The effects of methadone are longer lasting than those of morphine-based drugs. Methadone's effects can last up to 24 hours, thereby permitting administration only once a day in heroin detoxification and maintenance programs. Methadone is almost as effective when administered orally as it is by injection. Tolerance and dependence may develop, and withdrawal symptoms, though they develop more slowly and are less severe than those of morphine and heroin, are more prolonged. Ironically, methadone used to control narcotic addiction is frequently encountered on the illicit market and has been associated with a number of overdose deaths.
Closely related to methadone, the synthetic compound levo-alphacetylmethadol or LAAM (ORLAAM) has an even longer duration of action (from 48 to 72 hours), permitting a reduction in frequency of use. In 1994 it was approved as a treatment of narcotic addiction. Like methadone, LAAM is in Schedule II of the United States Controlled Substances Act.
Buprenorphine has also been used in the treatment of narcotic addiction. In October, 2002, the FDA approved two compounds containing buprenorphine (Subutex® and Suboxone®) for the treatment of narcotic addiction. It is interesting to note that Subutex and Suboxone are in Schedule III of the United States Controlled Substances Act, which allow for their use on an outpatient basis, unlike methadone and LAAM.
Another close relative of methadone is dextropropoxyphene, first marketed in 1957 under the trade name of Darvon. Oral analgesic potency is one-half to one-third that of codeine, with 65 mg approximately equivalent to about 600 mg of aspirin. Dextroproxyphene is prescribed for relief of mild to moderate pain. Bulk dextropropoxyphene is in Schedule II of the United States Controlled Substances Act, while preparations containing it are in Schedule IV. More than 100 tons of dextropropoxyphene are produced in the United States annually, and more than 25 million prescriptions are written for the products. This narcotic is associated with a number of toxic side effects and is among the top 10 drugs reported by medical examiners in drug abuse deaths.