THPC (drug)
Pharmaceutical compound
From Wikipedia, the free encyclopedia
THPC, also known as 1-methyl-1,2,5,6-tetrahydropyridine-3-diethylcarboxamide, is a greatly simplified analogue of the psychedelic lysergamide lysergic acid diethylamide (LSD) in which only a modified version of the D ring (and its substitutions) remains.[1][2][3][4][5]
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| Other names | 1-Methyl-1,2,5,6-tetrahydropyridine-3-(N,N-diethylcarboxamide); 1-Methyl-1,2,5,6-tetrahydropyridine-3-diethylcarboxamide |
| Drug class | Serotonin antagonist; Serotonin 5-HT2A receptor antagonist; Hallucinogen antidote |
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| Formula | C11H20N2O |
| Molar mass | 196.294 g·mol−1 |
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THPC was assessed and produced no behavioral effects by itself in rodents.[1][2][4] However, the drug was reported to markedly potentiate the behavioral effects of mescaline and to inhibit the effects of LSD in rodents.[1][2][3][4] It was suggested that THPC might be clinically useful as a hallucinogen antagonist against LSD, for instance in the context of recreational LSD use.[5] In any case, findings of these studies were based on very small numbers of animals and have been limitedly or not replicated.[1][6]
Subsequent studies of THPC in several in vitro and in vivo systems have provided mixed results.[7] It has been found to strongly contract smooth muscle, but the mechanism of this action, such as α-adrenergic or histamine receptor activation, has not been determined, except that it was not reversed by serotonin antagonists.[2] In another study, THPC antagonized the contractions of sheep umbilical vasculature induced by serotonin, mescaline, and LSD, and it was concluded that THPC is a weak serotonin antagonist.[1][7][8] Accordingly, THPC was found to completely block LSD binding to receptors in synaptosomal membranes from rat forebrain.[7][9][10] However, THPC reportedly did not block serotonin binding in this preparation.[10] In any case, this binding site is said to have been later identified as the serotonin 5-HT2A receptor in 1979.[1] In other studies, THPC did not block various specific effects of mescaline and LSD.[1][7][6]
THPC was first described in the scientific literature by John Raymond Smythies and colleagues in 1970.[1][2][3][4][5] It was reviewed by David E. Nichols in his thesis in 1973[2] and by Steven A. Barker in 2025.[1] Along with other drugs like chlorpromazine, 2-bromo-LSD, and cinanserin, THPC was one of the first claimed antagonists of the behavioral effects of LSD to be identified.[1][9][11] Various analogues of THPC have also been synthesized and studied, including as serotonin antagonists.[1][5][6]