Despite preclinical evidence supporting the role of the endogenous opioid system in the
reinforcing effects of nicotine, the efficacy of the opioid antagonist naltrexone (NTX) as a
tobacco dependence treatment remains unresolved. Research is needed to identify those smokers
for whom NTX will have the strongest beneficial effects on smoking behavior.
The research bridges existing knowledge of genetic, pharmacologic, and behavioral responses
to nicotine, and translates this knowledge to treatment for tobacco dependence. The immediate
goal was to test whether genetic variation in the mu-opioid receptor gene predicts the
effects of naltrexone (NTX) on nicotine reinforcement.