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 is an analgesic drug, 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.
Levomethorphan (LVM) 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.
Metopon (5-methylhydromorphone) is an opioid analogue that is a methylated derivative of hydromorphone which was invented in 1929 as an analgesic.
Ohmefentanyl is an extremely potent opioid analgesic drug which selectively binds to the µ-opioid receptor.
7-PET is an opioid analgesic drug that has 300 times the potency of morphine by weight. It was discovered by K.W. Bentley and is related to the more well known oripavine derivative etorphine, which is used as a veterinary painkiller and anesthetic medication for the sedation of large animals such as elephants, giraffes, and rhinos. 7-PET itself has a 3-O-methyl ether which reduces potency, but the 3-OH derivative is around 2200 times more potent than morphine, almost the same potency as etorphine as a μ agonist, and unexpectedly the 3-hydrogen compound is also around the same potency of 2000 times morphine.
Metofoline (INN), also known as methofoline (USAN), is an opioid analgesic drug discovered in the 1950s by a team of Swiss researchers at Hoffmann-La Roche.
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.
14-Phenylpropoxymetopon (PPOM) is an opiate 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.
N-Phenethyl-14-ethoxymetopon is a drug that is a derivative of metopon. It is a potent analgesic, around 60 times stronger than morphine and produces significantly less constipation.
Conorfone, also known as conorphone and codorphone, as well as conorphone hydrochloride (USAN), is an opioid analgesic that was never marketed. It is an analogue of hydrocodone substituted with an 8-ethyl group and an N-cyclopropylmethyl group. It acts as a mixed agonist-antagonist at the μ-opioid receptor, and is slightly more potent than codeine in analgesic effects but associated with somewhat greater side effects.
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.
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.
Proxorphan (INN), also known as proxorphan tartate (USAN), is an opioid analgesic and antitussive drug of the morphinan family that was never marketed. It acts preferentially as a κ-opioid receptor partial agonist and to a lesser extent as a μ-opioid receptor partial agonist.
8-Carboxamidocyclazocine (8-CAC) is an opioid analgesic drug related to cyclazocine, discovered by medicinal chemist Mark P. Wentland and co-workers in Cogswell Laboratory at Rensselaer Polytechnic Institute. Similarly to cyclazocine, 8-CAC acts as an agonist at both the μ and κ opioid receptors, but has a much longer duration of action than cyclazocine, and does not have μ antagonist activity. Unexpectedly it was discovered that the phenolic hydroxyl group of cyclazocine could be replaced by a carboxamido group with only slight loss of potency at opioid receptors, and this discovery has subsequently been used to develop many novel opioid derivatives where the phenolic hydroxy group has been replaced by either carboxamide or a variety of larger groups. Due to their strong κ-opioid agonist activity, these drugs are not suited for use as analgesics in humans, but have instead been researched as potential drugs for the treatment of cocaine addiction.
N-Phenethylnordesomorphine is an opiate analgesic drug derived from desomorphine by replacing the N-methyl group with β-phenethyl. Since desomorphine is already around eight times more potent than morphine, the additional boost in binding affinity produced by using the larger phenethyl group makes N-phenethylnordesomorphine a highly potent analgesic drug, some 85x more potent than morphine, and a similar strength to the closely related morphinan derivative phenomorphan.
Ketorfanol, or ketorphanol, is an opioid analgesic of the morphinan family that was found to possess "potent antiwrithing activity" in animal assays but was never marketed. It is a 17-cycloalkylmethyl derivative of morphinan and as such, is closely related structurally to butorphanol, cyclorphan, oxilorphan, proxorphan, and xorphanol, which act preferentially as κ-opioid receptor agonists and to a lesser extent as μ-opioid receptor partial agonists/antagonists.
