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.

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.

Hydroxypethidine, an opioid analgesic is an opioid receptor agonist. Hydroxypethidine is under the control of narcotic drugs according to US Single Convention 1961.

Trimeperidine (promedol) is the earliest and mostly studied opioid analgesic. Trimeperidine stimulates opioid receptors in the central nervous system. Compared with morphine, it has a weaker and shorter analgesic effect, less affects the respiratory, vomiting and vagal centers, does not cause smooth muscle spasm (except for the myometrium), and has a moderate antispasmodic and hypnotic effect. It is used to treat severe pain syndrome, acute left ventricular failure, pulmonary edema, cardiogenic shock, preparation for surgery, childbirth, high fever, post-transfusion complications, poisoning with atropine, barbiturates, barium, gasoline, boric acid, strong acids, carbon monoxide, turpentine, formalin, formalin. It has several side effects. Administration of this substance is associated with the development of life-threatening conditions accompanied by the suppression of respiration center. Analgesic trimeperidine (promedol) was included into the health care kits by various Ministries of the Russian Federation at different times.

Alphameprodine (ACSCN 9604) is an opioid analgesic classified by the United States Drug Enforcement Administration under Schedule I of illegal substances. The stereoisomer betameprodine is similarly classified, however alphameprodine is more widely used (both are referred to as Meprodine). Alphameprodine is a structural analogue of meperidine. It exerts physiological effects characteristic of opioids, such as analgesia, euphoria and sedation, as well as itching, nausea, and respiratory depression.

Dimenoxadol is an opioid analgesic which produces typical opioid effects such as analgesia and sedation. It is structurally similar to methadone and is a benzilic acid derivative. In the United States it is classified as a Schedule I controlled drug.

Dimethylthiambutene is the synthetic narcotic analgesic agent. It has analgesic effect similar to those of meperidine. The (+)-enantiomer of dimethylthiambutene is more active than the (-)-isomer. Dimethylthiambutene clinically compared with meperidine (pethidine), but maintains the dependence-producing capability of morphine. It has had illicit use in Japan in the past. Dimethylthiambutene is under international control according to the UN Single Convention 1961 and its amendments, Schedule I.

Phenadoxone hydrochloride is one of some forty amino-ketones and amino-esters related to amidone. The compound is a very potent analgesic for the rat; by the subcutaneous route it is more active than either morphine or amidone. In spite of this its acute toxicity to mice is lower than that of amidone and its therapeutic index is therefore correspondingly higher, giving a wider margin of safety. Side effects in dogs, such as narcosis, sedation, and general depression, were much less with phenadoxone than with amidone or morphine. Nausea and vomiting did not occur after phenadoxone in non-tolerant dogs. Clinical results show that for relieving certain types of pain in human subjects it is a potent analgesic that compares favorably with morphine and amidone. At therapeutic dose levels undesirable pharmacological effects, such as cardiac depression and vasomotor disturbance, are absent, and it is only at extremely high dose levels that untoward effects occur. However, the drug has a strong respiratory depressant action when given in high doses; it should be used with special caution if injected intravenously.