 That number was up from 790 in 1999.Approximately 82 percent of those deaths were listed as accidental, and most deaths involved combinations of methadone with other drugs (especially benzodiazepines).Although deaths from methadone are on the rise, methadone-associated deaths are not being caused primarily by methadone intended for methadone treatment programs, according to a panel of experts convened by the Substance Abuse and Mental Health Services Administration, which released a report titled "Methadone-Associated Mortality, Report of a National Assessment".