I had a family member who became suicidal on Chantix. I was wanting to quit at the same time so when given the option I went with Zyban (bupropion hydrochloride) and had quit by the second week.

What was really incredible though was right from the start I felt fantastic, like I spent all day in a flow state.

The doctor stopped the prescription after (I think) 8 weeks and I didn't start smoking again. Many years later I learned it is prescribed for ADHD and also as an antidepressant.