4-Piperidinol, 1-phenethyl-4-phenyl acetate (PEPAP) is a synthetic opioid discovered by Janssen in 1960. PEPAP is an analog of meperidine, it is abused and illegally sold on streets as a "synthetic heroin".

PHENOPERIDINE is an opioid analgesic partly metabolized to meperidine in the liver. It is derived from pethidine by replacing the N methyl by a phenyl propanol chain. It is reputed to be a typical morphine-like analgesic characterized by its high potency, rapid onset of action, the intensity of its peak effect and the short duration of its pharmacological effects. It is used in general anesthesia.

Propiram is an orally administered analgesic with partial morphine-like agonist and weak antagonist properties. Analgesic efficacy of propiram, usually 50 or 100mg, appears comparable to that of standard dosages of other oral opioid drugs [i.e. pentazocine, pethidine (meperidine)] in patients with acute pain of moderate to severe intensity arising from various gynaecological and surgical procedures, and may be superior to codeine in gynaecological and postoperative dental pain. Propiram is a non-addictive analgesic for the relief of moderate-to-severe pain. Propiram reached Phase III clinical trials in the United States and Canada, but was discontinued. Propiram is a partial opioid mu receptor agonist.

Methadyl Acetate is a narcotic analgesic with a long onset and duration of action. Methadyl Acetate is primarily a mu-type opioid receptor agonist and the drug decreases a patient's opioid use by preventing opioid withdrawal. Levacetylmethadol, the enantiomer of Methadyl Acetate, was approved in 1993 by the U.S. Food and Drug Administration for use in the treatment of opioid dependence. In 2001, levacetylmethadol was removed from the U.S. market due to reports of life-threatening ventricular rhythm disorders.

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

Dipipanone are indicated for the management of moderate to severe pain in medical and surgical conditions in which morphine may be indicated. Dipipanone is related to methadone and can be substituted for assorted opioids. The severe or irreversible adverse effects of Dipipanone, which give rise to further complications, include hypotension, hypotension, hependence, agranulocytosis, ischemic colitis, generalized chorea, hypersensitivity hepatitis. It may interact badly with monoamine oxidase inhibitors, which are substances found in some antidepressants and other medication.