Dihydromorphine is a semi-synthetic opioid derived from morphine. dihydromorphine is a moderately strong analgesic and is used clinically in the treatment of pain and is also the active metabolite of dihydrocodeine. Dihydromorphine acts as an agonist at the μ-opioid (mu), δ-opioid (delta) and κ-opioid (kappa) receptors. Dihydromorphone is approved for clinical use in the United States, Europe, and Japan; and sold under the brand name Dilaudid. Similar to morphine, and other morphine derivatives, hydromorphone has a high potential for addiction and abuse and is listed as a Schedule II drug in the United States Controlled Substances Act of 1970 (and similarly regulated in other countries).

Pholcodine is an opioid that has been widely used worldwide since 1950 for the treatment of non-productive cough in children and adults. Illicit drug. 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.