A randomized, controlled trial to assess the efficacy and safety of a transdermal delivery system of nicotine/mecamylamine in cigarette smokers.

Aims: To determine the efficacy and safety of nicotine transdermal therapy co-administered with the nicotine antagonist, mecamylamine, compared to a nicotine transdermal patch alone (21 mg nicotine + 6 mg mecamylamine, 21 mg nicotine + 3 mg mecamylamine, and 21 mg nicotine + 0 mg mecamylamine).

Design: Multi-center (n = 4), double-blind, randomized, parallel group, repeat-dose study.

Setting: Clinical laboratory.

Participants: A total of 540 subjects were enrolled into the study-135 from each of four sites; 180 patients in each of three treatment arms.

Intervention: Treatment was administered for the first 6 weeks of the 8-week study. Patients were instructed to continue smoking for the first 2 weeks of treatment.

Measurements: The primary efficacy parameter was 4-week continuous abstinence after the quit date, confirmed with an expired carbon monoxide of < 10 parts per million.

Findings: Analysis of the 4-week continuous abstinence for the intent-to-treat population showed overall rates of 29% (nicotine + 6 mg mecamylamine), 29% (nicotine + 3 mg mecamylamine) and 23% (nicotine only) using the slip definition which allows smoking in the first 2 weeks after the quit date. Statistical analyses revealed no significant treatment differences. Analyses using the strict definition (no smoking after the quit date) yielded similar non-significant group differences (29%, 27%, 26%).

Conclusion: If adding mecamylamine to nicotine replacement therapy (NRT) improves the chances of success at stopping smoking, the results of this study suggest that the effect is very small.