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Evaluation of Fluoxetine for Refractory Constipation With Somatic Symptom Disorder Features

Randomized, Double-Blind, Placebo-Controlled, Multicenter Trial to Evaluate the Efficacy and Safety of Fluoxetine in Patients With Refractory Constipation Exhibiting Somatic Symptom Disorder Features

NCT06506136•Zhifeng Zhao, PhD

View on ClinicalTrials.gov

Summary

The purpose of this randomized, double-blind, placebo-controlled trial is to determine whether fluoxetine is effective and safe for adults with refractory constipation that exhibits Somatic Symptom Disorder (SSD) features-namely, persistent preoccupation with bowel function, heightened perception of defecatory discomfort, and clinically significant somatic symptom burden (PHQ-15 ≥ 10) in the absence of IBS-C abdominal pain criteria. The study will address three primary questions: Efficacy-Bowel Function: • Does 12 weeks of fluoxetine increase Complete Spontaneous Bowel Movements (CSBM) and overall bowel-movement frequency compared with placebo? Efficacy-Somatic Symptom Burden: • Does fluoxetine reduce SSD severity, as measured by the Patient Health Questionnaire-15 (PHQ-15) and the Somatic Symptom Scale-8 (SSS-8)? Safety and Tolerability: • What adverse events occur during fluoxetine treatment, and how do their incidence and intensity compare with placebo?

Eligibility

Age

18 - 60 years

Sex

ALL

Healthy Volunteers

Inclusion Criteria

•Participants in this study were recruited from a real-world outpatient constipation patient registry platform, which provides a comprehensive case database to support evidence-based research. Based on the characteristics of the primary target population identified in previous studies of fluoxetine, participants with refractory constipation were selected from the registry according to the following criteria:
•All participants were required to meet the Rome IV diagnostic criteria for functional constipation.Specifically: 1) At least two of the following symptoms must be present during more than 25% of defecations: straining; lumpy or hard stools; sensation of incomplete evacuation; sensation of anorectal obstruction/blockage; manual maneuvers to facilitate defecation; fewer than three spontaneous bowel movements per week; 2) Loose stools are rarely present without the use of laxatives; 3) The criteria for IBS were not met.
•1. Diagnosis of Functional Constipation (FC): Participants must meet the diagnostic criteria for functional constipation according to Rome IV criteria.
•2. Low CSBM Frequency: During the 2-week screening period, participants must experience Complete Spontaneous Bowel Movements (CSBM) ≤ 2 times per week.
•3. Unsatisfactory Previous Treatments: Participants must have been dissatisfied with previous treatments for functional constipation, having undergone at least 3 months of treatment, including laxatives or other prokinetic agents.
•4. Diagnosis of Somatic Symptom Disorder (SSD): Participants must meet the diagnostic criteria for Somatic Symptom Disorder (SSD) according to DSM-5. All participants will undergo a semi-structured clinical interview based on DSM-5 criteria, conducted by professionals trained in SSD diagnosis.
•4.1. Criterion A: One or more physical symptoms that cause significant discomfort and/or disruption in daily life.
•4.2. Criterion B: At least one of the following: 1) Excessive and persistent thoughts about the severity of symptoms. 2) Persistent high anxiety about health or symptoms. 3) Excessive time and energy spent on health concerns or symptoms.
•4.3. Criterion C: The symptoms have persisted for at least 6 months.
•5. Age Range: Participants must be between the ages of 18 and 60 years.
+2 more criteria

Exclusion Criteria

•1. Organic Diseases: Participants with organic diseases (e.g., tuberculosis, Crohn's disease, tumors, congenital megacolon), endocrine disorders (e.g., hypothyroidism), metabolic diseases (e.g., diabetes, thyroid dysfunction), or neurological disorders (e.g., Parkinson's disease).
•2. Use of Medications Affecting Bowel Function: Participants who require long-term use of medications that may affect bowel function or induce constipation, such as Parkinson's medications, except for routine laxatives, antidiarrheal agents, and intestinal stimulants. Note: During the trial, participants are only allowed to use the specified emergency medications, and all medication use must be carefully recorded.
•3. Chronic Pain or Substance Abuse: Participants with a history of chronic pain lasting more than 6 months or with a pain score ≥4 (based on the visual analog scale), or a history of substance abuse.
•4. Mental Health Disorders: Participants diagnosed with psychiatric disorders before the study and continuously using psychiatric medications for more than 3 months, or those with a history of using psychiatric medications and/or corticosteroids for more than 3 months before the study.
•5. Self-harm or Suicide Risk: Participants with a risk of self-harm or suicide, as assessed by a psychologist, or those requiring psychophysical interventions.
•6. Allergic Reactions or Contraindications to Psychiatric Medications: Participants with a history of allergy to psychiatric medications, including fluoxetine, or those with liver or kidney dysfunction, or any contraindications for fluoxetine, such as prolonged QT interval on ECG.
•7. Pregnant or Breastfeeding Women: Pregnant or breastfeeding women.
•8. Other Malignant or Benign Tumors: Participants with other malignant or benign tumors or autoimmune diseases.
•9. Chronic Diseases Impacting Life Quality: Participants with cardiovascular diseases, clotting disorders (e.g., those on long-term warfarin or heparin therapy), liver or kidney diseases, organ failure, cognitive disorders, aphasia, or any other chronic diseases requiring long-term medication, which may significantly affect their quality of life and the evaluation of treatment outcomes.

Locations (2)

People's Hospital of Ningxia Hui Autonomous Region

Yinchuan, Ningxia, China

Xi'an International Medical Center Hospital

Xi'an, Shaanxi, China

Key Dates

Start Date

September 1, 2025

Primary Completion Date

June 1, 2026

Completion Date

May 30, 2027

Last Updated

August 6, 2025

Enrollment

194

ESTIMATED participants

Conditions

Refractory ConstipationSomatic Symptom Disorder (DSM-5)Functional Constipation (FC)

Interventions

Fluoxetine

DRUG

Placebo

DRUG

Contacts

Qingchuan Zhao, Prof.

CONTACT

13809153899 zhaoqc@fmmu.edu.cn

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Data Source & Attribution

This clinical trial information is sourced from ClinicalTrials.gov, a service of the U.S. National Institutes of Health.

ClinicalTrials.gov last update: August 6, 2025Data synced to Clareo: March 29, 2026

Modifications: This data has been reformatted for display purposes. Eligibility criteria have been parsed into inclusion/exclusion sections. Location data has been geocoded to enable distance-based search. For the authoritative and most current information, please visit ClinicalTrials.gov.

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Evaluation of Fluoxetine for Refractory Constipation With Somatic Symptom Disorder Features

Inclusion Criteria

Exclusion Criteria

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