Within-week associations between alcohol and other substance use and interaction with naltrexone among sexual and gender minority men in San Francisco, California, USA.

Aims: To determine whether there were within-week associations between changes in alcohol use and changes in cannabis, cocaine or amphetamines use and, if so, to ascertain whether these associations varied by naltrexone use among adult sexual and gender minority men (SGMM) with mild and moderate alcohol use disorder (AUD).

Design: Secondary analyses of data from the Say When study, a double-blind placebo-controlled trial comparing targeted oral naltrexone (50 mg) to placebo for AUD over 12 weeks.

Setting: Procedures were conducted at the San Francisco Department of Public Health from May 2015 to November 2020, in San Francisco, California, USA.

Participants: 98 of 120 SGMM who reported substance use beyond alcohol.

Measurements: Mixed effects logistic regression models tested associations between alcohol exposures [ethyl-glucuronide (EtG)-positive urine screens, past-week binge drinking and past-week binge drinking frequency] and same-week use of other substances (positive urine screens for cannabis, cocaine or amphetamines), adjusting for age, race/ethnicity, income, depression score and treatment assignment. Associations by treatment assignment (naltrexone or placebo) were also evaluated.

Findings: Having a positive EtG urine screen was associated with higher odds of positive urine screens for cannabis [adjusted odds ratio (aOR) = 2.93, 95% confidence interval (95% CI) = 1.37-6.30, P = 0.006) or cocaine (aOR = 3.08, 95% CI = 1.52-6.23, P = 0.002). Each additional binge drinking day was associated with higher odds of having a positive urine screen for cocaine (aOR = 1.29, 95% CI = 1.04-1.60, P = 0.018). Among those receiving naltrexone, greater binge drinking days was associated with increased odds of having a positive urine screen for cocaine (aOR = 1.64, 95% CI = 1.18-2.27, P = 0.003), while results for cannabis and amphetamines were not statistically significant.

Conclusions: Among adult sexual and gender minority men enrolled in a clinical trial, alcohol use was positively associated with cannabis and cocaine use. Naltrexone may mitigate cocaine use in this group by moderating binge drinking or diminishing the rewarding effects of cocaethylene. Findings highlight the potential of targeted naltrexone as an intervention to address alcohol and cocaine co-use and improve treatment outcomes in this underserved group.