Documenting major shifts in methamphetamine and heroin prices and purity in metropolitan and rural Victoria, Australia
Previous work has shown dramatic declines in estimated purity-adjusted prices of methamphetamine and heroin in Melbourne that accompanied major increases in harms. Our study builds on this work to examine trends in the purity of, and prices paid for, methamphetamine and heroin from 2009 to 2020 in metropolitan Victoria and rural Victoria from 2016 to 2020.
The drug purity series for methamphetamine and heroin were derived from the analysis of 47679 illicit drug seizures conducted by the Victoria police between 2009 and 2020. Data on methamphetamine and heroin purchases were collected from 1302 participants in the Melbourne Injecting Drug User cohort study (SuperMIX) and 806 participants from ‘VMAX’, a cohort of people who use methamphetamine in metropolitan and rural Victoria, Australia. We adjusted prices to 2020 Australian dollars (AUD) utilizing the All Groups CPI. These datasets were then merged to create drug price series spanning the same time frame. We then generated purity-adjusted prices for both metropolitan (2009-2020) and rural Victoria (2016-2020). The significance of the changes in the rolling purity, price and purity-adjusted prices were determined using F-tests, for each year of the study period.
An increase in the average purity of methamphetamine seizures from 20% was observed from 2009, with median purity over 80% from 2012 onwards. In contrast, the average purity of heroin remained consistently low until 2018, hovering around 20%-25%. Subsequently, it experienced a notable increase to 47% by 2019, before undergoing a slight decline thereafter. The observed increase of methamphetamine purity in rural Victoria occurred approximately one year after the increase in metropolitan Melbourne. The average unadjusted PPG for methamphetamine in metropolitan Melbourne rose from AUD232 in 2009 to AUD623 in 2012, followed by a decline until 2019 and a subsequent increase. From 2016-2020, the average PPG for methamphetamine was higher in rural, compared to metropolitan Melbourne. For heroin, metropolitan Melbourne maintained a stable average PPG until 2018, experiencing minimal fluctuations, holding steady at AUD224 from 2009 until 2018. Subsequently, there was an increase in average PPG to AUD324 by 2020.
The increase in unadjusted methamphetamine prices observed in the early stages of the study was offset by increases in purity such that the purity adjusted price declined from AUD1300 (per pure gram) in 2009 to AUD450 in 2015, after which it stabilized. In contrast, the average purity-adjusted PPG for heroin was stable from 2009 (AUD1300 per pure gram) through to 2014 after which it declined to AUD650 by 2020.
The overall declines in both methamphetamine and heroin purity-adjusted prices suggests that people who use these drugs receive more drug for a given purchase. These changes match closely trends seen in some key harms such as opioid overdose. The relationship between these market parameters and harms needs to be further understood.
