Cross tolerance between mescaline and LSD-25, with a comparison of the mescaline and LSD reactions.

Abstract

1. The reactions caused by intramuscular administration of 0.75 mcg/ kg and 1.5 meg/kg of LSD-25 have been compared in the same 10 subjects with those induced by 2.5 mg/kg and 5.0 mg/kg of mescaline. 2. Both LSD and mescaline caused dilatation of the pupils, increase in body temperature, elevation of pulse rate and increase in systolic blood pressure. Both drugs decreased the threshold for elicitation of the kneejerk. 3. After both drugs, similar abnormal mental states characterized by anxiety, difficulty in thinking, alteration in mood (generally euphoric), altered sensory perception (particularly visual), elementary and true visual hallucinations and alterations of body image were reported by the subjects. 4. The effects of mescaline appeared more slowly and persisted somewhat longer than did the effects of LSD. 5. LSD tartrate is 2400–4900 times as potent as mescaline hydrochloride. On a molecular basis, LSD is 4500 to 9275 times as potent as mescaline. 6. Patients receiving LSD daily developed direct tolerance to LSD; such patients were also cross tolerant to mescaline. Likewise patients receiving mescaline daily became tolerant to mescaline and cross tolerant to LSD. 7. It was inferred that LSD, psilocybin and mescaline probably share common mechanisms of action or some common final pathway.