Prescriptions for dangerous alternatives to OxyContin are soaring, showing that a crackdown on the popular painkiller has failed to curb Canada’s opioid crisis.

OxyContin, a brand-name version of oxycodone, was once the top-selling long-acting opioid in Canada. But it became a lightning rod in the early 2000s as reports of addiction and overdose exploded, prompting every province except Alberta in 2012 to stop funding the drug and its reformulated, tamper-resistant version, OxyNEO, which is difficult to crush or chew for a quick high.

Similar restrictions were not placed on other addictive opioids, a move many experts say had the unintended consequence of shifting patients from one drug to another and escalating the prescription-drug crisis.

The shift to other opioids has helped Purdue Pharma Canada, the manufacturer of OxyContin and OxyNEO, remain a key player in Canada’s opioid market. Hydromorph Contin, also made by Purdue, is now the most popular long-acting opioid in Canada, with prescriptions reaching 1.6 million last year, up 60 per cent since 2011, according...