Butorphanol is a morphinan-type synthetic agonist–antagonist opioid analgesic developed by Bristol-Myers. Butorphanol is most closely structurally related to levorphanol. Butorphanol is available as the tartrate salt in injectable, tablet, and intranasal spray formulations. The tablet form is only used in dogs, cats and horses due to low bioavailability in humans.
Etonitazene, also known as EA-4941 or CS-4640, is a benzimidazole opioid, first reported in 1957, that has been shown to have approximately 1,000 to 1,500 times the potency of morphine in animals.
Levorphanol is an opioid medication used to treat moderate to severe pain. It is the levorotatory enantiomer of the compound racemorphan. Its dextrorotatory counterpart is dextrorphan.
Morphinan is the prototype chemical structure of a large chemical class of psychoactive drugs, consisting of opiate analgesics, cough suppressants, and dissociative hallucinogens, among others. Typical examples include compounds such as morphine, codeine, and dextromethorphan (DXM). Despite related molecular structures, the pharmacological profiles and mechanisms of action between the various types of morphinan substances can vary substantially. They tend to function either as μ-opioid receptor agonists (analgesics), or NMDA receptor antagonists (dissociatives).
Levomethorphan (LVM) (INN, BAN) is an opioid analgesic of the morphinan family that has never been marketed. It is the L-stereoisomer of racemethorphan (methorphan). The effects of the two isomers of racemethorphan are quite different, with dextromethorphan (DXM) being an antitussive at low doses and a dissociative hallucinogen at much higher doses. Levomethorphan is about five times stronger than morphine.
Methorphan comes in two isomeric forms, each with differing pharmacology and effects:
Piritramide(R-3365, trade names Dipidolor, Piridolan, Pirium and others) is a synthetic opioid analgesic that is marketed in certain European countries including: Austria, Belgium, Czech Republic, Slovenia, Germany and the Netherlands. It comes in free form, is about 0.75x times as potent as morphine and is given parenterally for the treatment of severe pain. Nausea, vomiting, respiratory depression and constipation are believed to be less frequent with piritramide than with morphine, and it produces more rapid-onset analgesia when compared to morphine and pethidine. After intravenous administration the onset of analgesia is as little as 1–2 minutes, which may be related to its great lipophilicity. The analgesic and sedative effects of piritramide are believed to be potentiated with phenothiazines and its emetic (nausea/vomiting-inducing) effects are suppressed. The volume of distribution is 0.7-1 L/kg after a single dose, 4.7-6 L/kg after steady-state concentrations are achieved and up to 11.1 L/kg after prolonged dosing.
Metopon is an opioid analogue that is a methylated derivative of hydromorphone which was invented in 1929 as an analgesic.
Nalorphine, also known as N-allylnormorphine, is a mixed opioid agonist–antagonist with opioid antagonist and analgesic properties. It was introduced in 1954 and was used as an antidote to reverse opioid overdose and in a challenge test to determine opioid dependence.
Metazocine is an opioid analgesic related to pentazocine. While metazocine has significant analgesic effects, mediated through a mixed agonist–antagonist action at the mu opioid receptor, its clinical use is limited by dysphoric and hallucinogenic effects which are most likely caused by activity at kappa opioid receptors and/or sigma receptors.
Phenazocine is an opioid analgesic drug, which is related to pentazocine and has a similar profile of effects.
Furethidine is a 4-phenylpiperidine derivative that is related to the clinically used opioid analgesic drug pethidine (meperidine), but with around 25x higher potency. According to another source, Furethidine is 500/30 = 16.7 x the potency of pethidine.
Levophenacylmorphan is a morphinan derivative that acts as an opioid agonist. It has potent analgesic effects and is around 10x more potent than morphine. Adverse effects associated with its use are those of the opioids as a whole, including pruritus, nausea, respiratory depression, euphoria and development of tolerance and dependence to its effects.
Drotebanol (Oxymethebanol) is a morphinan derivative that acts as an opioid agonist. It was invented by Sankyo Company in Japan during the 1970s. It is synthesised from thebaine.
14-Phenylpropoxymetopon (PPOM) is an opioid analogue that is a derivative of metopon which has been substituted with a γ-phenylpropoxy group at the 14-position. PPOM is a highly potent analgesic drug several thousand times stronger than morphine, with an even higher in vivo potency than etorphine. The 14-phenylpropoxy substitution appears to confer potent μ-opioid agonist activity, even when combined with substitutions such as N-cyclopropyl or N-allyl, which normally result in μ-opioid antagonist compounds.
Methyldesorphine is an opioid analgesic. First synthesized in Germany in 1940 and patented in the US in 1952, it has a high potential for abuse as with any potent opioid agonist, and is sometimes found along with desomorphine as a component of the home-made opioid mixture known as "Krokodil" used in Russia and the neighboring former Soviet republics. It is approximately 15 times more potent than morphine as an analgesic but if the 6-7 bond is saturated, the β isomer is some 50 times more potent than morphine.
Ro4-1539 (furethylnorlevorphanol) is an opioid analgesic drug from the morphinan series that was discovered by the pharmaceutical company Hoffmann–La Roche in the 1950s. It acts as a potent μ-opioid agonist, and was found to be around 30-60 times more potent than the related drug levorphanol in animal experiments. Although it has high potency, long duration, and good therapeutic index, Ro4-1539 had no particular clinical advantages over other available opioid drugs, and was never commercially marketed.
Racemorphan, or morphanol, is the racemic mixture of the two stereoisomers of 17-methylmorphinan-3-ol, each with differing pharmacology and effects:
Norlevorphanol is an opioid analgesic of the morphinan family that was never marketed. It is the levo-isomer of 3-hydroxymorphinan (morphinan-3-ol). Norlevorphanol is a Schedule I Narcotic controlled substance in the United States with an ACSCN of 9634 and in 2014 it had an annual aggregate manufacturing quota of 52 grams. It is used as the hydrobromide and hydrochloride (0.870).
N-Phenethylnormorphine is an opioid analgesic drug derived from morphine by replacing the N-methyl group with β-phenethyl. It is around eight to fourteen times more potent than morphine as a result of this modification, in contrast to most other N-substituted derivatives of morphine, which are substantially less active, or act as antagonists. Binding studies have helped to explain the increased potency of N-phenethylnormorphine, showing that the phenethyl group extends out to reach an additional binding point deeper inside the μ-opioid receptor cleft, analogous to the binding of the phenethyl group on fentanyl.
