Access to adult-use cannabis reduced demand for prescription codeine – study

US states which have legalised adult-use cannabis have seen a reduction in demand for prescription codeine, according to a new study. 

Published this week in Health Economics, a multi-institutional study led by University of Pittsburgh and Cornell University scientists, finds a significant reduction in pharmacy-based codeine distribution in states that have legalised recreational cannabis use. 

Codeine is an opioid which is often prescribed for chronic pain, but has a high potential for misuse. According to the World Health Organisation (WHO) opioids account for more than 70% of global drug-related deaths each year. 

Twenty-one US states have passed recreational cannabis laws and legislatures in other states are considering similar measures.

The study is among the first to separately examine the impact of recreational cannabis laws on shipments of opioids to hospitals, pharmacies and other endpoint distributors.

Previous studies have focused on medical cannabis laws or use of opioids by subsets of consumers, such as Medicaid beneficiaries.

The researchers analysed data from the Drug Enforcement Administration’s Automation of Reports and Consolidation Orders System (ARCOS) which tracks the flow of controlled substances in the US.

They found a reduction of 26% in pharmacy-based distribution of codeine and a 37% reduction after recreational cannabis laws have been in effect for four years.

There was, however, minimal impact on codeine distribution by hospitals which often have less permissive policies than pharmacies, and on distribution of other opioids such as oxycodone, hydrocodone and morphine in any setting.

Senior author Coleman Drake, PhD, assistant professor of health policy and management at Pitt’s School of Public Health, commented: “This finding is particularly meaningful. Among prescription opioids, codeine misuse is especially high. Our findings suggest recreational cannabis use may be a substitute for codeine misuse.”

Lead author Shyam Raman, a doctoral candidate in Cornell’s Jeb E. Brooks School of Public Policy, said: “A reduction in the misuse of opioids can save lives.

“Our research indicates that recreational cannabis laws substantially reduce distribution of codeine to pharmacies, an overlooked potential benefit to legalising recreational cannabis use.”

While cannabis and opioids can both be used to minimise chronic pain symptoms, they aren’t equivalent in their impact on health.                   

“Increasing legal access to cannabis may shift some consumers away from opioids and towards cannabis,” added Johanna Catherine Maclean, PhD, of George Mason University. 

“While all substances have some risks, cannabis use is arguably less harmful to health than the non-medical use of prescription opioids.”

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