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Other names | Aminoxaphen; Aminoxafen; McN-742 |
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ECHA InfoCard | 100.164.420 |
Chemical and physical data | |
Formula | C9H10N2O |
Molar mass | 162.192 g·mol−1 |
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Chirality | Racemic mixture |
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Aminorex, sold under the brand names Menocil and Apiquel among others, is a weight loss (anorectic) stimulant drug. [2] [3] It was withdrawn from the market after it was found to cause pulmonary hypertension (PPH). [3] [4] In the United States, aminorex is a Schedule I controlled substance.
Aminorex, in the 2-amino-5-aryloxazoline group, was developed by McNeil Laboratories in 1962. [5] It is closely related to 4-methylaminorex (4-MAR). Aminorex has been shown to have locomotor-stimulant effects, lying midway between dextroamphetamine and methamphetamine. Aminorex effects have been attributed to the release of catecholamines. [6] It can be produced as a metabolite of the deworming medication levamisole, which is sometimes used as a cutting agent of illicitly produced cocaine. [7] [8]
Aminorex is a serotonin–norepinephrine–dopamine releasing agent (SNDRA). [9] [10] [11] Its EC50 values for induction of monoamine release are 26.4 nM for norepinephrine, 49.4 nM for dopamine, and 193 nM for serotonin. [9] [10] [11] In addition to its monoamine-releasing activity, aminorex is a weak agonist of the serotonin 5-HT2 receptors, including of the serotonin 5-HT2A, 5-HT2B, and 5-HT2C receptors. [10] Its EC50 values for activation of these receptors are 4,365 nM for 5-HT2A, 870 nM for 5-HT2B, and 525 nM for 5-HT2C. [10]
Compound | NE | DA | 5-HT | Ref |
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Phenethylamine | 10.9 | 39.5 | >10,000 | [12] [13] [14] |
Dextroamphetamine | 6.6–10.2 | 5.8–24.8 | 698–1,765 | [15] [16] [14] [17] |
Dextromethamphetamine | 12.3–14.3 | 8.5–40.4 | 736–1,292 | [15] [18] [14] [17] |
Aminorex | 15.1–26.4 | 9.1–49.4 | 193–414 | [15] [19] [14] [20] [17] |
cis-4-MAR | 4.8 | 1.7 | 53.2 | [20] [19] |
cis-4,4'-DMAR | 11.8–31.6 | 8.6–24.4 | 17.7–59.9 | [19] [21] [20] |
trans-4,4'-DMAR | 31.6 | 24.4 | 59.9 | [21] [20] |
cis-MDMAR | 14.8 | 10.2 | 43.9 | [21] |
trans-MDMAR | 38.9 | 36.2 | 73.4 | [21] |
Notes: The smaller the value, the more strongly the drug releases the neurotransmitter. The assays were done in rat brain synaptosomes and human potencies may be different. See also Monoamine releasing agent § Activity profiles for a larger table with more compounds. Refs: [22] [10] |
Activation of serotonin 5-HT2B receptors by aminorex, either directly via agonism or indirectly via serotonin release, has been implicated in the development of pulmonary arterial hypertension and cardiac valvulopathy with the drug. [10] [9] [23] [11] However, its EC50 for serotonin 5-HT2B receptor activation is 33-fold higher than its EC50 value for induction of norepinephrine release and is almost 50-fold less potent than the serotonin 5-HT2B receptor agonism of dexnorfenfluramine. [10] This seems to call into question the role of direct agonism of the serotonin 5-HT2B receptor in the toxicity of aminorex. [10] Along similar lines, chlorphentermine, a related drug that has also been associated with such adverse effects, shows negligible direct serotonin 5-HT2B receptor agonistic activity. [10] However, it is possible that metabolites of aminorex and chlorphentermine might be more potent in this action. [10]
Aminorex does not appear to have been assessed at the trace amine-associated receptor 1 (TAAR1). [24] [25] However, several derivatives of aminorex, such as 4-methylaminorex (4-MAR) and 4,4'-dimethylaminorex (4,4'-DMAR), have been found to be inactive at the mouse and rat TAAR1. [20] [26] [27] Many other monoamine releasing agents (MRAs), such as many amphetamines, are rodent and/or human TAAR1 agonists. [28] [29] Activation of the TAAR1 may auto-inhibit and thereby constrain the monoaminergic effects of these agents. [20] [26] [27] Lack of TAAR1 agonism in the case of aminorex analogues might enhance their effects relative to MRAs possessing TAAR1 agonism. [20] [26] [27]
Aminorex is a member of the 2-amino-5-phenyloxazoline group. [2] It is structurally related to the substituted amphetamines like amphetamine and to the substituted phenylmorpholines like phenmetrazine. [2]
A variety of derivatives and analogues of aminorex are known. [2] These include 2'-fluoro-4-methylaminorex (2F-MAR), 2C-B-aminorex, 3',4'-methylenedioxy-4-methylaminorex (MDMAR), 4'-bromo-4-methylaminorex (4B-MAR), 4'-chloro-4-methylaminorex (4C-MAR), 4'-fluoro-4-methylaminorex (4F-MAR), 4-methylaminorex (4-MAR), 4,4'-dimethylaminorex (4,4'-DMAR), clominorex, cyclazodone, fenozolone, fluminorex, pemoline, and thozalinone, among others. [2] [20] [27]
The synthesis was first reported in a structure-activity relationship study of 2-amino-5-aryl-2-oxazolines, where aminorex was found to be approximately 2.5 times more potent than D-amphetamine sulfate in inducing anorexia in rats, and was also reported to have CNS stimulant effects.
The racemic synthesis involves addition/cyclization reaction of 2-amino-1-phenylethanol with cyanogen bromide. [30] A similar synthesis has been also published. [31] In a search for a cheaper synthetic route, a German team developed an alternative route [32] which, by using chiral styrene oxide, allows an enantiopure product.
It was discovered in 1962 by Edward John Hurlburt, [33] and was quickly found in 1963 to have an anorectic effect in rats. It was introduced as a prescription appetite suppressant in Germany, Switzerland and Austria in 1965, but was withdrawn in 1972 after it was found to cause pulmonary hypertension in approximately 0.2% of patients, and was linked to a number of deaths. [6] [34]
Cathinone is a monoamine alkaloid found in the shrub Catha edulis (khat) and is chemically similar to ephedrine, cathine, methcathinone and other amphetamines. It is probably the main contributor to the stimulant effect of Catha edulis, also known as khat. Cathinone differs from many other amphetamines in that it has a ketone functional group. Other phenethylamines that share this structure include the stimulants methcathinone, MDPV, mephedrone and the antidepressant bupropion.
3,4-Methylenedioxyamphetamine (MDA), sometimes referred to as “sass,” is an empathogen-entactogen, stimulant, and psychedelic drug of the amphetamine family that is encountered mainly as a recreational drug. In its pharmacology, MDA is a serotonin–norepinephrine–dopamine releasing agent (SNDRA). In most countries, the drug is a controlled substance and its possession and sale are illegal.
Fenfluramine, sold under the brand name Fintepla, is a serotonergic medication used for the treatment of seizures associated with Dravet syndrome and Lennox–Gastaut syndrome. It was formerly used as an appetite suppressant in the treatment of obesity, but was discontinued for this use due to cardiovascular toxicity before being repurposed for new indications. Fenfluramine was used for weight loss both alone under the brand name Pondimin and in combination with phentermine commonly known as fen-phen.
Phentermine, sold under the brand name Adipex-P among others, is a medication used together with diet and exercise to treat obesity. It is available by itself or as the combination phentermine/topiramate. Phentermine is taken by mouth.
Phenmetrazine, sold under the brand name Preludin among others, is a stimulant drug first synthesized in 1952 and originally used as an appetite suppressant, but withdrawn from the market in the 1980s due to widespread misuse. It was initially replaced by its analogue phendimetrazine which functions as a prodrug to phenmetrazine, but now it is rarely prescribed, due to concerns of misuse and addiction. Chemically, phenmetrazine is a substituted amphetamine containing a morpholine ring or a substituted phenylmorpholine.
4-Methylaminorex is a stimulant drug of the 2-amino-5-aryloxazoline group that was first synthesized in 1960 by McNeil Laboratories. It is also known by its street name "U4Euh" ("Euphoria"). It is banned in many countries as a stimulant. 4-Methylaminorex has effects comparable to methamphetamine but with a longer duration.
Chlorphentermine, sold under the brand names Apsedon, Desopimon, and Lucofen, is a serotonergic appetite suppressant of the amphetamine family. Developed in 1962, it is the para-chloro derivative of the better-known appetite suppressant phentermine, which is still in current use.
Etilamfetamine, also known as N-ethylamphetamine and formerly sold under the brand names Apetinil and Adiparthrol, is a stimulant drug of the amphetamine family. It was invented in the early 20th century and was subsequently used as an anorectic or appetite suppressant in the 1950s, but was not as commonly used as other amphetamines such as amphetamine, methamphetamine, and benzphetamine, and was largely discontinued once newer drugs such as phenmetrazine were introduced.
Naphthylaminopropane, also known as naphthylisopropylamine (NIPA), is an experimental drug that was under investigation for the treatment of alcohol and stimulant addiction.
Norfenfluramine, or 3-trifluoromethylamphetamine, is a never-marketed drug of the amphetamine family and a major active metabolite of the appetite suppressants fenfluramine and benfluorex. The compound is a racemic mixture of two enantiomers with differing activities, dexnorfenfluramine and levonorfenfluramine.
para-Chloroamphetamine (PCA), also known as 4-chloroamphetamine (4-CA), is a serotonin–norepinephrine–dopamine releasing agent (SNDRA) and serotonergic neurotoxin of the amphetamine family. It is used in scientific research in the study of the serotonin system, as a serotonin releasing agent (SRA) at lower doses to produce serotonergic effects, and as a serotonergic neurotoxin at higher doses to produce long-lasting depletions of serotonin.
A monoamine releasing agent (MRA), or simply monoamine releaser, is a drug that induces the release of one or more monoamine neurotransmitters from the presynaptic neuron into the synapse, leading to an increase in the extracellular concentrations of the neurotransmitters and hence enhanced signaling by those neurotransmitters. The monoamine neurotransmitters include serotonin, norepinephrine, and dopamine; MRAs can induce the release of one or more of these neurotransmitters.
A serotonin releasing agent (SRA) is a type of drug that induces the release of serotonin into the neuronal synaptic cleft. A selective serotonin releasing agent (SSRA) is an SRA with less significant or no efficacy in producing neurotransmitter efflux at other types of monoamine neurons, including dopamine and norepinephrine neurons.
A dopamine releasing agent (DRA) is a type of drug which induces the release of dopamine in the body and/or brain.
Substituted cathinones, or simply cathinones, which include some stimulants and entactogens, are derivatives of cathinone. They feature a phenethylamine core with an alkyl group attached to the alpha carbon, and a ketone group attached to the beta carbon, along with additional substitutions. Cathinone occurs naturally in the plant khat whose leaves are chewed as a recreational drug.
4,4'-Dimethylaminorex, sometimes referred to by the street name "Serotoni", is a psychostimulant and entactogen designer drug related to aminorex, 4-methylaminorex, and pemoline. It was first detected in the Netherlands in December 2012, and has been sold as a designer drug around Europe since mid-2013.
3',4'-Methylenedioxy-4-methylaminorex (MDMAR) is a recreational designer drug from the substituted aminorex family, with monoamine-releasing effects. It is a potent serotonin–norepinephrine–dopamine releasing agent (SNDRA).
Substituted β-hydroxyamphetamines, or simply β-hydroxyamphetamines, also known as phenylisopropanolamines, phenylpropanolamines, norephedrines, or cathinols, are derivatives of β-hydroxyamphetamine with one or more chemical substituents. They are substituted phenethylamines, phenylethanolamines (β-hydroxyphenethylamines), and amphetamines (α-methylphenethylamines), and are closely related to but distinct from the substituted cathinones (β-ketoamphetamines). Examples of β-hydroxyamphetamines include the β-hydroxyamphetamine stereoisomers phenylpropanolamine and cathine and the stereospecific N-methylated β-hydroxyamphetamine derivatives ephedrine and pseudoephedrine, among many others.
2-Phenylmorpholine is the parent compound of the substituted phenylmorpholine class of compounds. Examples of 2-phenylmorpholine derivatives include phenmetrazine (3-methyl-2-phenylmorpholine), phendimetrazine ( -3,4-dimethyl-2-phenylmorpholine), and pseudophenmetrazine ( -3-methyl-2-phenylmorpholine), which are monoamine releasing agents (MRAs) and psychostimulants. 2-Phenylmorpholine itself is a potent norepinephrine–dopamine releasing agent (NDRA) and hence may act as a stimulant similarly.
RESULTS. Methamphetamine and amphetamine potently released NE (IC50s = 14.3 and 7.0 nM) and DA (IC50s = 40.4 nM and 24.8 nM), and were much less potent releasers of 5-HT (IC50s = 740 nM and 1765 nM). Phentermine released all three biogenic amines with an order of potency NE (IC50 = 28.8 nM)> DA (IC50 = 262 nM)> 5-HT (IC50 = 2575 nM). Aminorex released NE (IC50 = 26.4 nM), DA (IC50 = 44.8 nM) and 5-HT (IC50 = 193 nM). Chlorphentermine was a very potent 5-HT releaser (IC50 = 18.2 nM), a weaker DA releaser (IC50 = 935 nM) and inactive in the NE release assay. Chlorphentermine was a moderate potency inhibitor of [3H]NE uptake (Ki = 451 nM). Diethylpropion, which is self-administered, was a weak DA uptake inhibitor (Ki = 15 µM) and NE uptake inhibitor (Ki = 18.1 µM) and essentially inactive in the other assays. Phendimetrazine, which is self-administered, was a weak DA uptake inhibitor (IC50 = 19 µM), a weak NE uptake inhibitor (8.3 µM) and essentially inactive in the other assays.
Due to the lack of interaction with the trace amine-associated receptor 1 (TAAR1), 4,4'- DMAR is suspected to be unable to trigger the auto-inhibitory pathway that, for example, MDMA possesses at least in rodents135,183,184. [...] As mentioned before, in contrast to other amphetamine-type stimulants, 4,4'-DMAR does not interact with TAAR1 and therefore lacks the auto-inhibitory pathway that attenuates monoamine release and mediates the neuroprotective effects231,232. It has however been shown that many psychoactive compounds stimulate human TAAR1 less potently than the receptor's rodent counterparts184.
Receptor-binding experiments suggest that 4,4'-DMAR exhibits no – or if at all only poor-affinity towards mouse and rat TAAR1. On the contrary, sub- (rat) and low-micromolar (mouse) affinities towards TAAR1 have been reported for MDMA (Simmler et al., 2013). The exact role of TAAR1 in amphetamine action remains far from being completely understood (Sitte and Freissmuth, 2015). However, TAAR1 appears to exert auto-inhibitory effects on monoaminergic neurons, thus regulates the release of the corresponding monoamines (Revel et al., 2011, 2012). TAAR1 is activated by a subset of amphetamines (Simmler et al., 2016). This observation has been linked to auto-inhibitory and neuroprotective effects of TAAR1 in amphetamine action (Miner et al., 2017; Revel et al., 2012; DiCara et al., 2011; Lindemann et al., 2008). The lack of agonist activity at TAAR1 might further contribute to long-term toxicity of 4,4'-DMAR, thus representing an interesting field for future investigations.
The methylated aminorex derivatives investigated in the present study did not interacted with TAAR1 receptors in contrast to amphetamine, MDMA, and several other phenethylamine derivatives (Revel et al., 2012; Simmler et al., 2016). Other aminorex-like ring-substituted 2- aminooxazolines have been shown to interact with TAAR1 receptors (Galley et al., 2016). However, they did not contain a 4-methyl group in contrast to the currently investigated compounds. Activity at TAAR1 may have auto-inhibitory effects on the monoaminergic action of amphetamine-type substances (Di Cara et al., 2011; Simmler et al., 2016). Therefore, the presently investigated compounds that did not bind to TAAR1 may exhibit greater stimulant properties compared to other amphetamines that also bind to TAAR1.