• Psychiatry Clinical Trials
• Substance-Related Disorders
• Smoking Cessation

• Psychiatry Clinical Trials
• Substance-Related Disorders
• Psychiatry
• Smoking Cessation

A randomized, double-blind, placebo-controlled study from researchers in Brazil and Australia has demonstrated the prowess of N-acetylcysteine (NAC) in reducing cigarette smoking for individuals previously refractory to smoking cessation efforts. Although the small number of patients precludes a definite conclusion, the potential of NAC in smoking cessation therapy is indicated. The study presenter was Eduardo Prado, MD, Londrina State University, Londrina, Brazil [APA 2014 (poster NR-8218)].

NAC is a cysteine prodrug that functions to restore glutamate homeostasis and promotes glutathione synthesis by virtue of its antioxidant activity. It has also been implicated in reducing the nicotine craving in cigarette smokers. However, the latter has not been rigorously assessed. Forty subjects were enrolled in the present 12-week study. Thirty-four subjects who had failed previous attempts to stop smoking were randomly assigned to receive 3000 mg/day of NAC (n=17) or placebo (n=17) for 12 weeks. Eleven subjects in the NAC group and 7 in the placebo group completed the study.

The primary outcome was smoking cessation as gauged by examination of the daily log of cigarette smoking maintained by each subject and objectively by measurement of exhaled carbon monoxide (CO_EXH) at 1, 2, and 3 months. At each monthly visit, each subject also received a medical examination and behavior group therapy counseling and provided self-assessed ratings of his or her withdrawal symptoms and adverse effects.

Subjects in the two groups did not differ in marital status, age, years of education, gender makeup, and smoking behavior variables that included onset of tobacco use, years of smoking, and Fagerström Test for Nicotine Dependence (Table 1). Other similarities included lifetime consumption of cigarettes, prevalence and types of depressive disorders, and alcohol consumption.

Significant decreases in the primary outcomes of daily smoking and CO_EXH were evident in those receiving NAC (Table 2). Withdrawal symptoms and adverse effects were similar in both groups (data not shown in poster).

Analysis of other variables revealed a significant difference in the Hamilton Depression Rating Scale score, with higher scores at baseline and 12 weeks for those receiving placebo (Table 3).

The results support the potential of NAC as a smoking cessation agent and should serve as a springboard for more clinical trials to substantiate this role of NAC.

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