Evaluation of Fluoxetine for Refractory Constipation With Somatic Symptom Disorder Features

NCT ID: NCT06506136

Last Updated: 2025-08-06

Basic Information

• Recruitment Status: NOT_YET_RECRUITING
• Clinical Phase: PHASE1/PHASE2
• Total Enrollment: 194 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2025-09-01
• Study Completion Date: 2027-05-30

Brief 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?

Conditions

Refractory Constipation; Somatic Symptom Disorder (DSM-5); Functional Constipation (FC)

Study Design

• Allocation Method: RANDOMIZED
• Intervention Model: PARALLEL
• Primary Study Purpose: TREATMENT
• Blinding Strategy: QUADRUPLE

Study Groups

Fluoxetine Treatment Group

Group Type: EXPERIMENTAL

Fluoxetine

Intervention Type: DRUG

Participants will receive fluoxetine tablets, 40 mg once daily, administered 30 minutes after breakfast for 12 weeks.

Emergency Rescue Medications: For participants in both groups who cannot have a bowel movement for three consecutive days or have intolerable symptoms, the following rescue medications will be provided:

polyethylene glycol：13.7 g enema Use of rescue medications must be recorded in the bowel movement diary and CRF, including date, time, and dosage. Rescue medications will be provided throughout the study but are not allowed within 48 hours before and after the first treatment. Distributed every two weeks, any bowel movements within 24 hours after rescue medication use will not count as CSBM.

Placebo Control Group

Group Type: PLACEBO_COMPARATOR

Placebo

Intervention Type: DRUG

Participants in the Placebo Control Group will receive placebo tablets that are identical in appearance and taste to the fluoxetine tablets. They will take one placebo tablet orally twice a day for 12 weeks, following the same schedule as the treatment group to maintain blinding.

Emergency Rescue Medications: For participants in both groups who cannot have a bowel movement for three consecutive days or have intolerable symptoms, the following rescue medications will be provided:

polyethylene glycol：13.7 g enema Use of rescue medications must be recorded in the bowel movement diary and CRF, including date, time, and dosage. Rescue medications will be provided throughout the study but are not allowed within 48 hours before and after the first treatment. Distributed every two weeks, any bowel movements within 24 hours after rescue medication use will not count as CSBM.

Interventions

Fluoxetine

Participants will receive fluoxetine tablets, 40 mg once daily, administered 30 minutes after breakfast for 12 weeks.

Emergency Rescue Medications: For participants in both groups who cannot have a bowel movement for three consecutive days or have intolerable symptoms, the following rescue medications will be provided:

polyethylene glycol：13.7 g enema Use of rescue medications must be recorded in the bowel movement diary and CRF, including date, time, and dosage. Rescue medications will be provided throughout the study but are not allowed within 48 hours before and after the first treatment. Distributed every two weeks, any bowel movements within 24 hours after rescue medication use will not count as CSBM.

Intervention Type: DRUG

Placebo

Participants in the Placebo Control Group will receive placebo tablets that are identical in appearance and taste to the fluoxetine tablets. They will take one placebo tablet orally twice a day for 12 weeks, following the same schedule as the treatment group to maintain blinding.

Emergency Rescue Medications: For participants in both groups who cannot have a bowel movement for three consecutive days or have intolerable symptoms, the following rescue medications will be provided:

polyethylene glycol：13.7 g enema Use of rescue medications must be recorded in the bowel movement diary and CRF, including date, time, and dosage. Rescue medications will be provided throughout the study but are not allowed within 48 hours before and after the first treatment. Distributed every two weeks, any bowel movements within 24 hours after rescue medication use will not count as CSBM.

Intervention Type: DRUG

Eligibility Criteria

Inclusion Criteria

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.

6. Not Participating in Other Ongoing Trials: Participants must not be involved in any other clinical trials during the study period.

7. Informed Consent: Participants must voluntarily agree to participate in the study and sign an informed consent form.

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.

• Minimum Eligible Age: 18 Years
• Maximum Eligible Age: 60 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: No

Sponsors

Zhifeng Zhao, PhD

OTHER

Sponsor Role: lead

Responsible Party

Zhifeng Zhao, PhD

Dr.

Responsibility Role: SPONSOR_INVESTIGATOR

Principal Investigators

Qingchuan Zhao, Prof.

Role: STUDY_CHAIR

Xijing Hospital of Digestive Diseases

Locations

People's Hospital of Ningxia Hui Autonomous Region

Yinchuan, Ningxia, China

Xi'an International Medical Center Hospital

Xi'an, Shaanxi, China

Countries

China

Central Contacts

Qingchuan Zhao, Prof.

Role: CONTACT

zhaoqc@fmmu.edu.cn

13809153899

Facility Contacts

Xuzhao Li, Prof.

Role: primary

lixuzhao@nxmu.edu.cn

18795381479

Qinxian Huang

Role: primary

qinxianhuang2022@163.com

18402938222

Other Identifiers

KY20242190

Identifier Type: -

Identifier Source: org_study_id