Tetrahydroharmine

Use and effects

THH has been reported to produce psychoactive effects similar to those of harmaline in humans. It has been reported to be about one-third as potent as harmaline at a dose of 300mg orally. THH is believed to be one of the constituents of Banisteriopsis caapi responsible for the hallucinogenic effects of the plant. The duration of THH is unknown.

Pharmacology

Pharmacodynamics

THH, like other harmala alkaloids in B. caapi, namely harmaline and harmine, is a reversible inhibitor of monoamine oxidase A (RIMA), but it also inhibits the reuptake of serotonin. THH contributes to B. caapi's psychoactivity as a serotonin reuptake inhibitor. In contrast to other β-carbolines, THH shows minimal affinity for the serotonin 5-HT2A receptor (Ki = 10,000nM for racemic THH and R(+)-THH, Ki = 5,890nM for S(–)-THH). Similarly, THH shows negligible affinity for the serotonin 5-HT1A and 5-HT2C receptors and the dopamine D2 receptor.

Pharmacokinetics

The elimination half-life of tetrahydroharmine is 4.7 to 8.8hours.

Chemistry

Synthesis

The chemical synthesis of tetrahydroharmine has been described.

Society and culture

Legal status

Australia

Harmala alkaloids are considered Schedule 9 prohibited substances under the Poisons Standard (October 2015). A Schedule 9 substance is a substance which may be abused or misused, the manufacture, possession, sale or use of which should be prohibited by law except when required for medical or scientific research, or for analytical, teaching or training purposes with approval of Commonwealth and/or State or Territory Health Authorities.

Canada

THH is not a controlled substance in Canada as of 2025.

References

References

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3. {{CiteTiHKAL
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6. (July 2017). "The alkaloids of Banisteriopsis caapi, the plant source of the Amazonian hallucinogen Ayahuasca, stimulate adult neurogenesis in vitro". Springer Science and Business Media LLC.
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8. (April 1998). "Investigation of hallucinogenic and related beta-carbolines". Drug Alcohol Depend.
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10. (2022). "Monoamine Oxidase Inhibition by Plant-Derived β-Carbolines; Implications for the Psychopharmacology of Tobacco and Ayahuasca". Front Pharmacol.
11. (October 2020). "Toxicokinetics and Toxicodynamics of Ayahuasca Alkaloids N,N-Dimethyltryptamine (DMT), Harmine, Harmaline and Tetrahydroharmine: Clinical and Forensic Impact". Pharmaceuticals (Basel).
12. (September 2015). "Poisons Standard October 2015". Australian Government Department of Health.
13. "Controlled Drugs and Substances Act".