Dimepheptanol is one of the phenylpiperidine series, an opioid receptor agonist, which is active as an opioid analgesic. It is also elaborated in a number of close analogues, derivatives or diastereoisomers with similar properties. Dimepheptanol is a synthetic narcotic analgesic that has no accepted medical use in the United States.

Betameprodine is an opioid analgesic under international control according to the UN Single Convention 1961. The stereoisomer alphameprodine was more widely used, however, had a similar classification.

Etorphine was the first potent opiate agonist employed primarily for use in non-domestic and wild species. Etorphine was 500 times as potent as morphine, with a very rapid onset and short duration of action. In morphine-dependent subjects, etorphine suppressed abstinence but for a shorter period than morphine. Etorphine is a full opiate agonist and binds to multiple opiate sites in the central nervous system. It is believed to produce its clinical effects through binding the µ-, δ-, and κ- opiate sites. It has a potent effect on depressing the respiratory centers of the CNS thus resulting in apnea being commonly seen in immobilized animals. Etorphine revolutionized the ability of biologists and veterinarians to safely capture and restrain many species that previously could not be handled. Etorphine is not currently commercially available due to lack of production by the manufacturer.

Hydromorphinol, an opioid, and is a derivative of morphine and possesses similar properties: sedation, analgesia, and respiratory depression. Hydromorphinol is under the control according to US Single Convention 1961.

Methyldihydromorphine is a synthetic narcotic analgesic related to the morphine. This compound has no pharmaceutical value in the US.

Ocfentanil, a compound structurally similar to the opioid analgesic fentanyl, was developed in the early 1990’s with the hope that it would provide a better clinical safety profile than fentanyl. The receptor pharmacology of ocfentanil appears to share pharmacodynamic effects with fentanyl and other μ opioid agonists, including analgesia, sedation, and respiratory depression. In rodents, ocfentanil was approximately 2.5 times more potent as an analgesic than fentanyl and had a shorter duration of action. Because the preclinical research suggested that ocfentanil had a better safety profile than fentanyl, it was selected for clinical evaluation. Like other μ opioid agonists, ocfentanil has been reported to produce itching, nausea, sedation, and severe respiratory depression. Chest pain, psychosis, and agitation have also been reported. In humans, however, ocfentanil had a similar potency (3 ug/kg ocfentanil produced effects that were comparable to 5 ug/kg fentanyl) and side-effects profile as fentanyl so further clinical development was discontinued. Ocfentanil is not approved in any country for medical useand is under national control in Canada, the United Kingdom, and China.

Clonitazene is a synthetic opioid analgesic, structurally related to etonitazene. In the USA clonitazene is a schedule I narcotic controlled substance.