Chantix Meltdowns?

I know four (4) people on Chantix, a prescription medication intended for aiding in quitting smoking. Pfizer, the drug's maker, has announced it will add additional warnings on the label regarding recently discovered side effects including suicidal tendencies, aggressive behavior, mood swings, and so forth. What's even more weird, is that three of these people have "wigged out" on me recently, all over stupid things that normally wouldn't be an issue for any of them. One was so flaked out that it's probably ended that friendship forever. I'm starting to see a pattern emerge. Read more about this at the Pfizer web site.