Pharmacokinetics
Tolerance builds with repeated usage, lasting for a few days. Mescaline causes cross-tolerance with other serotonergic psychedelics such as LSD and psilocybin.
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 to not be subject to metabolism by CYP2D6 and between 20% and 50% of mescaline is excreted in the urine unchanged, and the rest being excreted as the carboxylic acid form of mescaline, a likely result of MAO degradation. 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).
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