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Pharmacology of Amanita muscaria
by Erowid
December 2001
The primary active chemicals known in Amanita muscaria and A. pantherina are: Muscimol, Ibotenic Acid, Muscazone, and Muscarine. Muscimol is considered the principle psychoactive, with oral dosages of pure muscimol around 10-15 milligrams.1,2 Ibotenic acid is also active orally, but at doses 5-8 times higher than those of muscimol.2,3 The other chemicals are only present in trace amounts in the mushrooms, well below their active levels in humans. The pharmacology of A. muscaria is not fully understood, but the following chemicals are considered the primary candidates:

Muscimol: Muscimol's primary action is at GABA receptor sites as a potent GABA-A agonist. Muscimol is commonly used in lab research on the GABA, which is a primary inhibitory neurotransmitter. Muscimol has been shown to be active in several parts of the brain including the cerebral cortex, hippocampus, and cerebellum.4

Ibotenic Acid: The current view is that some Ibotenic Acid does cross the blood brain barrier unchanged, but some is partially metabolised into muscimol and the rest excreted. Ibotenic acid, however, has been shown to be a potent neurotoxin when injected directly in the brains of mice and rats and is used as a potent brain-lesioning agent. It is structurally similar to glutamate and activates NMDA receptors, but this is not likely to be involved significantly with the effects of A. muscaria.4,5

Muscarine: Muscarine is known to affect acetylcholine levels and acts at muscarinic receptors, named for this chemical. While the levels of muscarine in A. muscaria are quite low (.002% - .003% by dry weight),5 some of the effects of A. muscaria are characteristic of cholinergic involvement.

Muscazone: Muscazone is also a possible breakdown product of Ibotenic Acid and Ott describes it as a possible "artifact of isolation procedures" which is "of dubious psychoactivity". It is not considered to be a substantial part of the psychoactive effects of A. muscaria.

Other Chemicals: Several other chemicals have been reported in A. muscaria, some of them erroneously.

Bufotenin (5-OH-DMT): One paper in 1953 (Wieland & Motzel) claimed to find bufotenin in A. muscaria extract but all subsequent research failed to confirm this result. Bufotenin is also not very potent when taken orally. Bufotenin is not believed to be present in the muscaria-class amanitas.

l-hyoscayamine (isomer of atropine): One paper (Lewis 1955) reported finding l-hyoscayamine in A. muscaria & A. pantherina from South Africa, but subsequent researchers failed to confirm this finding. This mistaken claim was repeated in the movie Altered States, but all current references consider this an error.

Misc: stizolobinic acid, stizolobic acid, methyltetrahydrocarboline carboxylic acid. Isolated by some researchers in some A. muscaria mushrooms, of unknown activity, but not considered to be significant in the psychoactive effects of the muscaria mushrooms.