Increasing diversion of methadone in Vancouver, Canada, 2005-2015 (2018)

Background and aim: Although methadone, an opioid agonist, has been an effective medication used to treat opioid use disorder for over 40 years, recent studies have found that methadone was identified in more than a quarter of prescription opioid-related deaths among people who use illicit drugs in Vancouver, Canada. Thus, we sought to longitudinally examine the availability of diverted methadone among people who inject drugs (PWID).
Design and methods: Data were collected from three prospective cohorts of PWID in Vancouver, Canada between December 2005 and May 2015. Multivariable generalized estimating equation logistic regression was used to identify temporal trends in the immediate availability of diverted methadone (defined as the ability to acquire illicit methadone in < 10 min).
Results: A total of 2092 participants, including 727 (34.8%) women, were included in the present study. In the multivariable analyses after adjusting for a range of potential confounders, later calendar year (adjusted odds ratio [AOR] = 1.21 per year; 95% confidence interval [CI]: 1.19-1.23) was independently and positively associated with reporting immediate availability of diverted methadone.
Conclusions: We observed a significant increase in the reported availability of diverted methadone among PWID over a ten-year follow-up period. Further research is needed to identify strategies to limit methadone diversion and assess the impact of alternative medications that are equally effective but safer, such as buprenorphine/naloxone.
Highlights:
Methadone has been implicated in opioid-related deaths among illicit drug users.
We examined the availability of diverted methadone among people who inject drugs.
The availability of diverted methadone significantly increased between 2005 and 2015.
Strategies to limit methadone diversion and evaluate alternatives are needed.