Varenicline
"I tried Chantix 2 yrs ago.  I was 63 and smoked a pack to a pack and a half a day since I was 18.  Had quit cold turkey 2ce for more than 2 yrs each time, but ended up going back to the cigarettes. No one ever told me there was support, so I just took it as prescribed.  During the first week I had NO ability to cut down, much less quit.  I was going thru a breakup of a 20 yr relationship and did not get suicidal feelings, I got homicidal ones.  I am soooo not a violent person, and wanting to hurt someone was something I had never experienced.  I became really agitated and short tempered.  Finally gave up after 2 mos (never did manage to totally quit smoking).  Took me about 3 mos to get back to normal."