4-Methylaminorex is a stimulant drug, synthesized by McNeil Laboratories as an appetite suppressant. Its development was discontinued in favor of aminorex, which was withdrawn from the market when its use was linked with the development of fatal pulmonary hypertension. 4-Methylaminorex exists as four stereoisomers (±)-cis and (±)-trans. In neurochemical and behavioral studies trans-4S,5S-isomer was the most potent isomer followed by the equally effective cis-isomers, whereas trans-4R,5R-isomer was relatively ineffective. The racemic cis-4-methylaminorex has been reported to be the most frequently encountered form in illicit samples The drug is known under street names "U4Euh" or "Ice", is used a a stimulant and is classified as a schedule I substance. Neurochemical data suggest that behavioral effects of the isomers of 4-methylaminorex are related to drug-induced dopamine release.

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.

Drotebanol is an opioid drug developed in Japan and used for the treatment of cough under the name Metebanyl, although it is now no longer used. Drotebanol possess CNS activity and is considered to be narcotic in many countries.

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).

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.

Thebacon (dihydrocodeinone enol acetate, trade name Acedicon) is semisynthetic opioid analgetic and antitussive compound. Boehringer-Ingelheim merketed Acedicon for the treatment of cough. Thebacon is a Schedule I drug, that has not got approved use in US.