Clinical TrialObsessive-Compulsive Disorder (OCD)PsilocybinPsilocybinCompleted

Psilocybin for Treatment of Obsessive Compulsive Disorder

Randomised, blinded Phase I study (n=15) comparing low-dose (100 µg/kg) and high-dose (300 µg/kg) psilocybin to lorazepam (1 mg) in participants with moderate–severe OCD; dosing weekly with masked exposure across phases.

Target Enrollment
15 participants
Study Type
Phase I interventional
Design
Randomized, quadruple Blind

Detailed Description

This two-phase, randomized study enrolls symptomatic OCD patients not taking psychoactive medications to evaluate safety, tolerability, and therapeutic effects of psilocybin versus lorazepam; all participants receive psilocybin at some point during participation in a blinded fashion.

Phase One is double-blind for participants and investigators; Phase Two is single-blind. Participants attend eight weekly dosing sessions (approximately 12 hours on-site per session); primary analyses compare low and high psilocybin doses and assess repeated-dose effects versus lorazepam.

Outcomes include symptom change, safety/tolerability, and mechanistic measures to explore how psilocybin alters brain activity relevant to OCD.

Study Protocol

Preparation

sessions

Dosing

8 sessions
720 min each

Integration

sessions

Study Arms & Interventions

Low-dose Psilocybin

experimental

Psilocybin 100 µg/kg once per week for 8 weeks (blinded exposure across phases).

Interventions

  • Psilocybin100 µg/kg
    via Oral• weekly• 8 doses total

High-dose Psilocybin

experimental

Psilocybin 300 µg/kg once per week for 8 weeks.

Interventions

  • Psilocybin300 µg/kg
    via Oral• weekly• 8 doses total

Lorazepam

active comparator

Lorazepam 1 mg once per week for 8 weeks used as an active comparator/masking agent.

Interventions

  • Compound1 mg
    via Oral• weekly• 8 doses total

    Lorazepam 1 mg (Ativan) used as active comparator and masking agent.

Participants

Ages
18 – 65
Sexes
Male & Female

Inclusion Criteria

  • Have moderate to severe OCD (DSM-5) after diagnostic interview using the Structured Clinical Interview for DSM-5 Research Version (SCID-R).
  • Failed at least one adequate attempted routine care treatment.
  • Considered safe for independent living.

Exclusion Criteria

  • Concurrent psychosis, active substance use disorder, or a personal history of psychosis.
  • Medical illness that may complicate cardiovascular safety or drug metabolism/excretion (e.g., uncontrolled hypertension, severe cardiac disease, kidney or liver failure).
  • Unstable COPD or severe sleep apnea.
  • Psychiatric comorbidity that may represent an acute risk to self or others.
  • Subjects may not be using antidepressant medication for OCD for at least two weeks before receiving study drug and cannot require sedative, narcotic, or neuroleptic medications on a regular basis; prior medications must have been stopped long enough to allow safe elimination/withdrawal.
  • Women who are pregnant, breastfeeding, or unwilling/unable to practice medically acceptable birth control during the study.
  • Allergy to lorazepam.

Study Details

Locations

University of Arizona — Tucson, Arizona, United States

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