NCIt definition : A synthetic diphenyl propionate derivative structurally related to methadone, Propoxyphene
Napsylate acts as a central narcotic and analgesic agent by interaction with mu opioid
receptors, but with less selectivity then morphine. The dextro-isomer has analgesic
effect, while the levo-isomer exerts an antitussive effect. The napsylate salt allows
better dosage formulation than the hydrochloride salt. (NCI04);