5-Chloro-ñMT, also known as 5-chloro-ñ-methyltryptamine or as PAL-542, is a tryptamine derivative related to ñ-methyltryptamine (ñMT) and one of only a few known serotoninâÂÂdopamine releasing agents (SDRAs). It is also a potent serotonin 5-HT<sub>2A</sub> receptor agonist and hence may be a serotonergic psychedelic. The drug has been investigated in animals as a potential treatment for cocaine dependence.
5-Chloro-ñMT is a serotoninâÂÂdopamine releasing agent (SDRA). The values of 5-chloro-ñMT in evoking the in vitro release of serotonin, dopamine, and norepinephrine in rat brain synaptosomes were reported as 16nM, 54nM, and 3,434nM, respectively. It had a norepinephrine:dopamine ratio of 64:1 and a dopamine:serotonin ratio of 3.4:1, indicating that it is a highly specific and fairly well-balanced SDRA.
However, 5-chloro-ñMT has also been found to act as a potent full agonist of the serotonin 5-HT<sub>2A</sub> receptor, with an EC<sub>50</sub> value of 6.27nM and a maximal efficacy of 105%. As a serotonin 5-HT<sub>2A</sub> receptor agonist, 5-chloro-ñMT may produce psychedelic effects. Indeed, its close analogue 5-fluoro-ñMT produces a strong head-twitch response in rats, a property which is highly correlated with psychedelic effects in humans, and ñMT is well-established as a psychedelic drug in humans.
5-Chloro-ñMT was found to not reliably produce intracranial self-administration in rats or substitute for cocaine in rats or monkeys in drug discrimination tests. It was found through study of 5-chloro-ñMT in rhesus monkeys that norepinephrine release has minimal influence on the misuse potential of monoamine releasing agents (MRAs) and that loss of norepinephrine release activity does not affect efficacy in reducing cocaine self-administration in SDRAs relative to serotoninâÂÂnorepinephrineâÂÂdopamine releasing agents (SNDRAs) such as naphthylisopropylamine (PAL-287). However, SDRAs like 5-chloro-ñMT would be expected to produce fewer side effects (including sympathomimetic/cardiovascular effects, insomnia, hyperthermia, and anxiety) relative to SNDRAs, and thus could be better-tolerated in the treatment of cocaine dependence and other conditions.
5-Chloro-ñMT is known to be a potent monoamine oxidase inhibitor (MAOI), specifically of monoamine oxidase A (MAO-A). Its values for inhibition of MAO-A and monoamine oxidase B (MAO-B) are 250nM and 82,000nM, respectively. Its potency in inhibiting MAO-A is similar to that of para-methoxyamphetamine (PMA). Other related drugs, such as 5-fluoro-ñ-methyltryptamine (5-fluoro-ñMT; PAL-544), are known to be potent MAOIs similarly to 5-chloro-ñMT. Potent monoamine oxidase inhibition by MRAs has been associated with dangerous and sometimes fatal toxicity in humans.
ñ-Ethyltryptamine (ñET), an SNDRA and close structural analogue of ñMT and 5-chloro-ñMT, like many other releasers of both serotonin and dopamine such as MDMA, has been found to produce long-lasting serotonergic neurotoxicity in rats.
Analogues of 5-chloro-AMT include ñ-methyltryptamine (AMT), 5-fluoro-AMT, 5-fluoro-AET, 5-chloro-AET, 5-chloro-DMT, 5-MeO-AMT, 6-fluoro-AMT, 7-chloro-AMT, among others. It also has structural similarities to 3-chloromethamphetamine (3-CMMA) and 5-Cl-bk-MPA.
5-Chloro-AMT was first described in the scientific literature by at least 1963.
5-Chloro-AMT has been encountered as a novel designer and recreational drug in Slovenia and online in the early 2020s.
5-Chloro-AMT is not an explicitly nor implicitly controlled substance in Canada as of 2025.
5-Chloro-AMT is illegal in Singapore.
5-Chloro-AMT is not an explicitly controlled substance in the United States. However, it could be considered a controlled substance under the Federal Analogue Act if intended for human consumption.