"Three primary scenarios characterize current reports of methadone-associated mortality:
"1. In the context of legitimate patient care, methadone accumulates to harmful serum levels during the first few days of treatment for addiction or pain (that is, the induction period before methadone steady state is achieved or tolerance develops).
"2. Illicitly obtained methadone is used by some individuals who have diminished or no tolerance to opioids and who may use excessive and/or repetitive doses in an attempt to achieve euphoric effects.
"3. Methadone - either licitly administered or illicitly obtained - is used in combination with other CNS depressant agents (such as benzodiazepines, alcohol, or other opioids)."
Center for Substance Abuse Treatment, "Methadone-Associated Mortality: Report of a National Assessment," May 8-9, 2003, CSAT Publication No. 28-03 (Rockville, MD: Center for Substance Abuse Treatment, Substance Abuse and Mental Health Services Administration, 2004), p. 24.