About 71,000 people were admitted to U.S. hospitals for prescription-drug overdoses in 2006, up from approximately 43,000 in 1999, according to a new report.

Reuters reported April 6 that researcher Jeffrey H. Coben of the West Virginia University School of Medicine and colleagues found that accidental poisonings involving opioids, sedatives, and tranquilizers increased 37 percent, compared to a rise of 21 percent for accidental poisonings involving other substances.

The report noted that unintentional poisoning is now the second-leading cause of accidental injury death in the U.S.

Coben and colleagues said that urban, middle-aged women seem especially vulnerable to prescription-drug overdoses.

The rate of intentional poisonings involving prescription opioids, sedatives and tranquilizers also more than doubled during the seven-year study.

Hospitalizations for methadone poisoning increased more than for any other drug.

The study was published in the April 2010 issue of the American Journal of Preventive Medicine (PDF).