Normal therapeutic doses of methadone could cause sudden cardiac death, Reuters reported Jan. 22.

Researcher Sumeet S. Shugh and colleagues at Oregon Health and Science University studied autopsy records of Portland residents who died of sudden cardiac arrest between 2002 and 2006. After excluding victims whose death was not unexpected, deaths from non-cardiac causes, and victims who had a history of recreational drug use or used high doses of methadone, the researchers found that 22 victims had taken normal doses of methadone for pain or maintenance for opioid addiction. The remaining 106 victims tested negative for methadone.

In 23 percent of the deaths among the therapeutic methadone users and 60 percent of the non-methadone cases, a heart abnormality was found that could have triggered a fatal cardiac incident. "The significantly lower prevalence of cardiac disease in the case group implicates methadone, even at therapeutic levels, as a likely cause of sudden death," the researchers concluded.

The study was published in the January 2008 issue of the American Journal of Medicine.