Accidental overdose deaths in New Mexico caused by prescription drugs increased at a higher rate than those caused by illegal drugs such as heroin and cocaine, according to a new study covering a 10-year period.

Opioid pain relievers -  such as codeine, Demerol and morphine -  accounted for the majority of the deaths caused by prescription drugs in the study from the May American Journal of Preventive Medicine.

“The increasing role of opioid painkillers in unintentional drug overdose deaths suggests that overdose prevention efforts would be well targeted at this drug class,” said lead researcher Mark Mueller, an epidemiologist with the Centers for Disease Control and Prevention.

Using statewide medical examiner reports, Mueller and colleagues determined that of the 765 prescription drug-related overdose deaths in New Mexico from 1994 to 2003, more than three-fourths were caused by opioid pain relievers. A third of deaths were caused by tranquilizers, and one-quarter were caused by antidepressants. (Because some deaths were caused by multiple drugs, the total exceeds 100 percent.)

Unintentional prescription drug overdoses accounted for 1.9 deaths out of 100,000 deaths at the beginning of the study period, rising to 5.3 overdose deaths out of 100,000 deaths. This represented a 179-percent increase over a decade, compared with the 121-percent rise in unintentional overdose deaths due to illegal drugs. New Mexico has had the highest drug-induced death rate in the United States since the 1990s, according to background information in the study.

Sidney Schnoll, clinical professor of internal medicine and psychiatry at the Medical College of Virginia, acknowledged that prescription drug abuse is a growing problem. “However, I would be concerned about extrapolating these findings. New Mexico is a relatively rural state, and one of the things we know about prescription drug abuse, particularly prescription opioid abuse, is that it is more of a problem of rural areas than urban areas,” Schnoll said.

Although this is the first study to evaluate the contribution of prescription drugs to the unintentional overdose death rate in New Mexico, the authors say that such deaths are increasing around the world in tandem with increasing medical and nonmedical use of prescription drugs, especially narcotic pain relievers.

“While we would all agree on the value of properly prescribed and used opioids, this study illustrates the need to reinforce proper prescribing practices and usage of prescription drugs, particularly opioid painkillers,” said Mueller. “It will also be important to find new ways to prevent deaths due to prescription drugs acquired through street diversion.”

Mueller MR, Shah NG, Landen MG. Unintentional prescription drug overdose deaths in New Mexico, 1994-2003. Am J Prev Med 30(5), 2006.