ATC Group: N02AC Diphenylpropylamine derivatives

Dextromoramide is a powerful opioid analgesic approximately three times more potent than morphine but shorter acting. The main advantage of this drug is that it has a fast onset of action when taken orally, and has a high bioavailability which means that oral dosing produces almost as much effect as injection. It also has a relatively low tendency to cause constipation which is a common problem with opioid analgesics used for cancer pain relief, and tolerance to the analgesic effects develops relatively slowly compared to most other short-acting opioids.

Propoxyphene, a synthetic opiate agonist, is structurally similar to methadone. Its general pharmacologic properties are those of the opiates as a group. The analgesic effect of propoxyphene is due to the d-isomer, dextropropoxyphene. It binds to the opiate receptors and leads to a decrease of the perception of pain stimuli. Propoxyphene possesses little to no antitussive activity and no antipyretic action.

Piritramide is a pure µ-opioid receptor agonist, which has a slightly less analgesic potency than morphine. Analgesia results from activation of the µ-opioid receptors in the spine and the higher pain centres such as the thalamus and cerebral cortex, thereby raising the pain threshold and the sensitivity to pain.