Objective: To determine the efficacy and safety of clonidine versus placebo in smoking cessation.
Design: Single-center, randomized, double-blind, parallel-design comparison of transdermal clonidine with behavior modification, transdermal clonidine without behavior modification, placebo with behavior modification, and placebo without behavior modification.
Setting: Outpatient, university-based ambulatory care facility.
Patients: One hundred fifty generally healthy, highly nicotine-dependent cigarette smokers.
Intervention: Clonidine was given as the transdermal patch initiated 72 hours prior to smoking-cessation attempts and continued for six weeks thereafter. Clonidine was given at a dose of 0.2 mg/d for patients weighing more than 150 pounds (> 67.5 kg) and at a dose of 0.1 mg/d for patients weighing less than 150 pounds (< 67.5 kg). Behavior modification consisted of a total of 12 one-hour structured group training sessions. Patients not receiving behavior modification received printed material, which included the "Help Quit Kit" and the "I Quit Kit" from the American Cancer Society.
Main outcome measures: Smoking-cessation rates were assessed at 6, 12, 24, and 52 weeks of follow-up. In addition, adverse reactions to clonidine or placebo were evaluated.
Results: Clonidine with behavior modification was statistically superior to the other three treatment groups but only at 6 weeks of follow-up. There were no differences in smoking-cessation rates among any of the treatment groups at any other follow-up intervals. Patients receiving behavior modification, regardless of whether they received clonidine, had better quit rates than patients not receiving behavior modification at all follow-up times except 52 weeks. Women receiving clonidine had significantly better quit rates than men receiving clonidine at all follow-up visits. Clonidine was associated with a significantly higher incidence of adverse effects than placebo (52 vs. 11 percent). However, the number of smokers withdrawing from the study was not greater with clonidine compared with placebo (9 vs. 7 percent, respectively).
Conclusions: Clonidine is probably not effective as a pharmacologic adjunct to behavior modification in smoking cessation. It may have a potential role in women smokers who do not respond to or cannot tolerate more traditional smoking-cessation therapies.