Study of Dextromethorphan in OCD and Related Disorders

Phase 2

Recruiting

• Conditions: Body Dysmorphic Disorders; Somatic Symptom Disorder; Obsessive-Compulsive Disorder; Illness Anxiety Disorder
• Interventions: Drug: Fluoxetine; Drug: Dextromethorphan

• Registration Number: NCT04899687
• Lead Sponsor: Stanford University

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.

Detailed Description

Obsessive compulsive disorder (OCD) and the related disorders body dysmorphic disorder (BDD), somatic symptom disorder (SSD) and illness anxiety disorder (IAD) are psychiatric conditions characterized by recurrent, intrusive thoughts, feelings or images (obsessions or preoccupations) and repetitive or ritualized behaviors or avoidance performed to relieve obsession or preoccupation-related anxiety. They are a significant cause of mental health-related disability, and are inadequately served by available treatments.

This study tests whether an over-the-counter cough suppressant medicine, dextromethorphan, may offer symptom relief when combined with a low dose of fluoxetine, a standard prescription treatment for OCD and related disorders.

Study Timeline

• Study First Submitted: 2021-05-13
• Study First Submitted QC: 2021-05-20
• Study First Posted: 2021-05-24
• Study Start: 2022-01-20
• Status Verified: 2024-04
• Last Update Submitted: 2024-04-24
• Last Update Posted: 2024-04-26
• Primary Completion: 2025-04-01
• Study Completion: 2025-12-01

Recruitment & Eligibility

• Status: RECRUITING
• Sex: All
• Target Recruitment: 60

Inclusion Criteria

• 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

Exclusion Criteria

• 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

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: CROSSOVER

Arm && Interventions

Group	Intervention	Description
Group A: fluoxetine then fluoxetine plus dextromethorphan	Fluoxetine	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.
Group A: fluoxetine then fluoxetine plus dextromethorphan	Dextromethorphan	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.
Group B: fluoxetine plus dextromethorphan then fluoxetine	Fluoxetine	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.
Group B: fluoxetine plus dextromethorphan then fluoxetine	Dextromethorphan	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.

Primary Outcome Measures

Name	Time	Method
Improvement in OCD or related disorder symptoms as measured by the Y-BOCS	Change from baseline will be assessed at 4 weeks and at 8 weeks.	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.

Secondary Outcome Measures

Name	Time	Method
Improvement in clinical insight as measured by the BABS	Change from baseline will be assessed at 4 weeks and at 8 weeks.	Improvement in clinical insight is measured by the Brown Assessment of Beliefs Scale (BABS), a scale assessing multiple dimensions of clinical insight as relevant to OCD and related disorders. The BABS rates multiple dimensions of clinical insight related to an identified belief. BABS scores range from 0-24, with higher scores indicating greater insight impairment. Response will be defined as a 35% reduction in BABS score.

Trial Locations

Locations (1)

Stanford University; 🇺🇸 Stanford, California, United States