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Other names | 3-methylfentanyl, Mefentanyl |
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Formula | C23H30N2O |
Molar mass | 350.506 g·mol−1 |
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Chirality | Racemic mixture |
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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, [1] depending on which isomer is used (with the cis isomers being the more potent ones). [2] [3]
3-methylfentanyl was first discovered in 1974 [4] and subsequently appeared on the street as an alternative to the clandestinely produced fentanyl analog α-methylfentanyl. However, it quickly became apparent that 3-methylfentanyl was much more potent than α-methylfentanyl, and correspondingly more dangerous. [5]
While 3-methylfentanyl was initially sold on the black market for only a short time between 1984 and 1985, its high potency made it an attractive target to clandestine drug producers, as racemic 3-MF is 10–15 times more potent than fentanyl, and so correspondingly larger amounts of cut product for street sales can be produced for an equivalent amount of effort as for producing fentanyl itself; one gram of 3-methylfentanyl might be sufficient to produce several thousand dosage units once diluted for sale. 3-MF has thus reappeared several times, at various places around the world. [6]
The only country in the world with significant (200+ deaths a year, more than 10,000 addicts) abuse of this chemical is Estonia, where a dose of 3-MF costs 10 €, and other opiates are not generally available since the end of the 2000s. [7] [8] Approximately 1100 deaths from fentanyl and 3-MF abuse were recorded in Estonia between 2005–2013, compared to approximately 450 deaths in Sweden, Germany, UK, Finland and Greece combined during the same period. [9]
Other opioid analogs even more potent still than 3-MF are known, such as carfentanil and ohmefentanyl, [10] but these are significantly more difficult to manufacture than 3-methylfentanyl. Since 2016 fentanyl seizures in Estonia contains mostly carfentanil or cyclopropylfentanyl. [11]
3-methylfentanyl has similar effects to fentanyl, but is far more potent due to increased binding affinity to its target site. Since fentanyl itself is already highly potent, 3-methylfentanyl is extremely dangerous when used recreationally, and has resulted in many deaths among recreational opioid users ingesting the drug. Side effects of fentanyl analogs are similar to those of fentanyl itself, which include itching, nausea and potentially serious respiratory depression, which can be life-threatening. Fentanyl analogs have killed hundreds of people throughout Europe and the former Soviet republics since the most recent resurgence in use began in Estonia in the early 2000s, and novel derivatives continue to appear. [9]
3-Methylfentanyl was also reported by media as the identity of the anaesthetic "gas" Kolokol-1 delivered as an aerosol [12] during the Moscow theater hostage crisis in 2002 in which many hostages died from accidental overdoses, 3-methylfentanyl was later ruled out as the primary agent used. The opiate antidote naloxone was on-hand to treat the victims of the crisis, but, whether due to their incarceration, lack of food, or water, or sleep, or due to the novel nature of the still-unconfirmed compound used, acute symptoms continued to develop, resulting in many fatalities despite the administration of naloxone.[ citation needed ]
A number of methods for synthesis have been published. The most recent is probably the method posted by the Serbian chemical society (2004). [13]
There is another method, though, for constructing the N-Benzyl-3-methyl-4-piperidone in a 2-stage Michael reaction, followed by Dieckmann cyclization as per usual.[ citation needed ]
Carfentanil or carfentanyl, sold under the brand name Wildnil, is an extremely potent opioid analgesic which is used in veterinary medicine to anesthetize large animals such as elephants and rhinoceroses. It is typically administered in this context by tranquilizer dart. Carfentanil has also been used in humans for imaging of 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.
Ohmefentanyl is an extremely potent opioid analgesic drug which selectively binds to the µ-opioid receptor.
α-Methylfentanyl an opioid analgesic that is an analog of fentanyl. It is sometimes sold as "China White".
Parafluorofentanyl is an opioid analgesic analogue of fentanyl developed by Janssen Pharmaceutica in the 1960s.
3-Methyl-thiofentanyl is an opioid analgesic and analogue of fentanyl.
Lofentanil 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.
3-Allylfentanyl is an opioid analgesic that is an analogue of fentanyl.
Phenaridine (2,5-dimethylfentanyl) is an opioid analgesic that is an analogue of fentanyl. It was developed in 1972, and is used for surgical anasthesia.
Mirfentanil is a fentanyl derivative with strong selectivity for the μ opioid receptor. At lower doses, it antagonizes the analgesic effects of alfentanil and substitutes for naloxone in morphine-treated monkeys; however, it also reverses naloxone-precipitated withdrawal in pigeons trained to discriminate morphine from naloxone.
Ocfentanil is a potent synthetic opioid structurally related to fentanyl that was developed in the early 1990s as one of a series of potent naloxone-reversible opioids in an attempt to obtain an opioid that had better therapeutic indices in terms of cardiovascular effects and respiratory depression as compared to fentanyl. Ocfentanil was never developed for medical use despite reasonable results in human clinical trials, but subsequently started to be sold as a designer drug starting in around 2013.
4-Phenylfentanyl is an opioid analgesic that is a derivative of fentanyl. It was developed during the course of research that ultimately resulted in super-potent opioid derivatives such as carfentanil, though it is a substantially less potent analogue. 4-Phenylfentanyl is around eight times the potency of fentanyl in analgesic tests on animals, but more complex 4-heteroaryl derivatives such as substituted thiophenes and thiazoles are more potent still, as they are closer bioisosteres to the 4-carbomethoxy group of carfentanil.
N-Methylnorcarfentanil (R-32395) is an opioid analgesic drug related to the highly potent animal tranquilizer carfentanil, but several thousand times weaker, being only slightly stronger than morphine. It was first synthesised by a team of chemists at Janssen Pharmaceutica led by Paul Janssen, who were investigating the structure-activity relationships of the fentanyl family of drugs. They found that replacing the phenethyl group attached to the piperidine nitrogen of fentanyl with a smaller methyl group, made it so much weaker that it was inactive as an analgesic in animals. However the same change made to the more potent analogue carfentanil retained reasonable opioid receptor activity, reflecting the higher binding affinity produced by the 4-carbomethoxy group.
Butyrfentanyl or butyrylfentanyl is a potent short-acting synthetic opioid analgesic drug. It is an analog of fentanyl with around one quarter of its potency. One of the first mentions of this drug can be found in document written by The College on Problem of Drug Dependence, where it is mentioned as N-butyramide fentanyl analog. This document also states that the article describing its clinical effects was published in 1987. It is an agonist for the μ-opioid receptors.
3-Methylbutyrfentanyl (3-MBF) is an opioid analgesic that is an analog of butyrfentanyl.
Acrylfentanyl (also known as acryloylfentanyl or Egyptenyl) is a highly potent opioid analgesic that is an analog of fentanyl and has been sold online as a designer drug. In animal studies the IC50 or half maximal inhibitory concentration for acrylfentanyl to displace naloxone is 1.4 nM, being slightly more potent than fentanyl itself (1.6 nM) as well as having a longer duration of action.
Methoxyacetylfentanyl, commonly known as MAF is an opioid analgesic that is an analog of fentanyl and has been sold online as a designer drug.
Tetrahydrofuranylfentanyl is an opioid analgesic that is an analog of fentanyl and has been sold online as a designer drug, first appearing in Europe in late 2016.
3-Phenylpropanoylfentanyl (β'-phenylfentanyl) is an opioid analgesic that is an analog of fentanyl, which was invented in 1981, and has been sold as a designer drug, first identified in March 2017 in Sweden.
Isofentanyl (3-methyl-benzylfentanyl) is an opioid analgesic that is an analog of fentanyl first invented in 1973, and which has been sold as a designer drug.