Isoxazoles

The isoxazole alkaloids of Amanita muscaria and its relatives. Muscimol is a potent agonist at the GABA-A receptor — the same receptor the sedative-hypnotics act on, though muscimol occupies the orthosteric site rather than modulating it. Ibotenic acid, its biosynthetic precursor, is instead a glutamate agonist and an excitotoxin, and decarboxylates to muscimol on drying and heating; the ratio between the two in any given specimen or preparation is not something a reader can assume. Muscarine is filed here too, though it is not an isoxazole — it is a muscarinic agonist and a separate toxidrome, named after this mushroom rather than typical of it.

Filing "magic mushrooms" reflexively under Psychedelics would be wrong: there is no tryptamine in these, no 5-HT2A agonism and no psilocybin. What hurts people is the ibotenic acid — nausea, vomiting and a confusional delirium — and misidentification, since Amanita is a genus with lethal members.