Study of Dextromethorphan in OCD and Related Disorders

NCT04899687 | Recruiting Phase 2 FDA Drug

• 1 other identifier: 60569
• Study Type: interventional
• Target: 60
• Locations: 1 country
• Sites: 1

Brief Summary

The purpose of the study is to assess the tolerability and efficacy of dextromethorphan in combination with fluoxetine for symptom relief in OCD and related disorders.

Conditions

Obsessive-Compulsive Disorder; Illness Anxiety Disorder; Body Dysmorphic Disorders; Somatic Symptom Disorder

Keywords

OCD; BDD; IAD; SSD; Fluoxetine; Dextromethorphan

Outcome Measures

Primary Outcomes (1)

• Improvement in OCD or related disorder symptoms as measured by the Y-BOCS

  Improvement in OCD severity is measured by the Yale-Brown Obsessive Compulsive Scale (Y-BOCS), a gold standard measure of the severity of obsessions and compulsions. Variants of the Y-BOCS designed for assessment of body dysmorphic disorder or illness anxiety disorder/somatic symptom disorder will be used as appropriate. Y-BOCS scores range from 0 to 40, with higher scores indicating greater severity of symptoms. Response will be defined as a 35% reduction in Y-BOCS score.

  Change from baseline will be assessed at 4 weeks and at 8 weeks.

Secondary Outcomes (1)

• Improvement in clinical insight as measured by the BABS

  Change from baseline will be assessed at 4 weeks and at 8 weeks.

Study Arms (2)

Group A: fluoxetine then fluoxetine plus dextromethorphan

EXPERIMENTAL

Group A participants will take fluoxetine 20mg (or prior dose) daily for 4 weeks, and will then continue fluoxetine while adding over the counter dextromethorphan, with doses increasing weekly as tolerated, for 4 weeks.

Drug: Fluoxetine; Drug: Dextromethorphan

Group B: fluoxetine plus dextromethorphan then fluoxetine

EXPERIMENTAL

Group B participants will take fluoxetine 20mg (or prior dose) daily together with over the counter dextromethorphan, with doses increasing weekly as tolerated, for 4 weeks, and then will stop dextromethorphan, continuing fluoxetine alone for 4 weeks.

Drug: Fluoxetine; Drug: Dextromethorphan

Interventions

Fluoxetine DRUG

Fluoxetine 20mg (or previously prescribed dose) will be taken once daily by mouth for 8 weeks

Also known as: Prozac

Group A: fluoxetine then fluoxetine plus dextromethorphan; Group B: fluoxetine plus dextromethorphan then fluoxetine

Dextromethorphan DRUG

Dextromethorphan, an over-the-counter cough suppressant, will be taken by mouth twice daily for four weeks of the study, starting at 15mg per dose, and increasing weekly as tolerated to a maximum of 60mg per dose.

Group A: fluoxetine then fluoxetine plus dextromethorphan; Group B: fluoxetine plus dextromethorphan then fluoxetine

Eligibility Criteria

• Age: 18 Years - 65 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Diagnosis of obsessive-compulsive disorder (OCD), body dysmorphic disorder (BDD), illness anxiety disorder (IAD) or somatic symptom disorder (SSD)
• Living within California
• Capacity to provide informed consent

You may not qualify if:

• Current bipolar disorder or psychotic disorder
• Active moderate or severe substance use disorder, lifetime severe substance use disorder
• Pregnant or nursing women
• Use of prescribed psychotropic medications other than fluoxetine for 2 weeks prior to study start
• Having commenced OCD-targeted exposure and response-prevention (ExRP) psychotherapy within 2 months of study start

Sponsors & Collaborators

• Stanford University: lead
• Avy L. & Roberta L. Miller Foundation: collaborator

Study Sites (1)

Stanford University

Stanford, California, 94304, United States

RECRUITING

MeSH Terms

Conditions

Obsessive-Compulsive Disorder; Body Dysmorphic Disorders

Interventions

Fluoxetine; Dextromethorphan

Condition Hierarchy (Ancestors)

Anxiety Disorders; Mental Disorders; Somatoform Disorders

Intervention Hierarchy (Ancestors)

Propylamines; Amines; Organic Chemicals; Morphinans; Opiate Alkaloids; Alkaloids; Heterocyclic Compounds; Heterocyclic Compounds, Bridged-Ring; Heterocyclic Compounds, 4 or More Rings; Heterocyclic Compounds, Fused-Ring; Phenanthrenes; Polycyclic Aromatic Hydrocarbons; Polycyclic Compounds

Study Officials

• Peter J van Roessel, MD PhD

  Stanford University

  PRINCIPAL INVESTIGATOR

Central Study Contacts

Pavithra Mukunda, MS

CONTACT

650 497 2578; ocdresearch@stanford.edu

Study Design

• Study Type: interventional
• Phase: phase 2
• Allocation: RANDOMIZED
• Masking: SINGLE
• Who Masked: OUTCOMES ASSESSOR
• Masking Details: Symptom rating will be done by independent evaluators blind to treatment allocation.
• Purpose: TREATMENT
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Clinical Associate Professor

Model Details: After signing consent and baseline assessments, participants will be randomized 1:1 to Group A or Group B for the purposes of sequencing fluoxetine vs combined fluoxetine/dextromethorphan treatment periods.

Study Record Dates

• First Submitted: May 13, 2021
• First Posted: May 24, 2021
• Study Start: January 20, 2022
• Primary Completion: April 1, 2026
• Study Completion (Estimated): December 1, 2026
• Last Updated: August 27, 2025

Record last verified: 2025-08

Data Sharing

• IPD Sharing: Will not share

Locations

US (1)