Pharmacokinetic and Pharmacodynamic Aspects of Peyote and Mescaline: Clinical and Forensic Repercussions

Mescaline, a hallucinogenic agent found in the Peyote cactus, has poorly understood psychoactive mechanisms despite being one of the oldest known such substances. Its effects are primarily due to interaction with serotonergic 5-HT2A-C receptors, producing euphoria, hallucinations, depersonalization, and psychoses similar to LSD and psilocybin, alongside sympathomimetic signs. The drug is mainly metabolized into trimethoxyphenylacetic acid, with several minor metabolites reported. Most intoxications are mild and unlikely to produce life-threatening symptoms; addiction and dependence are practically absent, supporting contemporary interest in therapeutic potential.

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Abstract

Background:Mescaline (3,4,5-trimethoxyphenethylamine), mainly found in the Peyote cactus (Lophophora williamsii), is one of the oldest known hallucinogenic agents that influence human and animal behavior, but its psychoactive mechanisms remain poorly understood.Objective:This article aims to fully review pharmacokinetics and pharmacodynamics of mescaline, focusing on the in vivo and in vitro metabolic profile of the drug and its implications for the variability of response.Methods:Mescaline pharmacokinetic and pharmacodynamic aspects were searched in books and in PubMed (U.S. National Library of Medicine) without a limiting period. Biological effects of other compounds found in peyote were also reviewed.Results:Although its illicit administration is less common, in comparison with cocaine and Cannabis, it has been extensively described in adolescents and young adults, and licit consumption often occurs in religious and therapeutic rituals practiced by the Native American Church. Its pharmacodynamic mechanisms of action are primarily attributed to the interaction with the serotonergic 5-HT2A-C receptors, and therefore clinical effects are similar to those elicited by other psychoactive substances, such as lysergic acid diethylamide (LSD) and psilocybin, which include euphoria, hallucinations, depersonalization and psychoses. Moreover, as a phenethylamine derivative, signs and symptoms are consistent with a sympathomimetic effect. Mescaline is mainly metabolized into trimethoxyphenylacetic acid by oxidative deamination but several minor metabolites with possible clinical and forensic repercussions have also been reported.Conclusion:Most reports concerning mescaline were presented in a complete absence of exposure confirmation, since toxicological analysis is not widely available. Addiction and dependence are practically absent and it is clear that most intoxications appear to be mild and are unlikely to produce lifethreatening symptoms, which favors the contemporary interest in the therapeutic potential of the drugs of the class.