Nalbuphine, sold under the brand names Nubain among others, is an opioid analgesic which is used in the treatment of pain. It is given by injection into a vein, muscle, or fat.
Ohmefentanyl is an extremely potent opioid analgesic drug which selectively binds to the µ-opioid receptor.
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.
Lofentanil or lofentanyl is one of the most potent opioid analgesics known and is an analogue of fentanyl, which was developed in 1960. It is most similar to the highly potent opioid carfentanil (4-carbomethoxyfentanyl), only slightly more potent. Lofentanil can be described as 3-methylcarfentanil, or 3-methyl-4-carbomethoxyfentanyl. While 3-methylfentanyl is considerably more potent than fentanyl itself, lofentanil is only slightly stronger than carfentanil. This suggests that substitution at both the 3 and 4 positions of the piperidine ring introduces steric hindrance which prevents μ-opioid affinity from increasing much further. As with other 3-substituted fentanyl derivatives such as ohmefentanyl, the stereoisomerism of lofentanil is very important, with some stereoisomers being much more potent than others.
Oripavine is an opioid and the major metabolite of thebaine. It is the parent compound from which a series of semi-synthetic opioids are derived, which includes the compounds etorphine and buprenorphine. Although its analgesic potency is comparable to morphine, it is not used clinically due to its severe toxicity and low therapeutic index. Due to its use in manufacture of strong opioids, oripavine is a controlled substance in some jurisdictions.
Dezocine, sold under the brand name Dalgan, is an atypical opioid analgesic which is used in the treatment of pain. It is used by intravenous infusion and intramuscular injection.
Cyprenorphine (M285), N-cyclo-propylmethyl-6,14-endoetheno-7α-(1-hydroxy-1-methylethyl)-6,7,8,14-tetrahydronororipavine, is an opioid drug. It is related to more well-known opioids such as buprenorphine, which is used as an analgesic and for the treatment of opioid addiction, and diprenorphine, which is used as an antidote to reverse the effects of other opioids. It is roughly 35 times as strong as nalorphine.
SNC-80 is an opioid analgesic compound that selectively activates μ–δ opioid receptor heteromers and is used in scientific research. It was discovered in 1994.
Viminol is an opioid analgesic developed by a team at the drug company Zambon in the 1960s. Viminol is based on the α-pyrryl-2-aminoethanol structure, unlike any other class of opioids.
14-Methoxymetopon is an experimental opioid drug developed by a team led by Professor Helmut Schmidhammer at the University of Innsbruck in the mid-1990s. It is a derivative of metopon in which a methoxy group has been inserted at the 14-position. It is a highly potent analgesic drug that is around 500 times stronger than morphine when administered systemically; however, when given spinally or supraspinally, it exhibits analgesic activity up to a million fold greater than morphine. It binds strongly to the μ-opioid receptor and activates it to a greater extent than most similar opioid drugs. This produces an unusual pharmacological profile, and although 14-methoxymetopon acts as a potent μ-opioid full agonist in regard to some effects such as analgesia, a ceiling effect is seen on other effects such as constipation and respiratory depression which is believed to involve interaction with the κ-opioid receptor
BU-48 is a drug that is used in scientific research. It is from the oripavine family, related to better-known drugs such as etorphine and buprenorphine.
Xorphanol (INN), also known as xorphanol mesylate (USAN), is an opioid analgesic of the morphinan family that was never marketed.
In pharmacology the term agonist-antagonist or mixed agonist/antagonist is used to refer to a drug which under some conditions behaves as an agonist while under other conditions, behaves as an antagonist.
Alazocine, also known more commonly as N-allylnormetazocine (NANM), is a synthetic opioid analgesic of the benzomorphan family related to metazocine, which was never marketed. In addition to its opioid activity, the drug is a sigma receptor agonist, and has been used widely in scientific research in studies of this receptor. Alazocine is described as a potent analgesic, psychotomimetic or hallucinogen, and opioid antagonist. Moreover, one of its enantiomers was the first compound that was found to selectively label the σ1 receptor, and led to the discovery and characterization of the receptor.
GR-89696 is a drug which acts as a highly selective κ-opioid agonist. It has been studied in various animal species, and has been described as selective for the κ2 subtype. Recent studies have suggested that GR-89696 and related κ2-selective agonists may be useful for preventing the itching which is a common side effect of conventional opioid analgesic drugs, without the additional side effects of non-selective kappa agonists. The structure bound to the κ-opioid receptor has been reported.
MT-45 (IC-6) is an opioid analgesic drug invented in the 1970s by Dainippon Pharmaceutical Co. It is chemically a 1-substituted-4-(1,2-diphenylethyl) piperazine derivative, which is structurally unrelated to most other opioid drugs. Racemic MT-45 has around 80% the potency of morphine, with almost all opioid activity residing in the (S) enantiomer. It has been used as a lead compound from which a large family of potent opioid drugs have been developed, including full agonists, partial agonists, and antagonists at the three main opioid receptor subtypes. Fluorinated derivatives of MT-45 such as 2F-MT-45 are significantly more potent as μ-opioid receptor agonists, and one of its main metabolites 1,2-diphenylethylpiperazine also blocks NMDA receptors.
AD-1211 is an opioid analgesic drug invented in the 1970s by Dainippon Pharmaceutical Co. It is chemically a 1-substituted-4-prenyl-piperazine derivative, which is structurally unrelated to most other opioid drugs. The (S)-enantiomers in this series are more active as opioid agonists, but the less active (R)-enantiomer of this compound, AD-1211, is a mixed agonist–antagonist at opioid receptors with a similar pharmacological profile to pentazocine, and has atypical opioid effects with little development of tolerance or dependence seen after extended administration in animal studies.
Thienorphine is a very potent, extremely long-acting, orally-active opioid analgesic with mixed agonist–antagonist properties which was developed by the Beijing Institute of Pharmacology and Toxicology as a potential treatment for opioid dependence. It is a high-affinity, balanced ligand of the μ-, δ-, and κ-opioid receptors, behaving as a partial agonist of the μ- and κ-opioid receptors and as an antagonist of the δ-opioid receptor. It also possesses relatively low affinity for the nociceptin receptor, where it acts as an antagonist.
Utopioids are a class of synthetic opioid analgesic drugs first developed in the 1970s by the pharmaceutical company Upjohn. However, they were never marketed for medical use. Some compounds from this class have been used for scientific research as model kappa opioid receptor agonists. In the mid-2010s, one mu opioid receptor selective compound from this class, U-47700, re-emerged as a designer drug and became widely sold around the world for several years before being banned in various jurisdictions from 2016 onwards. Following the prohibition of U-47700, a number of related compounds have continued to appear on illicit drug markets. They are often marketed online or included as components in mixtures sold under the guise of "street heroin." U-47700 itself is the most potent mu opioid agonist from this class, around 7-10x the potency of morphine. Some other compounds such as 3,4-MDO-U-47700 and N-Ethyl-U-47700 retain similar mu selectivity but with lower potency similar to that of morphine, or have a mixture of mu and kappa mediated effects, such as U-48800. Most utopioid derivatives are however selective kappa agonists, which may have limited abuse potential as dissociative hallucinogens, but do not alleviate withdrawal distress in opioid dependent individuals or maintain addiction in a typical sense. Nevertheless, this has not stopped them from being sold as designer drugs, and a number of these compounds are now banned in many jurisdictions alongside U-47700 itself.
Ro65-6570 is an opioid drug. It has a potential use in preventing the addiction to other opioids.
