¹Oregon Health Sciences University, Portland, Los Angeles; the Los Angeles Clinical Trials, Ore, Los Angeles; the Loma Linda VA Medical Center, Loma Linda, Calif; GlaxoWellcome Research and Development, Research Triangle Park, NC; Clinical Research Atlanta, Stockbridge, Ga; and the Manor House, Largo, Fla.

Correspondence: David H. Gonzales, PhD, Oregon Health Sciences University, 3181 SW Sam Jackson Park Rd, CR115, Portland, OR 97201. E-mail: gonzales@ohsu.edu

^*Funding for the study (ZYB40003) was provided by GlaxoWellcome Inc, Research Triangle Park, NC.

A preliminary account of these data has been submitted in abstract form to the Society for Research on Nicotine and Tobacco, March 21-24, 2001, Seattle, Wash.

Received 28 December 2000; Accepted 14 March 2001.

Abstract

Background: Many persons who attempt to quit smoking have made previous unsuccessful attempts to quit with pharmacologic aids. An understanding of the impact of these previous attempts to quit is vital for selecting medications that may be more successful in a future attempt to quit. In particular, the effect of repeated use of bupropion SR (Zyban; INN, amfebutamone) on abstinence rates has not been studied previously.

Methods: This was a multicenter, randomized, double-blind, placebo-controlled study in 450 smokers who had previously used bupropion in a smoking cessation attempt. The study consisted of a screening phase, a 12-week treatment phase, and a follow-up at month 6. Participants made regular clinic visits throughout the treatment phase during which they received brief counseling sessions to encourage abstinence from smoking. The primary end point was continuous abstinence from smoking from weeks 4 through 7. Secondary efficacy end points were examined throughout the treatment phase and at follow-up after 6 months.

Results: In participants receiving bupropion SR, 27% (61 of 226) remained abstinent throughout the period from weeks 4 through 7 compared with 5% (11 of 224) of participants receiving placebo (P < .001). Significantly (P < .001) more participants who received bupropion SR during the treatment phase remained continuously abstinent from the start of week 4 through month 6 (27 of 226; 12%) compared with participants who received placebo (5 of 224; 2%). Eleven participants receiving placebo (5%) and 19 participants receiving bupropion SR (8%) stopped taking the study medication because of an adverse event.

Conclusions: Bupropion SR is an effective medication for retreatment of smokers who have used bupropion SR previously.