CI

At a glance

ClinicalIndex Comparison Record
Phase 2Completed· 347 enrolled
Drug / intervention
Psilocybin +2 moredrug
Likely dose
Psilocybin 25 mgfrom record
Structured eligibility isn't available for this trial yet — see the full criteria in the Eligibility tab below.

Standardized by ClinicalIndex from the ClinicalTrials.gov record · verify against the source.

Search/NCT03866174
NCT03866174Phase 2Completed

A Randomized, Double-Blind Study of Single-Dose Psilocybin for Major Depressive Disorder (MDD)

Usona Institute·interventional·Posted Mar 7, 2019·Updated Apr 22, 2026

In Brief

A Phase 2 clinical trial evaluating Psilocybin, Niacin, and 1 other intervention for Depressive Disorder, Major. Completed, enrolled 347 participants across 11 sites.

Detailed Summary

One hundred participants, ages 21 to 65, who meet Diagnostic and Statistical Manual of Mental Disorders (DSM-5) criteria for major depressive disorder (MDD) will be stratified by study site and randomized with a 1-to-1 allocation under double-blind conditions to receive a single 25 mg oral dose of psilocybin or a single 100 mg oral dose of niacin. Niacin will serve as an active placebo. The purpose of this study is to evaluate the potential efficacy of a single 25 mg oral dose of psilocybin for MDD compared to the active placebo in otherwise medically-healthy participants, assessed as the difference between groups in changes in depressive symptoms from Baseline to Day 43 post-dose.

Study Details

Study Typeinterventional
Allocation--
Masking--
Primary Purpose--
CountriesUnited States

Timeline

Phase 2CompletedFinished
20192020202120222023202420252026
First PostedMar 7, 2019
Enrollment StartJan 23, 2020
Primary CompletionJun 28, 2022
TodayJul 2, 2026
Enrollment to primary: 2.4 yearsPosted 7.3 years ago

Interventions

Psilocybindrug

The psilocybin used in this study is synthetically manufactured in a laboratory and meets quality specifications suitable for human research use. The active drug is encapsulated using a hydroxypropyl methylcellulose (HPMC) capsule and contains 25 mg of psilocybin.

Niacindrug

The active placebo is encapsulated using a HPMC capsule and contains 100 mg of pharmaceutical grade niacin.

Set and Setting (SaS) Protocolother

The SaS Protocol prescribes 6-8 hours of preparatory meetings with two facilitators prior to dosing, a 7-10 hour dosing session in a comfortable room under the supervision of the same two facilitators, and 4 hours of post-dose integration sessions with facilitators. During the dosing session participants are encouraged to wear eyeshades and listen to a curated playlist on headphones.