The Ohio Department of Health says methadone is responsible for one of every 10 accidental drug overdose deaths in the state. The department says a contributing factor is a dramatic increase in the amount of methadone prescribed since the late 1990s. Retail methadone sales increased more than 800 percent from 2000 through 2010 as the use of methadone to treat chronic pain increased. 155 methadone overdose deaths were reported in 2010, the most recent year of available data. The Centers for Disease Control says methadone accounts for nearly one-third of prescription painkiller deaths nationally. But that number appears to have peaked nationally and in Ohio in 2007.