ATC Group: R05DA Opium alkaloids and derivatives

Codeine is a centrally acting weak analgesic. Codeine exerts its effect through μ opioid receptors, although codeine has low affinity for these receptors, and its analgesic effect is due to its conversion to morphine. Codeine, particularly in combination with other analgesics such as paracetamol, has been shown to be effective in acute nociceptive pain. The anti-tussive activity of codeine is probably due to its depressant effect on the medullary cough centre in the brain.

Dextromethorphan is a non-opioid antitussive drug. The major metabolite of dextromethorphan, dextrorphan, binds with high affinity to σ-receptors to produce its antitussive activity without exhibiting the classic opiate effects that occur from binding into μ- and δ-receptors. In larger than therapeutic doses, dextrorphan is also an antagonist of N-methyl-D-aspartate (NMDA) receptors.

Ethylmorphine (ethylmorphine) is a derivative of morphine with analgesic and antitussive effect. It acts by activating the opioid receptors and thus has a direct influence on the CNS system.

Hydrocodone is a semisynthetic narcotic analgesic and antitussive with multiple actions qualitatively similar to those of codeine. Most of these involve the central nervous system and smooth muscle.

Normethadone is a derivate of opioid analgetic methadone, used as component of antitussive drops.

Noscapine is a benzylisoquinoline alkaloid from plants of the poppy family, without painkilling properties. Noscapine is often used as an antitussive medication. Noscapine can increase the effects of centrally sedating substances such as alcohol and hypnotics. Noscapine, and its synthetic derivatives called noscapinoids, are known to interact with microtubules and inhibit cancer cell proliferation. Mechanisms for its antitussive action are unknown, although animal studies have suggested central nervous system as a site of action. Furthermore, noscapine causes apoptosis in many cell types and has potent antitumor activity against solid murine lymphoid tumors (even when the drug was administered orally) and against human breast and bladder tumors implanted in nude mice. Antifibrotic effect of noscapine based on novel mechanism, which it shows through EP2 prostaglandin E2 receptor-mediated activation of protein kinase A.

Pholcodine is an opioid that has been widely used for the treatment of non-productive cough in children and adults. Pholcodine is a cough suppressant with mild sedative but little analgesic activity. Additionally pholcodine is a marker for sensitization to neuromuscular blocking agents (NMBA) and is intended for use as a diagnostic tool in NMBA-induced anaphylaxis.