Methadone (Dolophine) is a synthesized molecule with pharmacological actions very similar to those of the OPIOD drug, MORPHINE. Methadone serves an important place in the history of opioid ANALGESICS, since it is one of the first synthesized agents (1939). The ability to synthesize opioid analgesics from simple chemicals diminishes our reliance on natural products (such as morphine, CODEINE, and thebaine) to provide the base for many of the currently used opioid analgesics. Structurally, the drug does not look like morphine. Unlike the rigid fused ring structures of morphine, the structure of methadone is extremely flexible. It bends so that the key portions of the molecule can assume positions similar to those of morphine. The structure of methadone is very similar to that of propoxyphene (Darvon), a weaker opiate widely used to treat mild to moderate pain. It has two stereoisomers, but the (-) isomer is far more active than...