Characterizing changes in drug use behaviour following supply shortages of 5-MeO-DIPT, alkyl nitrites and new psychoactive substances among men living with HIV in Japan.

Background: Since 2005, Japan has incrementally banned a range of new psychoactive substances (NPS), including 5-MeO-DIPT (5MO; foxy) and alkyl nitrites (AN; rush, poppers) that have commonly been used among men who have sex with men (MSM). After the largest ban in 2014, these drugs were reported to have disappeared from the domestic market. Given that 5MO/AN/NPS use has been prevalent among men living with HIV in Japan, a population largely comprised of MSM, we sought to characterize changes in their drug use behavior following the supply shortages.

Methods: Using data from two waves of a nationwide survey of people living with HIV in Japan in 2013 and 2019-20 (n = 1042), we employed multivariable modified Poisson regression to identify correlates of self-reported reactions to the 5MO/AN/NPS shortages and changes in drug use behavior in 2019-20 vs. 2013.

Results: Among 391 men (96.7% MSM) surveyed in 2019-20, following the supply shortages, 234 (59.8%) stopped using 5MO/AN/NPS, 52 (13.3%) retained access to the supply, and 117 (29.9%) used substitute drugs: most commonly, methamphetamine (60.7%). Individuals who used substitutes were more likely to report unprotected sex (adjusted relative risk [ARR]=1.67; 95% confidence interval [CI]: 1.13-2.47) as well as low (ARR=2.35; 95% CI: 1.46-3.79) and lower middle (vs. upper middle to high) socioeconomic status (ARR=1.55; 95% CI: 1.00-2.41). The prevalence of past-year methamphetamine use (ARR=1.93; 95% CI: 1.11-3.35) and self-reported uncontrollable drug use (ARR=1.62; 95% CI: 1.07-2.53) were significantly higher in 2019-20 compared to 2013.

Conclusion: Following the supply shortages, approximately one-fifth of our participants used methamphetamine as a substitute for 5MO/AN/NPS. Methamphetamine use and perceived uncontrollable drug use also appeared to have increased at the population level after the supply shortages. These findings suggest a potentially harmful substance displacement effect of the aggressive ban. Harm reduction interventions are needed in this population.