A lawsuit claiming Pfizer’s smoking-cessation drug Chantix caused a suicide was filed in Indiana federal court earlier this month, and a major law firm is investigating similar legal action against the manufacturer.

Philadelphia-based Levin, Fishbein, Sedran & Berman — not a party in the Indiana suit but whose partner Arnold Levin was a member of the committee that negotiated the $4.5 billion Vioxx (rofecoxib) settlement against Merck — has a number of clients with potential claims involving Chantix (varenicline tartrate), according to Michael Weinkowitz, a mass tort and class-action attorney at the firm. Investigations into the cases continue, he said.

Chantix was approved in May 2006 and at least 4 million people have been prescribed the drug in the U.S., Pfizer has said. Since its launch, the product has experienced strong uptake, making $193 million in U.S. sales during the first quarter of 2008.

The drug has been suspected of being associated with suicidal thoughts and aggressive and erratic behavior. The FDA issued a MedWatch report and an early communication highlighting the issues last November. Pfizer added a warning to Chantix physician labeling Jan. 18 recommending that patients be observed for suicidal thoughts or behaviors, agitation and depressed mood.
 
The Indiana lawsuit, Linda Collins v. Pfizer, Inc., accuses Pfizer of contributing to the death of her husband, who began taking Chantix last October. He died of a self-inflicted gunshot wound Jan. 3.

The suit contends that Pfizer’s revised Chantix label is inadequate to properly warn patients of the drug’s risks. According to the complaint, the man had no history of mental illness.

The plaintiff alleges that Pfizer should have known about the safety issues with the drug because of knowledge the firm had of other products, which the lawsuit says have a similar mechanism of action — such as antidepressant Zoloft (sertraline HCl).