Objective. - To assess the level of nicotine replacement, evidence of nicotine toxicity, and withdrawal symptom relief with placebo and 11-, 22-, and 44-mg/d doses of transdermal nicotine. A secondary objective was to assess short- and long-term smoking cessation rates. Design. - Randomized, double-blind, placebo-controlled inpatient/outpatient trial. Subjects. - Seventy-one cigarette smokers stratified according to light (n=23), moderate (n=24), and heavy (n=24) smoking rates. Interventions. - After baseline measures were obtained, subjects were randomly assigned to placebo or an 11- , 22-, or 44-mg/d dose of transdermal nicotine and admitted to a special hospital unit for intensive inpatient treatment of nicotine dependence. During the 6-day inpatient stay, daily nicotine and cotinine levels were determined from trough and peak blood samples. Outpatient patch therapy continued for 7 weeks following the hospital stay, and those initially assigned to placebo were randomly assigned to 11 or 22 mg/d. At week 4, the dosage of those initially assigned to 44 mg/d was reduced to 22 mg/d. Main Outcome Measures. - Percentage of replacement of cotinine was calculated by dividing the steady-state levels attained during patch therapy by the corresponding baseline levels. Abstinence from smoking was verified by expired air carbon monoxide. Withdrawal symptoms and nicotine toxicity were assessed daily through questionnaires during the inpatient stay. Follow-up visits were at 3, 6, 9, and 12 months. Results. - There was a statistically significant relationship between baseline smoking rate and baseline trough and peak blood cotinine levels (r(s)=0.39, r(s)=0.45; P<.001 in both instances). A dose-response relationship was observed with higher patch doses, which produced a higher percentage of cotinine replacement and better withdrawal symptom relief. Only one subject (a light smoker assigned to the 44-mg dose) developed signs of nicotine toxicity. There was a positive association between the week 2 patch dose and the biochemically confirmed abstinence at the end of patch therapy (P=.007) but not for subsequent follow-up times. A higher percentage of cotinine replacement was associated with the higher 8-week smoking abstinence rate (P=-.03), an association not found at long-term follow-up. Conclusion. - A 44-mg/d dose of nicotine patch therapy appears to be safe for use in heavy smokers. Cigarette smoking rates can be used to estimate the initial nicotine patch dose. Monitoring blood cotinine levels at baseline and steady state can be used for assessing the adequacy of nicotine replacement. Withdrawal symptom relief can be improved with more complete nicotine replacement. Achieving a greater percentage of nicotine replacement may increase the efficacy of nicotine patch therapy.
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