Effect of restricting the legal supply of prescription opioids on buying through online illicit marketplaces: interrupted time series analysis

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Objectives – In 2014 the US Drug Enforcement Agency (DEA) rescheduled hydrocodone combination products (HCPs) to restrict supply and misuse. Our study aimed to examine the effects of this change on the illicit prescription opioid trade conducted via anonymous online markets known as ‘cryptomarkets’.

Setting – Longitudinal data collected directly from 31 of the world’s largest cryptomarkets operating from October 2013 to July 2016.
Main outcome measures – Sales: number of online transactions; and availability: advertised and active listings for prescription: opioids, sedatives, steroids, stimulants, and illicit opioids.

Design – Three part design: (1) a descriptive analysis of the proportion of total transactions, advertised and active listings within different drug categories; (2) an interrupted time series analysis of opioid prescription sales on cryptomarkets originating from within the US, set against the comparable products originating both within and outside the US; (3) a longitudinal analysis of the composition of the prescription opioid market.

Results – The HCP schedule change in October 2014 immediately preceded a rise in the proportion of the US cryptomarket drug trade attributable to prescription opioids, with no accompanying significant changes in other drug categories. In July 2016 the US prescription opioid cryptomarket represented 13.7% of all drugs sales (95% confidence interval 11.5% to 16.0%) compared to a modelled estimate of 6.7% of all trade (95% confidence interval 3.7% to 9.6%) had the change not occurred. This corresponds to 4 percentage point yearly increase in amount of trade that prescription opioids represent in the US market, set against no corresponding changes for comparable products or for prescription opioids sold outside the US. This change was first observed for sales, and later observed for product availability. There was also a change in the composition of the prescription opioid market: fentanyl was the least purchased product in Q3 2014; then the second most frequently purchased by July 2016.

Conclusions – The hydrocodone scheduling change coincided with a significant, sustained increase in illicit opioid trading on online anonymous markets in the US. These changes were not observed for other product groups or in other countries. The schedule change in HCPs may therefore have led to an increase in the illicit supply of prescription opioids. Further, there was a subsequent movement from hydrocodone toward more potent forms of prescription opioids, particularly oxycodone and fentanyl. These unintended consequences highlight some of the potential problems associated with supply side drug restrictions imposed in a context of high consumer demand.

Bibliographical metadata

Original languageEnglish
Number of pages7
JournalBritish Medical Journal
Early online date13 Jun 2018
Publication statusPublished - 2018

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