... nothing. Before the doctors prescribed Bupropion XL I started taking the remaining part of a previous prescription and within 7 days I was down to 4 cigarettes a day but I ran out of pills. It took over a month to get a new Rx. I am uncertain of what the difference is but after three weeks I have not had any success despite being highly motivated. My question is what dosage, form, brand, etc is the most effective for smoking cessation? I KNOW there is a difference. Thanks