According to the U.S. Center for Disease Control and Prevention, there were 36,450 drug overdose deaths in the country in 2008. Out of the total number of deaths, the number of deaths due to overdoses on prescription drugs were 20,044.
Pain killing drugs, such as oxycodone, methadone, and hydrocodone, were involved in 14,800 deaths in 2008, according to the CDC. In 1999, around 4,000 people died from overdosing on those types of drugs.
Source: Eryn Brown, “Prescription painkillers outpace heroin, cocaine in OD deaths,” Los Angeles Times, Booster Shots Blog, November 1, 2011.