Last September, The Dallas Morning News reported that an intoxicated local man was shot in the head by his girlfriend's neighbor. The girlfriend claimed that Pfizer's smoking cessation drug Chantix caused a change in his behavior that led to a chain of events resulting in his death.

It was a sensational story, and though the connection between Chantix and the man's death was tenuous at best, the girlfriend's claim raised questions about the side effects of the drug ...