Anatomical Therapeutic Chemical Classification System
Fentanyl is a potent µ-opioid analgesic with rapid onset of analgesia and short duration of action. Its primary therapeutic actions are analgesia and sedation and is approximately 100-fold more potent than morphine as an analgesic. Secondary effects of fentanyl on central nervous system (CNS), respiratory and gastro-intestinal function are typical of opioid analgesics and are considered to be class effects.
Ketobemidone is a powerful synthetic opioid painkiller. Its effectiveness against pain is in the same range as morphine, and it also has some NMDA-antagonist properties imparted, in part, by its metabolite norketobemidone. This may make it useful for some types of pain that do not respond well to other opioids.
Pethidine is a synthetic opioid analgesic similar with similar actions to morphine. Like other opioids, pethidine binds to opioid receptors and exerts its principal pharmacological actions on the central nervous system where its analgesic and sedative effects are of particular therapeutic value. Pethidine also causes the release of histamine from mast cells resulting in a number of allergic-type reactions.