• Phillip O Coffin, Glenn-Milo Santos, Jaclyn Hern, Eric Vittinghoff, Deirdre Santos, Tim Matheson, Grant Colfax, and Steven L Batki.
• San Francisco Department of Public Health, San Francisco, CA, USA.
• Addiction. 2018 Feb 1; 113 (2): 268-278.

Background And AimsMethamphetamine use is increasingly prevalent and associated with HIV transmission. Early-phase human studies suggested naltrexone reduced amphetamine use among dependent individuals. We tested if extended-release naltrexone (XRNTX) reduces methamphetamine use and associated sexual risk behaviors among high-risk methamphetamine-dependent men who have sex with men (MSM).DesignDouble-blind, placebo-controlled, randomized trial of XRTNX versus placebo over 12 weeks from 2012 to 2015.SettingSan Francisco Department of Public Health, California, USA.ParticipantsOne hundred community-recruited, sexually-active, actively-using methamphetamine-dependent MSM. Mean age was 43.2 years; 96% were male, 3% transfemale, and 1% transmale; 55.0% were white, 19.0% African American, and 18.0% Latino.InterventionsXRNTX 380 mg (n = 50) or matched placebo (n = 50) administered by gluteal injection at 4-week intervals.MeasurementsRegression estimated average level and change in level of positive urines during the period 2-12 weeks (primary outcomes) and sexual risk behaviors (secondary outcome).FindingsNinety per cent of visits were completed. By intent-to-treat, participants assigned to XRNTX had similar differences during 2-12 weeks in methamphetamine-positive urines as participants assigned to placebo [incidence rate ratio (IRR) = 0.95, 95% confidence interval (CI) = 0.76-1.20; Bayes factor < 0.3]. Observed urine positivity declined from 78 to 70% in the XRNTX arm and 74 to 64% in the placebo arm. Adherence to injections was 96.7% in the XRNTX arm and 91.3% in the placebo arm. Sexual risk behaviors declined similarly among participants in both arms (all P > 0.05). There were no serious adverse events related to study drug and no differences in frequency of adverse events by treatment arm.ConclusionsNotwithstanding very high medication adherence for this study, extended-release naltrexone does not appear to reduce methamphetamine use or sexual risk behaviors among methamphetamine-dependent men who have sex with men compared with placebo.© 2017 Society for the Study of Addiction.

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