Safety, Tolerability, and Preliminary Efficacy of Psilocybin Oral Solution in Adults With Generalized Anxiety Disorder

This Phase IIa, placebo-controlled, double-blind trial (n=50) will study the safety, tolerability, and preliminary efficacy of a 3 mg dose of psilocybin (oral solution) in adults with generalised anxiety disorder (GAD).

Conducted by Queen’s University in Canada and sponsored in collaboration with Diamond Therapeutics, this study consists of three stages: a 4-week screening period, a 4-week open-label phase (where all participants receive daily psilocybin), and a 4-week double-blind phase where only those who show a 50% or greater reduction in anxiety symptoms will be randomly assigned to continue with psilocybin or switch to a placebo.

The primary goal is to assess adverse events and tolerability, while secondary measures include reductions in anxiety symptoms, tracked via standard scales such as the Hamilton Anxiety Rating Scale (HAM-A). Participants are adults aged 18–60 diagnosed with GAD and not currently on daily anxiolytic (anti-anxiety) medication. The study will also collect cognitive data and neurophysiological measures (like EEG) across the treatment period. The trial is expected to run from May 2025 to August 2026.

Topic Anxiety Safety
Compound Placebo Psilocybin
Country Canada
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Queen's University
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