Ethylmorphine

Ethylmorphine (3-O-ethylmorphine) is a semi-synthetic opioid analgesic belonging to the substituted morphinan chemical class. It is the 3-ethyl ether of morphine — structurally analogous to codeine (morphine's 3-methyl ether) but with an ethyl group in place of the methyl group at the 3-position. Like codeine, ethylmorphine is a prodrug that is partially converted to morphine through hepatic demethylation, accounting for a significant portion of its analgesic activity.

Ethylmorphine has historically been used as a cough suppressant (antitussive) and mild analgesic, sold under the trade name Dionine in Europe and under various other names. It was incorporated into compound cough preparations in the early-to-mid 20th century and was available in some European countries as late as the 1990s. Its antitussive potency is considered intermediate — more effective than codeine but less potent than morphine — and it was favored in some formulations for its claimed rapid onset of cough suppression.

The clinical use of ethylmorphine declined substantially as regulatory scrutiny of opioid-containing cough preparations intensified and as non-opioid antitussive alternatives became available. It is now largely a historical pharmaceutical curiosity in most Western countries, though it retains limited use in certain European and Asian markets. Ethylmorphine is subject to international narcotic controls as a Schedule I substance under the UN Single Convention on Narcotic Drugs.