Synthetic opioids

Fentanyl is a highly potent synthetic opioid of the piperidine family, used primarily as pain medication. It is 50 to 100 times more potent than morphine. Its primary clinical use is in pain management for cancer patients and those recovering from surgery. Fentanyl is also used as a sedative for intubated patients. Fentanyl has a short duration of action. Fentanyl works by activating μ-opioid receptors. Brand names include Actiq, Duragesic, and Sublimaze, among others.

Methadone, sold under the brand names Dolophine and Methadose among others, is a potent synthetic opioid used medically to treat chronic pain and opioid use disorder. Prescribed for daily use, the medicine relieves cravings and opioid withdrawal symptoms. Withdrawal management using methadone can be accomplished in less than a month, or it may be done gradually over a longer period of time, or simply maintained for the rest of the patient's life. While a single dose has a rapid effect, maximum effect can take up to five days of use. After long-term use, in people with normal liver function, ef

Pethidine, also known as meperidine and sold under the brand name Demerol among others, is a fully synthetic opioid pain medication of the phenylpiperidine class. Synthesized in 1938 as a potential anticholinergic agent by the German chemist Otto Eisleb, its analgesic properties were first recognized by Otto Schaumann while working for IG Farben, in Germany. Pethidine is the prototype of a large family of analgesics including the pethidine 4-phenylpiperidines (e.g., piminodine, anileridine), the prodines (e.g., alphaprodine, MPPP), bemidones (e.g., ketobemidone), and others more distant, inclu

Loperamide, sold under the brand name Imodium, among others, is a medication of the opioid receptor agonist class used to decrease the frequency of diarrhea. It is often used for this purpose in irritable bowel syndrome, inflammatory bowel disease, short bowel syndrome, Crohn's disease, and ulcerative colitis. Loperamide is taken by mouth.

Tianeptine, sold under the brand names Stablon, Tatinol, and Coaxil among others, is an atypical tricyclic antidepressant which is used mainly in the treatment of major depressive disorder, although it may also be used to treat anxiety, asthma, and irritable bowel syndrome.

Pentazocine, sold under the brand name Talwin among others, is an analgesic medication used to treat moderate to severe pain. It is believed to work by activating (agonizing) κ-opioid receptors (KOR) and μ-opioid receptors (MOR). As such it is called an opioid as it delivers its effects on pain by interacting with the opioid receptors. It shares many of the side effects of other opioids like constipation, nausea, itching, drowsiness, and respiratory depression, but, unlike most other opioids, it fairly frequently causes hallucinations, nightmares, and delusions. It is also, unlike most other o

Dextropropoxyphene is an opioid analgesic patented in 1955 and manufactured by Eli Lilly and Company. It is an optical isomer of levopropoxyphene. It is intended to treat mild pain and also has antitussive (cough suppressant) and local anesthetic effects. The drug has been taken off the market in Europe and the United States due to concerns of fatal overdoses and heart arrhythmias. It is still available in Australia, albeit with restrictions after an application by its manufacturer to review its proposed banning. Its onset of analgesia (pain relief) is said to be 20–30 minutes and peak effects

Alfentanil, sold under the brand name Alfenta among others, is a potent, short-acting synthetic opioid analgesic drug used for anesthesia in surgery. It is an analogue of fentanyl with around one-fourth to one-tenth the potency, one-third the duration of action, and an onset of action four times faster than that of fentanyl. Alfentanil has a pKa of approximately 6.5, which leads to a very high proportion of the drug being uncharged at physiologic pH, a characteristic responsible for its rapid-onset. It is an agonist of the μ-opioid receptor.

Carfentanil or carfentanyl, formerly sold under the brand name Wildnil, is an extremely potent opioid analgesic used in veterinary medicine to anesthetize large animals such as elephants and rhinoceroses. It is a structural analogue of the synthetic opioid analgesic fentanyl. It is typically administered in this context by tranquilizer dart. Carfentanil has also been used in humans to image opioid receptors. It has additionally been used as a recreational drug, typically by injection, insufflation, or inhalation. Deaths have been reported in association with carfentanil.

Levorphanol (brand name Levo-Dromoran) 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.

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.

Anileridine (trade name: Leritine) is a synthetic analgesic drug and is a member of the piperidine class of analgesic agents developed by Merck & Co. in the 1950s. It differs from pethidine (meperidine) in that the N-methyl group of meperidine is replaced by an N-aminophenethyl group, which increases its analgesic activity.

Diphenoxylate is a centrally active opioid drug of the phenylpiperidine series that is used as a combination drug with atropine for the treatment of diarrhea. Diphenoxylate is an opioid and acts by slowing intestinal contractions; the atropine is present to prevent drug abuse and overdose. It should not be given to children due to the risk that they will stop breathing and should not be used in people with Clostridioides difficile infection.

Ketobemidone, sold under the brand name Ketogan (a mixture of ketobemidone and Spasmolytic A29) among others, is a powerful synthetic opioid painkiller. Its effectiveness against pain is in the same range as morphine, and it also has some NMDA-antagonist properties imparted, in part, by its metabolite norketobemidone. This may make it useful for some types of pain that do not respond well to other opioids. It is marketed in Denmark, Iceland, Norway. Until 2024 it was available in, but is now withdrawn in Sweden. It is used for severe pain.

Meptazinol, sold under the brand name Meptid, is an opioid analgesic developed by Wyeth in the 1970s. Indications for use in moderate to severe pain, most commonly used to treat pain in obstetrics (childbirth).

Dextromoramide (Palfium, Palphium, Jetrium, Dimorlin) is a powerful opioid analgesic approximately three times more potent than morphine but shorter acting. It is subject to drug prohibition regimes, both internationally through UN treaties and by the criminal law of individual nations, and is usually prescribed only in the Netherlands.

Desmethylprodine or 1-methyl-4-phenyl-4-propionoxypiperidine (MPPP, Ro 2-0718) is an opioid analgesic drug developed in the 1940s by researchers at Hoffmann-La Roche. Desmethylprodine has been labeled by the DEA as a Schedule I drug in the United States. It is an analog of pethidine (meperidine) a Schedule II drug. Chemically, it is a reversed ester of pethidine which has about 70% of the potency of morphine. Unlike its derivative prodine, it does not exhibit optical isomerism. It was reported to have 30 times the activity of pethidine and a greater analgesic effect than morphine in rats, and

Trimeperidine (trade name Promedol) is an opioid analgesic that is an analogue of prodine. It was developed in the early 1950s in the USSR during research into the related drug pethidine.

Naloxegol (INN; PEGylated naloxol; trade names Movantik and Moventig) is a peripherally acting μ-opioid receptor antagonist developed by AstraZeneca, licensed from Nektar Therapeutics, for the treatment of opioid-induced constipation. It was approved in 2014 in adult patients with chronic, non-cancer pain. Doses of 25 mg were found safe and well tolerated for 52 weeks. When given concomitantly with opioid analgesics, naloxegol reduced constipation-related side effects, while maintaining comparable levels of analgesia.

Allylprodine is an opioid analgesic that is an analog of prodine. It was discovered by Hoffman-La Roche in 1957 during research into the related drug pethidine. Derivatives were tested to prove the theory that phenolic and non-phenolic opioids bind at different sites of the opiate receptor.

Bezitramide is an opioid analgesic. Bezitramide itself is a prodrug which is readily hydrolyzed in the gastrointestinal tract to its active metabolite, despropionyl-bezitramide. Bezitramide was discovered at Janssen Pharmaceutica in 1961. It is most commonly marketed under the trade name Burgodin.

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

Difenoxin (Motofen, R-15403) is an opioid drug used, often in combination with atropine, to treat diarrhea. It is the principal metabolite of diphenoxylate.

Phenazocine (brand names Prinadol, Narphen) is an opioid analgesic drug, which is related to pentazocine and has a similar profile of effects.

3-Methylfentanyl (3-MF, mefentanyl) is an opioid analgesic that is an analog of fentanyl. 3-Methylfentanyl is one of the most potent opioids, estimated to be between 400 and 6000 times stronger than morphine, depending on which isomer is used (with the cis isomers being the more potent ones).

Dipipanone, sold under the brand names of Pipadone and Diconal is a strong opioid analgesic drug, used for acute pain by mouth (PO) for adults. It is often used in instances where morphine is indicated but cannot be used due to the patient being allergic to morphine. In analgesic potency 25 mg dipipanone is approximately equivalent to 10 mg morphine.

Benzethidine is a 4-phenylpiperidine derivative that is related to the clinically used opioid analgesic drug pethidine (meperidine, or Demerol).

Levacetylmethadol (INN), levomethadyl acetate (USAN), OrLAAM (trade name) or levo-α-acetylmethadol (LAAM) is a synthetic opioid similar in structure to methadone. It has a long duration of action due to its active metabolites.

Alphacetylmethadol (INN), or α-acetylmethadol (AAM), is a synthetic opioid analgesic. Its levorotary enantiomer, levacetylmethadol, is an FDA-approved treatment for opioid addiction; however as of 2003 it is no longer used in the United States for this purpose. Alphacetylmethadol is very similar in structure to methadone, a widely prescribed treatment for opioid addiction. In the United States, it is a Schedule I controlled substance under the Controlled Substances Act (presumably because it was never marketed in the US, as is the case with other common opiate/opioid medications such as heroin

Ohmefentanyl (also known as β-hydroxy-3-methylfentanyl, OMF and RTI-4614-4) is an extremely potent opioid analgesic drug which selectively binds to the μ-opioid receptor.

Phenomorphan is an opioid analgesic. It is not currently used in medicine, but has similar side-effects to other opiates, which include itching, nausea and respiratory depression.

α-Methylthiofentanyl is an opioid analgesic that is an analogue of fentanyl.

Levopropoxyphene is an antitussive. It is an optical isomer of dextropropoxyphene. The racemic mixture is called propoxyphene. Only the dextro-isomer (dextropropoxyphene) has an analgesic effect; the levo-isomer appears to exert only an antitussive effect. It was formerly marketed in the U.S. by Eli Lilly under the tradename Novrad (a reversal of Darvon) as an antitussive. Unlike many antitussives, it binds poorly to the sigma-1 receptor.

Etoxeridine (Carbetidine, Atenos) is a 4-phenylpiperidine derivative that is related to the clinically used opioid analgesic drug pethidine (meperidine).

Normethadone (INN, BAN; brand names Ticarda, Cophylac, Dacartil, Eucopon, Mepidon, Noramidone, Normedon, and others), also known as desmethylmethadone or phenyldimazone, is a synthetic opioid analgesic and antitussive agent. Normethadone is listed under the Single Convention on Narcotic Drugs 1961 and is a Schedule I Narcotic controlled substance in the United States, with a DEA ACSCN of 9635 and an annual manufacturing quota of 2 grams. The salts in use are the hydrobromide (free base conversion ratio 0.785), hydrochloride (0.890), methyliodide (0.675), oxalate (0.766), picrate (0.563), and t

Phenadoxone (trade names Heptalgin, Morphidone, and Heptazone) is an opioid analgesic of the open chain class (methadone and relatives) invented in Germany by Hoechst in 1947. It is one of a handful of useful synthetic analgesics which were used in the United States for various lengths of time in the 20 or so years after the end of the Second World War but which were withdrawn from the market for various or no known reason and which now are mostly in Schedule I of the United States' Controlled Substances Act of 1970, or (like phenazocine and bezitramide) in Schedule II but not produced or mark

Desmetramadol (), also known as '''O-desmethyltramadol (O-DSMT'''), is an opioid analgesic and the main active metabolite of tramadol. Tramadol is demethylated by the liver enzyme CYP2D6 to desmetramadol in the same way as codeine, and so similarly to the variation in effects seen with codeine, individuals who have a less active form of CYP2D6 will tend to have reduced analgesic effects from tramadol. Because desmetramadol itself does not need to be metabolized to induce an analgesic effect, it can be used in individuals with CYP2D6 inactivating mutations.

Diethylthiambutene (Thiambutene, Themalon, Diethibutin, N,N-Diethyl-1-methyl-3,3-di-2-thienylallylamine) is an opioid analgesic drug developed in the 1950s which was mainly used as an anesthetic in veterinary medicine and continues, along with the other two thiambutenes dimethylthiambutene and ethylmethylthiambutene to be used for this purpose, particularly in Japan. It is now under international control under Schedule I of the UN Single Convention On Narcotic Drugs 1961, presumably due to high abuse potential, although little more information is available. It is listed under Schedule I of the

Acetylmethadol, also known as methadyl acetate, is a synthetic opioid analgesic. It is a racemic mixture of alphacetylmethadol (α-acetylmethadol) and betacetylmethadol (β-acetylmethadol), which are in turn racemic mixtures of levacetylmethadol (LAAM; L-α-acetylmethadol) and D-α-acetylmethadol and L-β-acetylmethadol and D-β-acetylmethadol, respectively. Hence, acetylmethadol has four possible optical isomers. All of these isomers have been shown to partially or fully substitute for the discriminative stimulus effects of heroin in rats, and thus it can be inferred that, in addition to LAAM which

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 (where it is a high-efficacy agonist) and/or sigma receptors.

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.

Morpheridine (Morpholinoethylnorpethidine) is a 4-phenylpiperidine derivative that is related to the clinically used opioid analgesic drug pethidine (meperidine). It is a strong analgesic with around 4 times the potency of pethidine, and unlike pethidine, does not cause convulsions, although it produces the standard opioid side effects such as sedation and respiratory depression.

Levallorphan (INN, BAN; USAN levallorphan tartrate; brand names Lorfan, Naloxifan, and Naloxiphan) is an opioid modulator of the morphinan family used as an opioid analgesic and opioid antagonist/antidote. It acts as an antagonist of the μ-opioid receptor (MOR) and as an agonist of the κ-opioid receptor (KOR), and as a result, blocks the effects of stronger agents with greater intrinsic activity such as morphine whilst simultaneously producing analgesia.

Diampromide is an opioid analgesic from the ampromide family of drugs, related to other drugs such as propiram and phenampromide. It was invented in the 1960s by American Cyanamid, and can be described as a ring-opened analogue of fentanyl.

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 (free base conversion ratio 0.750) and hydrochloride (0.870). It has morphine-like pharmacological properties.

Alphamethadol (INN), or α-methadol, also known as alfametadol, is a synthetic opioid analgesic. It is an isomer of dimepheptanol (methadol), the other being betamethadol (β-methadol). Alphamethadol is composed of two isomers itself, L-α-methadol, and D-α-methadol. Both of alphamethadol's isomers bind to and activate the μ-opioid receptor and are active as opioid analgesics, similarly to those of alphacetylmethadol (α-acetylmethadol).

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 (table VII).

Acetylfentanyl (acetyl fentanyl) is an opioid analgesic drug that is an analog of fentanyl. Studies have estimated acetylfentanyl to be 15 times more potent than morphine, which would mean that despite being somewhat weaker than fentanyl, it is nevertheless still several times stronger than pure heroin. It has never been licensed for medical use and instead has only been sold on the illicit drug market. Acetylfentanyl was discovered at the same time as fentanyl itself and had only rarely been encountered on the illicit market in the late 1980s. However, in 2013, Canadian police seized 3 kilogr

Betamethadol (INN), or β-methadol, also known as betametadol, is a synthetic opioid analgesic. It is an isomer of dimepheptanol (methadol), the other being alphamethadol (α-methadol). Betamethadol is composed of two isomers itself, L-β-methadol, and D-β-methadol. Based on structure-activity relationships it can be inferred that both isomers are likely to be active as opioid analgesics, similarly to those of betacetylmethadol (β-acetylmethadol).

Dimethylthiambutene (N,N-Dimethyl-1-methyl-3,3-di-2-thienylallylamine, DMTB, trade names Ohton, Aminobutene, Dimethibutin, Kobaton, Takaton, Dimethibutin) is an opioid analgesic drug, most often used in veterinary medicine in Japan and to a lesser extent in other countries in the region and around the world. It is the most prominent and widely used of the thiambutenes, a series of open-chain opioids structurally related to methadone which are also called the thienyl derivative opioids which also includes diethylthiambutene and ethylmethylthiambutene, as well as the non-opioid cough suppressant

Norpethidine (normeperidine, pethidine intermediate B) is a 4-phenylpiperidine derivative that is both a precursor to, and the toxic metabolite of, pethidine (meperidine). It is scheduled by UN Single Convention on Narcotic Drugs. It is a Schedule II Narcotic controlled substance in the United States and has an ACSCN of 9233. The 2014 annual manufacturing quota was .

β-Hydroxyfentanyl is an opioid analgesic that is an analogue of fentanyl.

Dimenoxadol (INN; also known as dimenoxadole (BAN) or dimenoxadole; brand name Estocin in Russia) is an opioid analgesic which is a benzilic acid derivative, closely related to benactyzine (an anticholinergic). Further, the structure is similar to methadone and related compounds like dextropropoxyphene.

3-Methylthiofentanyl is an opioid analgesic and analogue of fentanyl.

Hydroxypethidine (Bemidone) is an opioid analgesic that is an analogue of the more commonly used pethidine (meperidine). Hydroxypethidine is slightly more potent than meperidine as an analgesic, 1.5x meperidine in potency, and it also has NMDA antagonist properties like its close relative ketobemidone.

Samidorphan (, ) is an opioid antagonist that in the form of olanzapine/samidorphan (sold as Lybalvi) is used in the treatment of schizophrenia and bipolar disorder. Samidorphan reduces the weight gain associated with olanzapine. Samidorphan is taken by mouth.

AH-7921 (Doxylam) is an opioid analgesic drug selective for the μ-opioid receptor, having around 90% the potency of morphine when administered orally. It was discovered in the 1970s by a team at Allen and Hanburys located in the United Kingdom. The drug is considered a new psychoactive substance (NPS), a designation of compounds designed to mimic the effects controlled substances. It has also been sold on the internet since 2012 as a "research chemical". When sold online it may be called the alternative name doxylam, not to be confused with doxylamine. AH-7921 has never progressed to clinical

Cyclazocine is a mixed opioid agonist/antagonist related to dezocine, pentazocine and phenazocine. It is in the benzomorphan and benzazocine family of drugs. It is a κ-opioid receptor agonist and μ-opioid receptor partial agonist, and also has high affinity for the δ-opioid receptor.

Dimepheptanol (INN; Amidol, Pangerin), also known as methadol or racemethadol, is a synthetic opioid analgesic related to methadone. It has similar effects to other opioids, including analgesia, sedation and euphoria, as well as side effects like itching, nausea and respiratory depression.

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