NCT04849013

Role of the Serotonin 5-HT2A Receptor in Mescaline-induced Altered States of Consciousness

• Status: Completed
• Phase: Phase 1
• Study type: Interventional
• Enrollment: 16 (actual)
• Sponsor: University Hospital, Basel, Switzerland · Academic / Other
• Sex: All
• Age: 25 Years – 65 Years
• Healthy volunteers: Accepted

Summary

Mescaline (the active substance in Peyote and San Pedro cacti) is a classic and long known serotonergic psychedelic substance (hallucinogen) that is widely used for recreational, spiritual, and/or ethno medical purposes. Despite its long history, modern data on the acute effects of mescaline on human is lacking. Mescaline produces prototypical psychedelic effects, similar as lysergic acid diethylamide (LSD) and psilocybin. The serotonin 2A (5-HT2A) receptor is thought to primarily mediate acute alterations of consciousness induced by LSD and psilocybin. However, the contributory role of the 5-HT2A receptor in mescaline-induced alterations of consciousness is unclear. Using 5-HT2A receptor antagonist ketanserin, the psychedelic experience induced by LSD and psilocybin can be attenuated and shortened. The present study therefore explores the role the 5-HT2A receptor in mescaline-induced altered states of consciousness using escalating doses of mescaline and the 5-HT2A receptor blocker ketanserin administered before a high dose of mescaline. Objective: The present MDR-study will characterize the subjective effects of different doses of mescaline using modern psychometric instruments and examine the contribution of the 5-HT2A receptor in the mescaline-induced alterations of consciousness. Design: Double-blind, placebo-controlled, 6-period cross-over design with six treatment conditions. 1) Placebo (Pla + Pla), 2) 100 mg mescaline (Pla + 100mg mescaline), 3) 200 mg mescaline (Pla + 200mg mescaline), 4) 400 mg mescaline (Pla + 400mg mescaline), 5) 800 mg mescaline (Pla + 800mg mescaline), and 6) 40mg ketanserin and 800mg mescaline (Ket + 800mg mescaline). Participants: 16 healthy participants aged ≥ 25 and ≤ 65 years (8 female, 8 male)

Conditions

• Healthy

Interventions

Type	Name	Description
DRUG	Placebo	Drug: Placebo Capsules containing mannitol looking identical to the other drugs Other: Placebo Capsules containing mannitol looking identical to the other drugs
DRUG	Mescaline 100mg	Drug: 100mg Mescaline per os, single dose Other: Placebo (Capsules containing mannitol looking identical to the other drugs)
DRUG	Mescaline 200mg	Drug: 200mg Mescaline per os, single dose Other: Placebo (Capsules containing mannitol looking identical to the other drugs)
DRUG	Mescaline 400mg	Drug: 400mg Mescaline per os, single dose Other: Placebo (Capsules containing mannitol looking identical to the other drugs)
DRUG	Mescaline 800mg	Drug: 800mg Mescaline per os, single dose Other: Placebo (Capsules containing mannitol looking identical to the other drugs)
DRUG	Mescaline 800mg + Ketanserin 40mg	Drug: 800mg Mescaline per os, single dose Other: 40mg Ketanserin per os, single dose

Timeline

• Start date: 2021-08-11
• Primary completion: 2023-03-27
• Completion: 2023-03-27
• First posted: 2021-04-19
• Last updated: 2023-03-29

Locations

1 site across 1 country: Switzerland