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).

Methylnaltrexone bromide, (17s)- (methylnaltrexone bromide), a quaternary amine of the pure narcotic antagonist naltrexone, is a peripherally-acting selective mu-opioid antagonist. Methylnaltrexone antagonizes opioid binding at mu-opioid receptors, half-maximal inhibitory concentration (IC50) of 70 nM. It has a relatively lower affinity for κ-opioid receptors (IC50 575 nM), and it does not interact with δ-receptors or orphanin FQ receptors. Approved by FDA in the United States under the trade name Relistor, methylnaltrexone bromide is indicated for the treatment of opioid-induced constipation in patients with advanced illness who are receiving palliative care, when the response to laxative therapy has not been sufficient. Restricted ability to cross the blood-brain barrier allows methylnaltrexone bromide to function in tissues such as the gastrointestinal tract, decreasing the constipating effects of opioids without impacting opioid-mediated analgesic effects on the central nervous system.

Normethadone is a derivate of opioid analgetic methadone, used as component of antitussive drops in Canada. Illicit drug.

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.

MOVANTIK (naloxegol) is a peripherally-acting mu-opioid receptor antagonist indicated for the treatment of opioid-induced constipation (OIC) in adult patients with chronic noncancer pain. It is being investigated for the treatment of constipation as a side effect of prescription opioid pain medicines.

Diphenoxylate is an opioid drug used for the treatment of acute diarrhea. The drug is used in combination with atropine and marketed under names Lomotil and Diphenoxylate hydrochloride and atropine sulfate. Diphenoxylate is biotransformed in man by ester hydrolysis to diphenoxylic acid (difenoxine), which is biologically active and the major metabolite in the blood. The drug exerts its action by activating mu opioid receptors of intestinal mucosa.

Normorphine is an opiate analog, specifically the N-demethylated derivative of morphine. It was first described in the 1953 as part of an effort to characterize N-substituted morphine analogs. Normorphine has relatively little opioid activity, but it is a useful intermediate for the production of more potent morphine analogs. It is also a major metabolite of morphine.

Cebranopadol is a novel analgesic nociceptin/orphanin FQ peptide (NOP) and opioid receptor agonist. Cebranopadol, by its combination of agonism at NOP and opioid receptors, affords highly potent and efficacious analgesia in various pain models with a favorable side effect profile. Cebranopadol displays analgesic, antiallodynic and antihyperalgesic properties in several rat models of acute nociceptive, inflammatory, cancer and neuropathic pain. Unlike morphine, cebranopadol did not disrupt motor coordination and respiration at doses within and exceeding the analgesic dose range possessing a broader therapeutic window than classical opioids. It is currently in clinical development for the treatment of severe chronic nociceptive and neuropathic pain.

Mirfentanil was developed as CNS analgesic with a short duration of action. It induced antinociception predominately through mu opioid receptors. It was shown that at doses larger than those, which exert opioid effects, mirfentanil had nonopioid analgesic effects. The drug was successfully encapsulated in liposomes having a variety of compositions. The lipid composition of the formulation was varied to optimize the stabilization of liposomes and the encapsulation of solutes. Mirfentanil participated in phase II clinical trials for the treatment of pain. However, this study was discontinued.

Normorphine is an opiate analog, specifically the N-demethylated derivative of morphine. It was first described in the 1953 as part of an effort to characterize N-substituted morphine analogs. Normorphine has relatively little opioid activity, but it is a useful intermediate for the production of more potent morphine analogs. It is also a major metabolite of morphine.