Targeting the Opioid Receptors: A Promising Therapeutic Avenue for Treatment in "Heavy Drinking Smokers"

Aims: Despite a general decline in tobacco use in the last decades, the prevalence of tobacco smoking in individuals with alcohol use disorder (AUD) remains substantial (45-50%). Importantly, the co-use of both substances potentiates the adverse effects, making it a significant public health problem. Substantial evidence suggests that AUD and Tobacco use disorder (TUD) may share common mechanisms. Targeting these mechanisms may therefore provide more effective therapy. Numerous studies describe a potential role of the endogenous opioid system in both AUD and TUD. Reviewing this literature, we aim to evaluate the efficacy of molecules that target the opioid system as promising therapeutic interventions for treating alcohol and tobacco co-use disorders. Methods: We provide a synthesis of the current epidemiological knowledge of alcohol and tobacco co-use disorders. We evaluate clinical and preclinical research that focuses on the regulation of the endogenous opioid system in alcohol, nicotine, and their interactions. Results: The epidemiological data confirm that smoking stimulates heavy drinking and facilitates alcohol craving. Pharmacological findings suggest that treatments that are efficacious in the dual addiction provide a beneficial treatment outcome in comorbid AUD and TUD. In this regard, MOP, DOP and NOP-receptor antagonists show promising results, while the findings prompt caution when considering KOP-receptor antagonists as a treatment option in alcohol and tobacco co-use disorders. Conclusions: Existing literature suggests a role of the opioid system in sustaining the high comorbidity rates of AUD and TUD. Molecules targeting opioid receptors may therefore represent promising therapeutic interventions in 'heavy drinking smokers.'