| Clinical data | |
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| Other names | 3,4,5-Trimethoxyphenethylamine, TMPEA, Peyote |
| AHFS/Drugs.com | mescaline |
| Routes of administration | Oral, intravenous |
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| Pharmacokinetic data | |
| Elimination half-life | 6 hours |
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| CompTox Dashboard (EPA) | |
| ECHA InfoCard | 100.000.174 |
| Chemical and physical data | |
| Formula | C11H17NO3 |
| Molar mass | 211.261 g·mol−1 |
| 3D model (JSmol) | |
| Melting point | 35 to 36 °C (95 to 97 °F) |
| Boiling point | 180 °C (356 °F) at 12 mmHg |
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Mescaline or mescalin (3,4,5-trimethoxyphenethylamine) is a naturally occurring psychedelic protoalkaloid of the substituted phenethylamine class, known for its hallucinogenic effects comparable to those of LSD and psilocybin.
It occurs naturally in several species of cacti. It is also found in small amounts in certain members of the bean family, Fabaceae, including Acacia berlandieri.[1] However those claims concerning Acacia species have been challenged and have been unsupported in any additional analysis.[2]
| Plant source | Amount of Mescaline (% of dry weight) |
|---|---|
| San Pedro cactus (Echinopsis (syn. Trichocereus) pachanoi),[3] | 0.23-4.7[4] |
| peyote cactus (Lophophora williamsii),[5] | 0.01-5.5[6] |
| Peruvian torch (Echinopsis peruviana (syn. Trichocereus peruvianus)),[7] | 0.24-0.81[4] |
| Bolivian torch cactus (Echinopsis lageniformis (syn. Trichocereus bridgesii)),[8] | 0.25-0.56[4] |
| Echinopsis macrogona (syn. Trichocereus macrogonus) | 0.01-0.05[9] |
| Echinopsis scopulicola | 0.85[4] |
| Echinopsis santaensis | 0.32[4] |
| Echinopsis uyupampensis | 0.05[4] |
| Echinopsis terscheckii (syn. Trichocereus terscheckii)[10] | 0.005 - 2.375[9][11] |
Peyote has been used for at least 5,700 years by Indigenous peoples of the Americas in Mexico.[12] Europeans noted use of peyote in Native American religious ceremonies upon early contact,[13] notably by the Huichols in Mexico. Other mescaline-containing cacti such as the San Pedro have a long history of use in South America, from Peru to Ecuador.[14][15][16] While religious and ceremonial peyote use was widespread in the Aztec empire and northern Mexico at the time of the Spanish conquest, religious persecution confined it to areas near the Pacific coast and up to southwest Texas. However, by 1880, peyote use began to spread north of South-Central America with "a new kind of peyote ceremony" inaugurated by the Kiowa and Comanche people. These religious practices, incorporated legally in the United States in 1920 as the Native American Church, has since spread as far as Saskatchewan, Canada.[12]
In traditional peyote preparations, the top of the cactus is cut off, leaving the large tap root along with a ring of green photosynthesizing area to grow new heads. These heads are then dried to make disc-shaped buttons. Buttons are chewed to produce the effects or soaked in water to drink. However, the taste of the cactus is bitter, so contemporary users will often grind it into a powder and pour it into capsules to avoid having to taste it. The usual human dosage is 200–400 milligrams of mescaline sulfate or 178–356 milligrams of mescaline hydrochloride.[17][18] The average 76 mm (3.0 in) peyote button contains about 25 mg mescaline.[19]
Mescaline was first isolated and identified in 1897 by the German chemist Arthur Heffter[20] and first synthesized in 1919 by Ernst Späth.[21]
In 1955, English politician Christopher Mayhew took part in an experiment for BBC's Panorama, in which he ingested 400 mg of mescaline under the supervision of psychiatrist Humphry Osmond. Though the recording was deemed too controversial and ultimately omitted from the show, Mayhew praised the experience, calling it "the most interesting thing I ever did".[22]
Mescaline has a wide array of suggested medical usage, including treatment of alcoholism[23] and depression.[24] However, its status as a Schedule I controlled substance in the Convention on Psychotropic Substances limits availability of the drug to researchers. Because of this, very few studies concerning mescaline's activity and potential therapeutic effects in humans have been conducted since the early 1970s.[25][26][27]
Mescaline is biosynthesized from tyrosine which, in turn, is derived from phenylalanine by the enzyme phenylalanine hydroxylase. In Lophophora williamsii (Peyote), dopamine converts into mescaline in a biosynthetic pathway involving m-O-methylation and aromatic hydroxylation.[28]
Tyrosine and phenylalanine serve as the metabolic precursors to synthesis of mescaline. Tyrosine can either undergo a decarboxylation via tyrosine decarboxylase to generate tyramine and subsequently undergo an oxidation at carbon 3 by a monophenol hydroxylase or first be hydroxylated by tyrosine hydroxylase to form L-DOPA and decarboxylated by DOPA decarboxylase. These create dopamine, which then experiences methylation by a catechol-O-methyltransferase (COMT) by an S-adenosyl methionine (SAM)-dependent mechanism. The resulting intermediate is then oxidized again by a hydroxylase enzyme, likely monophenol hydroxylase again, at carbon 5, and methylated by COMT. The product, methylated at the two meta positions with respect to the alkyl substituent, experiences a final methylation at the 4 carbon by a guaiacol-O-methyltransferase, which also operates by a SAM-dependent mechanism. This final methylation step results in the production of mescaline.
Phenylalanine serves as a precursor by first being converted to L-tyrosine by L-amino acid hydroxylase. Once converted, it follows the same pathway as described above.[29][30]
Mescaline was first synthesized in 1919 by Ernst Späth from 3,4,5-trimethoxybenzoyl chloride.[21] Subsequent to this, numerous approaches utilizing different starting materials have been developed. Notable examples include the following:
Tolerance builds with repeated usage, lasting for a few days. Mescaline causes cross-tolerance with other serotonergic psychedelics such as LSD and psilocybin.[48]
About half the initial dosage is excreted after 6 hours, but some studies suggest that it is not metabolized at all before excretion. Mescaline appears not to be subject to metabolism by CYP2D6[49] and between 20% and 50% of mescaline is excreted in the urine unchanged, with the rest being excreted as the deaminated-oxidised-carboxylic acid form of mescaline, a likely result of MAO degradation.[50] The LD50 of mescaline has been measured in various animals: 212 mg/kg i.p. (mice), 132 mg/kg i.p. (rats), and 328 mg/kg i.p. (guinea pigs). For humans, the LD50 of mescaline has been reported to be approximately 880 mg/kg.[51]
Mescaline induces a psychedelic state comparable to those produced by LSD and psilocybin, but with unique characteristics.[27] Subjective effects may include altered thinking processes, an altered sense of time and self-awareness, and closed- and open-eye visual phenomena.[47]
Prominence of color is distinctive, appearing brilliant and intense. Recurring visual patterns observed during the mescaline experience include stripes, checkerboards, angular spikes, multicolor dots, and very simple fractals that turn very complex. The English writer Aldous Huxley described these self-transforming amorphous shapes as like animated stained glass illuminated from light coming through the eyelids in his autobiographical book The Doors of Perception (1954). Like LSD, mescaline induces distortions of form and kaleidoscopic experiences but they manifest more clearly with eyes closed and under low lighting conditions.[52]
Heinrich Klüver coined the term "cobweb figure" in the 1920s to describe one of the four form constant geometric visual hallucinations experienced in the early stage of a mescaline trip: "Colored threads running together in a revolving center, the whole similar to a cobweb". The other three are the chessboard design, tunnel, and spiral. Klüver wrote that "many 'atypical' visions are upon close inspection nothing but variations of these form-constants."[53]
As with LSD, synesthesia can occur especially with the help of music.[54] An unusual but unique characteristic of mescaline use is the "geometrization" of three-dimensional objects. The object can appear flattened and distorted, similar to the presentation of a Cubist painting.[55]
Mescaline elicits a pattern of sympathetic arousal, with the peripheral nervous system being a major target for this substance.[54]
Mescaline is produced when products of natural mammalian catecholamine-based neuronal signaling such as dopamine and noradrenaline are subjected to additional metabolism via methylation, and mescaline's hallucinogenic properties stem from its structural similarities with these two neurotransmitters. In plants, this compound may be the end-product of a pathway utilizing catecholamines as a method of stress response, similar to how animals may release such compounds and others such as cortisol when stressed. The in vivo function of catecholamines in plants has not been investigated, but they may function as antioxidants, as developmental signals, and as integral cell wall components that resist degradation from pathogens. The deactivation of catecholamines via methylation produces alkaloids such as mescaline.[29]
In humans, Mescaline acts similarly to other psychedelic agents.[56] It acts as an agonist,[57] binding to and activating the serotonin 5-HT2A receptor with a high affinity.[58] How activating the 5-HT2A receptor leads to psychedelia is still unknown, but it is likely that somehow it involves excitation of neurons in the prefrontal cortex.[59] Mescaline is also known to have even greater binding affinity for the serotonin 5-HT2C receptor.[60]
| Binding sites | Binding affinity Ki (μM)[61] |
|---|---|
| 5-HT1A | 4.6 |
| 5-HT2A | 6.3 |
| 5-HT2C | 17 |
| α1A | >15 |
| α2A | 1.4 |
| TAAR1 | 3.3 |
Difluoromescaline and trifluoromescaline are more potent than mescaline, as is its amphetamine homologue trimethoxyamphetamine.[62][63] Escaline and proscaline are also both more potent than mescaline, showing the importance of the 4-position substituent with regard to receptor binding.[64]
In the United States, mescaline was made illegal in 1970 by the Comprehensive Drug Abuse Prevention and Control Act, categorized as a Schedule I hallucinogen.[65] The drug is prohibited internationally by the 1971 Convention on Psychotropic Substances.[66] Mescaline is legal only for certain religious groups (such as the Native American Church by the American Indian Religious Freedom Act of 1978) and in scientific and medical research. In 1990, the Supreme Court ruled that the state of Oregon could ban the use of mescaline in Native American religious ceremonies. The Religious Freedom Restoration Act (RFRA) in 1993 allowed the use of peyote in religious ceremony, but in 1997, the Supreme Court ruled that the RFRA is unconstitutional when applied against states.[citation needed] Many states, including the state of Utah, have legalized peyote usage with "sincere religious intent", or within a religious organization,[citation needed] regardless of race.[67]
While mescaline-containing cacti of the genus Echinopsis are technically controlled substances under the Controlled Substances Act, they are commonly sold publicly as ornamental plants.[68]
In the United Kingdom, mescaline in purified powder form is a Class A drug. However, dried cactus can be bought and sold legally.[69]
Mescaline is considered a schedule 9 substance in Australia under the Poisons Standard (February 2020).[70] A schedule 9 substance is classified as "Substances with a high potential for causing harm at low exposure and which require special precautions during manufacture, handling or use. These poisons should be available only to specialised or authorised users who have the skills necessary to handle them safely. Special regulations restricting their availability, possession, storage or use may apply."[70]
The peyote cacti and other mescaline-containing plants such as San Pedro are illegal in Western Australia, Queensland, and the Northern Territory, whilst in other states such as Tasmania, Victoria and New South Wales, they are legal for ornamental and gardening purposes
In Canada, France, The Netherlands and Germany, mescaline in raw form and dried mescaline-containing cacti are considered an illegal drug. However, anyone may grow and use peyote, or Lophophora williamsii, as well as Echinopsis pachanoi and Echinopsis peruviana without restriction, as it is specifically exempt from legislation.[5] In Canada, mescaline is classified as a schedule III drug under the Controlled Drugs and Substances Act, whereas peyote is exempt.[71]
In Russia mescaline, its derivatives and mescaline-containing plants are banned as narcotic drugs (Schedule I).[72]
![Laboratory synthetic mescaline. Biosynthesized by peyote, this was the first psychedelic compound to be extracted and isolated.[31]](http://upload.wikimedia.org/wikipedia/commons/thumb/c/cf/Synthetic_mescaline_powder_i2001e0151_ccby3.jpg/440px-Synthetic_mescaline_powder_i2001e0151_ccby3.jpg)
