Varenicline
"I took chantix for 2 weeks. The first couple of days were ok, though I felt a little edgy and short tempered. By the 6th day I had a bad case of "no filter". I said whatever I was thinking no matter how rude it happened to be, ( I work at a Hospice House). It just came out. By the 8th day I didn't feel like I was ready to quit but I did really grumpy and argumentative.  It just didn't work for me."