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Other names | 4-Chlorophentermine; 4-Chloro-α-methylamphetamine; 4-Chloro-α,α-dimethylphenethylamine |
Routes of administration | Oral |
Drug class | Serotonin releasing agent; Selective serotonin releasing agent; Appetite suppressant; Anorectic; Anorexic; Anorexiant |
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Elimination half-life | 40 hours [2] –5 days [3] |
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ECHA InfoCard | 100.006.651 |
Chemical and physical data | |
Formula | C10H14ClN |
Molar mass | 183.68 g·mol−1 |
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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.
The drug acts as a highly selective serotonin releasing agent (SRA). [4] It is not a psychostimulant and has little or no misuse potential, but is classed as a Schedule III drug in the United States due mainly to its similarity to other appetite suppressants such as diethylpropion which have been more widely misused. It is no longer used due mainly to safety concerns, as it has a serotonergic effects profile similar to other withdrawn appetite suppressants such as fenfluramine and aminorex which were found to cause pulmonary hypertension and cardiac fibrosis following prolonged use. [5]
Chlorphentermine was first synthesized by 1954 and was subsequently developed in the early 1960s. [6] [7] [8] [9] It remained on the market in the United States as late as 2004. [10]
Chlorphentermine was used as an appetite suppressant for purposes of weight loss in people with overweightness or obesity. [11] [3] [12]
Side effects of chlorphentermine include impaired sleep, irritability, and gastrointestinal symptoms including dyspepsia. [11]
Euphoria is said to occasionally occur with chlorphentermine, but to a much lesser extent than with dextroamphetamine. [3] The drug does not produce amphetamine-like subjective effects in humans [13] [14] and the psychostimulant effects of chlorphentermine are described as much less than those of dextroamphetamine. [3]
Chlorphentermine acts as a selective serotonin releasing agent (SSRA). [15] [16] [17] The EC50 for monoamine release with chlorphentermine are 30.9 nM for serotonin, >10,000 nM for norepinephrine, and 2,650 nM for dopamine. [15] [16] [17] Although it is inactive as a norepinephrine releasing agent, it is a moderately potent norepinephrine reuptake inhibitor (IC50 = 451 nM; 15-fold lower than its EC50 value for serotonin release). [18] [16] The activity of chlorphentermine as an SSRA is in contrast to phentermine, which acts as a selective norepinephrine and dopamine releasing agent (NDRA). [16] [17]
In animals, chlorphentermine robustly and dose-dependently increases serotonin levels in the brain. [19] [14] It also increases dopamine levels in the brain at high doses. [19] [14] Whereas dextroamphetamine and phentermine robustly stimulate locomotor activity and are self-administered in animals, chlorphentermine does not increase locomotor activity and is either not self-administered or is only weakly self-administered. [20] [13] [14]
In contrast to fenfluramine and norfenfluramine, chlorphentermine shows negligible activity as an agonist of the serotonin 5-HT2A, 5-HT2B, and 5-HT2C receptors. [16] Its EC50 values at these receptors are >10,000 nM, 5,370 nM, and 6,456 nM, respectively. [16] These EC50 values are >324-fold, 164-fold, and 209-fold lower than its EC50 value in inducing serotonin release, respectively. [16]
Despite its lack of direct agonism at the serotonin 5-HT2B receptors, chlorphentermine shows induction of primary pulmonary hypertension in animal models. [16] [3] This suggests that serotonin release can induce this form of toxicity without concomitant direct serotonin 5-HT2B receptor agonism. [16] However, other findings seem to contradict this hypothesis, for instance increases in serotonin levels with fenfluramine and other serotonin-elevating drugs being inadequate for inducing cardiac valvulopathy-like changes, and instead implicating additional direct serotonin 5-HT2B receptor agonism in this toxicity. [21] It has been said that it is possible that an active metabolite of chlorphentermine might show greater serotonin 5-HT2B receptor agonism than chlorphentermine itself, analogously to the case of fenfluramine and norfenfluramine, and that this possibility should be examined. [16]
The amphetamine homologue of chlorphentermine, para-chloroamphetamine (PCA), is a potent serotonergic neurotoxin. [22] In contrast to PCA, preliminary animal experiments suggest that chlorphentermine is non-neurotoxic, although more research in this area is still needed. [22]
The elimination half-life of chlorphentermine is relatively long and is stated to be 40 hours [2] and about 5 days by different sources. [3]
Chlorphentermine, also known as 4-chlorophentermine, 4-chloro-α-methylamphetamine, and 4-chloro-α,α-dimethylphenethylamine, is a substituted phenethylamine and amphetamine derivative. [19] It is the para-chloro analogue of phentermine. [19] Chlorphentermine is also closely structurally related to certain other phentermines including cericlamine, cloforex, clortermine, etolorex, and methylenedioxyphentermine (MDPH). It is closely structurally related to the amphetamine derivatives para-chloroamphetamine (PCA) and para-chloromethamphetamine (PCMA) as well. [23]
Chlorphentermine was first described in the scientific literature by 1954. [6] [7] [8] [9] It was subsequently developed for use as an appetite suppressant in the early 1960s. [6] [7] [8] [9] The drug is said to have been withdrawn from the market in the United States in 1969 [24] and in the United Kingdom in 1974. [3] However, other sources indicate that chlorphentermine continued to be marketed in the United States as late as 2004. [10] [25] Pulmonary toxicity of chlorphentermine was observed in animals by the early 1970s and this resulted in reservations about its clinical use. [3]
The drug combination fenfluramine/phentermine, usually called fen-phen, is an anti-obesity medication that is no longer widely available. It was sold in the early 1990s, and utilized two anorectics. Fenfluramine was marketed by American Home Products as Pondimin, but was shown to cause potentially fatal pulmonary hypertension and heart valve problems, which eventually led to its withdrawal in 1997 and legal damages of over $13 billion. Phentermine was not shown to have harmful effects.
A norepinephrine reuptake inhibitor or noradrenaline reuptake inhibitor or adrenergic reuptake inhibitor (ARI), is a type of drug that acts as a reuptake inhibitor for the neurotransmitters norepinephrine (noradrenaline) and epinephrine (adrenaline) by blocking the action of the norepinephrine transporter (NET). This in turn leads to increased extracellular concentrations of norepinephrine and epinephrine and therefore can increase adrenergic neurotransmission.
α-Ethyltryptamine, also known as etryptamine, is an entactogen and stimulant drug of the tryptamine family. It was originally developed and marketed as an antidepressant under the brand name Monase by Upjohn in the 1960s before being withdrawn due to toxicity.
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 Ionamin among others, is a medication used together with diet and exercise to treat obesity. It is taken by mouth for up to a few weeks at a time, after which the benefits subside. It is also available as the combination phentermine/topiramate.
Clortermine (Voranil) was developed by Ciba in the 1960s and is an anorectic drug of the amphetamine class. It is the 2-chloro analogue of the better known appetite suppressant phentermine, and is the 2-chloro positional isomer of chlorphentermine. Clortermine produces very low rates of self-administration in animals similarly to chlorphentermine, and as a result it likely does not act on dopamine. Instead, it may act as a serotonin and/or norepinephrine releasing agent.
Etilamfetamine is a stimulant drug of the phenethylamine and amphetamine chemical classes. 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. It most likely acts primarily as a dopamine releasing agent. Its activity as a norepinephrine or serotonin releasing agent is not known.
Naphthylaminopropane (PAL-287) is an experimental drug under investigation as of 2007 for the treatment of alcohol and stimulant addiction.
5-Fluoro-α-methyltryptamine, also known as PAL-544, is a putative stimulant, entactogen, and psychedelic tryptamine derivative related to α-methyltryptamine (αMT). It has been found to act as a well-balanced serotonin-norepinephrine-dopamine releasing agent, a 5-HT2A receptor agonist, and a potent and specific MAO-A inhibitor. which suggests that 5-fluoro-αMT could be an active psychedelic in humans, although it is not known to have been tested in humans and could be dangerous due to its strong inhibition of MAO-A.
para-Chloroamphetamine (PCA), also known as 4-chloroamphetamine (4-CA), is a substituted amphetamine and monoamine releaser similar to MDMA, but with substantially higher activity as a monoaminergic neurotoxin, thought to be due to the unrestrained release of both serotonin and dopamine by a metabolite. It is used as a neurotoxin by neurobiologists to selectively kill serotonergic neurons for research purposes, in the same way that 6-hydroxydopamine is used to kill dopaminergic neurons.
MDAI, also known as 5,6-methylenedioxy-2-aminoindane, is an entactogen drug of the 2-aminoindane group which is related to MDMA and produces similar subjective effects.
A monoamine releasing agent (MRA), or simply monoamine releaser, is a drug that induces the release of a monoamine neurotransmitter from the presynaptic neuron into the synapse, leading to an increase in the extracellular concentrations of the neurotransmitter. Many drugs induce their effects in the body and/or brain via the release of monoamine neurotransmitters, e.g., trace amines, many substituted amphetamines, and related compounds.
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.
4-Methylamphetamine is a stimulant and anorectic drug of the phenethylamine and amphetamine chemical classes.
3-Methylamphetamine is a stimulant drug from the amphetamine family. It is self-administered by mice to a similar extent to 4-fluoroamphetamine and has comparable properties as a monoamine releaser, although with a more balanced release of all three monoamines, as opposed to the more dopamine/noradrenaline selective fluoro analogues.
A monoamine reuptake inhibitor (MRI) is a drug that acts as a reuptake inhibitor of one or more of the three major monoamine neurotransmitters serotonin, norepinephrine, and dopamine by blocking the action of one or more of the respective monoamine transporters (MATs), which include the serotonin transporter (SERT), norepinephrine transporter (NET), and dopamine transporter (DAT). This in turn results in an increase in the synaptic concentrations of one or more of these neurotransmitters and therefore an increase in monoaminergic neurotransmission.
Levofenfluramine (INN), or (−)-3-trifluoromethyl-N-ethylamphetamine, also known as (−)-fenfluramine or (R)-fenfluramine, is a drug of the amphetamine family that, itself (i.e., in enantiopure form), was never marketed. It is the levorotatory enantiomer of fenfluramine, the racemic form of the compound, whereas the dextrorotatory enantiomer is dexfenfluramine. Both fenfluramine and dexfenfluramine are anorectic agents that have been used clinically in the treatment of obesity (and hence, levofenfluramine has been as well since it is a component of fenfluramine). However, they have since been discontinued due to reports of causing cardiovascular conditions such as valvular heart disease and pulmonary hypertension, adverse effects that are likely to be caused by excessive stimulation of 5-HT2B receptors expressed on heart valves.
A release modulator, or neurotransmitter release modulator, is a type of drug that modulates the release of one or more neurotransmitters. Examples of release modulators include monoamine releasing agents such as the substituted amphetamines and release inhibitors such as botulinum toxin A.
(R)-3,4-Methylenedioxy-N-methylamphetamine ((R)-MDMA), also known as (R)-midomafetamine or as levo-MDMA, is the (R)- or levorotatory (l-) enantiomer of 3,4-methylenedioxy-N-methylamphetamine (MDMA; midomafetamine; "ecstasy"), a racemic mixture of (R)-MDMA and (S)-MDMA. Like MDMA, (R)-MDMA is an entactogen or empathogen. It is taken by mouth.
A methylated analogue of p-chloroamphetamine is chlorphentermine (fig. 1). This compound is marketed as an appetite suppressant Pre-Sate® and it seemed of interest to reevaluate the effects of this compound on the serotonergic system. One day following the administration of 20 mg/kg to rats there appeared to be little loss of tryptophan hydroxylase in any of the brain regions; e.g., mesencephalic tegmentum 124 %, mesencephalic tectum 95.7 % and striatum 103.5 %, of control values. While this preliminary experiment would suggest that chlorphentermine is not neurotoxic, it would seem in view of the similarity of its structure to p-chloroamphetamine that considerably more detailed experiments should be done to evaluate the long-term effects of this drug and its potential neurotoxicity.