Glucuronidation is one of the body’s main ways of tagging molecules for removal: an enzyme attaches glucuronic acid, a sugar-derived group, which makes the molecule easier to excrete in urine. For psilocin, a 2017 review names psilocin-O-glucuronide as the main urinary metabolite (Dinis-Oliveira, 2017).
It affects what tests find. In a 2002 study, adding the enzyme beta-glucuronidase to urine roughly doubled the psilocin measured, which showed that much of it is excreted attached to glucuronic acid; the authors concluded that this step extends the time psilocin can be detected (Hasler et al., 200200278-9)). A 2017 study found that less than 2% of psilocin’s total clearance was renal clearance of intact psilocin (Brown et al., 2017).
The tag can also come off again. The 2017 authors suggest that psilocin released from its glucuronide may explain a longer elimination tail seen in some people (Brown et al., 2017). Glucuronidation is not unique to psychedelics; it handles many medicines and the body’s own compounds.
Sources
- Dinis-Oliveira, 2017, Drug Metabolism Reviews
- Hasler et al., 2002, Journal of Pharmaceutical and Biomedical Analysis
- Brown et al., 2017, Clinical Pharmacokinetics
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