is mass-marketed and its widespread effects are better known.
Pfizer learned this lesson the hard way after the company omitted thousands of smokers with depression from their clinical trials for Chantix, a smoking-cessation drug, only to receive a restrictive “black box” warning label after the FDA received thousands of complaints, including erratic behavior, and in some cases suicide, once the drug was approved.
Even though 40 percent of smokers are depressed compared to just seven percent of the general population, Pfizer’s decision to exclude smokers with depression is not out of the ordinary. Sanofi-Aventis and Boehringer Ingelheim did the same thing with the weight-loss drug rimonabant (Acomplia) and the “female Viagra” drug flibanserin, respectively.
“Smoking— similar to other types of addictions — is to some extent a genetic propensity, and similar linkages exist with depression and suicidal risk,” explains ACSH's Dr. Gilbert Ross. “Therefore, how can you justify barring them from a clinical trial relating to smoking cessation?”
The FDA is now requiring that Pfizer complete a large follow-up study for Chantix to include a reasonable proportion of participants with mental health problems as the agency works to draft guidelines for assessing suicide risk during clinical trials.