NCT06506136

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

• Status: Not Yet Recruiting
• Phase: Phase 1 / Phase 2
• Study type: Interventional
• Enrollment: 194 (estimated)
• Sponsor: Zhifeng Zhao, PhD · Academic / Other
• Sex: All
• Age: 18 Years – 60 Years
• Healthy volunteers: Not accepted

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)

Interventions

Type	Name	Description
DRUG	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.
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.

Timeline

• Start date: 2025-09-01
• Primary completion: 2026-06-01
• Completion: 2027-05-30
• First posted: 2024-07-17
• Last updated: 2025-08-06

Locations

2 sites across 1 country: China