LAS VEGAS—Extended-release combination oxycodone/naloxone is associated with a cardiovascular risk no higher than that seen for extended-release morphine or extended-release oxycodone among patients without histories of major cardiovascular events, according to a retrospective cohort study of patients in the United Kingdom.

An extended-release combination oxycodone and naloxone is approved in the United Kingdom, noted lead author Laura Wallace, MPH, of Purdue Pharma LP in Stamford, Connecticut, and coauthors.

“There have been theoretical concerns among regulatory agencies that peripheral mu opioid antagonists might increase the risk of cardiovascular events,” the investigators explained. “These concerns are based on potential effects of opioid withdrawal on the autonomic nervous system, including changes in hemodynamic parameters that could increase the risk of cardiovascular events in susceptible patients.”Before the new study, however, there has been “little literature to support or refute this,” they noted.

The study included 46,883 patients. In all three treatment groups, risk factors for cardiovascular events were common and included hypertension, diabetes, and hyperlipidemia, the authors reported. “The incidence of major events was low and similar across all treatment groups, at 1.26 per 100 patient-years for OXN [extended-release oxycodone/naloxone], 1.38 for MOR [extended-release morphine], and 1.14 for OXY [extended-release oxycodone].”

Hazard ratios (HRs, adjusted for age, sex, comorbidities, concomitant medications, and duration of use) for OXN vs. MOR were 0.97 (95% CI: 0.7-1.4) and 0.86 (95% CI: 0.5-1.5) for any cardiovascular events and major events, respectively, they reported. Adjusted HR for OXN vs. OXY were 0.99 (95% CI: 0.7-1.4) and 1.34 (95% CI: 0.8-2.4) for any and major cardiovascular events, respectively.