Efficacy of Naltrexone in Women's Smoking Cessation
Condition: Smoking; Smoking Cessation
Study type: Interventional
Phase: Phase 2

Summary: 
      The purpose of the proposed study is to conduct a randomized, double-blind clinical trial to
      compare adjunct treatment with 50 mg oral naltrexone vs. placebo in conjunction with standard
      smoking cessation treatment with nicotine patch and counseling.

      Hypotheses:

        1. Naltrexone will improve smoking cessation quit rates, as measured at the end of active
           treatment (3 months) and during long term follow up (1 year).

        2. Weight and smoking-related variables (i.e., less weight gain, as well as reduced craving
           and withdrawal) will be important factors by which naltrexone improves smoking cessation
           outcome.

        3. These effects are predicted to be stronger in women compared to men.
    

Detailed description: 
      Although women may be particularly susceptible to the damaging effects of chronic cigarette
      smoking, evidence indicates that they may have more difficulty in maintaining smoking
      cessation than men. Given women's reduced response to nicotine replacement and other
      traditional treatments to habitual cigarette smoking, more targeted pharmacotherapy and
      intervention strategies may be necessary to improve their quit rates. Preliminary data by our
      group and others indicate that the opioid antagonist naltrexone may be an effective
      adjunctive pharmacotherapy approach for female smokers. The purpose of the proposed study is
      to conduct a randomized clinical trial to compare adjunct treatment with 50 mg oral
      naltrexone vs. placebo in conjunction with standard smoking cessation treatment with nicotine
      patch and counseling. Participants (N=324) will be randomized to receive either naltrexone or
      placebo starting one week prior to the quit date (25 mg for three days; 50 mg thereafter) and
      continue for 12 weeks after the quit date. The effects of naltrexone will be evaluated during
      the pre-quit date period, initial smoking cessation, relapse prevention, and at one year
      follow-up. It is hypothesized that sex will moderate the effects of naltrexone on outcome,
      with naltrexone improving prolonged abstinence quit rates in women but not in men. The
      secondary goal will be to elucidate the mechanism underlying women's treatment response to
      naltrexone. Weight (relative weight gain and weight concerns) and smoking-related variables
      (reduced cigarette pleasure, taste, craving and relief of negative withdrawal affect) may be
      important factors by which naltrexone improves quit rates in women. Medication compliance,
      psychosocial stress and levels of naltrexone's metabolite, 6-B-naltrexol, will also be
      examined. In sum, the proposed clinical trial will provide a comprehensive study of sex
      differences in response to adjunct treatment with naltrexone for smoking cessation. Given the
      public health concerns and significant health consequences of women's continued high rates of
      smoking, the proposed study may provide important information on a novel treatment strategy
      targeting the endogenous opioid system to selectively aid in women's smoking cessation.
    

Intervention name(s): Naltrexone (drug); Placebo (for Naltrexone)
Intervention type(s): Drug; Drug
Intervention description(s): 50 mg q.d. for 13 weeks; Sugar pill manufactured to mimic Naltrexone tablet
Intervention MeSH terms: Naltrexone
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Triple (Participant, Care Provider, Investigator)
Primary purpose: Treatment
Keywords: Smoking; Smoking Cessation