Evaluation of Fluoxetine for Refractory Constipation With Somatic Symptom Disorder Features

Phase 1

Not yet recruiting

• Conditions: Refractory Constipation; Somatic Symptom Disorder (DSM-5); Functional Constipation (FC)
• Interventions: Drug: Fluoxetine; Drug: Placebo

• Registration Number: NCT06506136
• Lead Sponsor: Zhifeng Zhao, PhD

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?

Detailed Description

Not available

Study Timeline

• Study First Submitted: 2024-07-11
• Study First Submitted QC: 2024-07-11
• Study First Posted: 2024-07-17
• Status Verified: 2025-08
• Last Update Submitted: 2025-08-03
• Last Update Posted: 2025-08-06
• Study Start: 2025-09-01
• Primary Completion: 2026-06-01
• Study Completion: 2027-05-30

Recruitment & Eligibility

• Status: NOT_YET_RECRUITING
• Sex: All
• Target Recruitment: 194

Inclusion Criteria

Not provided

Exclusion Criteria

Not provided

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: PARALLEL

Arm && Interventions

Group	Intervention	Description
Fluoxetine Treatment Group	Fluoxetine	-
Placebo Control Group	Placebo	-

Primary Outcome Measures

Name	Time	Method
Efficacy rate of fluoxetine treatment	Baseline (Week -2) through the end of Week 12 (treatment period)	The primary efficacy endpoint is the proportion (%) of participants who achieve an increase of ≥ 1 complete spontaneous bowel movement (CSBM) per week relative to baseline in at least four of the twelve treatment weeks, a key indicator of therapeutic response in functional constipation (FC).

Secondary Outcome Measures

Name	Time	Method
Proportion of Participants Achieving ≥3 CSBM per Week	baseline and 12-week	Percentage of participants who achieve at least 3 complete spontaneous bowel movements (CSBM) per week during the 12-week treatment period.
Change in the SBM compared to baseline over the 12-week treatment period	Baseline to Week-12	Refers to a bowel movement occurring within the past 24 hours without the use of rescue medications or any other adjunctive methods (e.g., laxatives, enemas, suppositories, or digital maneuvers), including CSBM
Change from Baseline in Weekly CSBM Frequency	Baseline to Week-12	The mean change in weekly complete spontaneous bowel movements (CSBM) compared to baseline.
Change in the average straining score for SBM over 12 weeks compared to baseline	Baseline to Week-12	0 = no difficulty; 1. = mild difficulty, straining required; 2. = moderate difficulty, straining required; 3. = severe difficulty, intense straining required.
Change in the abdominal bloating score compared to baseline over the 12-week treatment period	Baseline to Week-12	Abdominal bloating will be assessed using a 5-point ordinal scale: 1. = none; 2. = mild; 3. = moderate; 4. = severe; 5. = very severe.
Change in the average stool consistency score for SBM over 12 weeks compared to baseline	Baseline to Week-12	Participants will self-report the stool consistency of each SBM using the Bristol Stool Form Scale
The change in KESS score from baseline to the end of the treatment period	Baseline to Week-12	A validated questionnaire designed to quantify the severity and symptom profile of chronic constipation. It consists of 11 items, each scored from 0 to 4 based on symptom severity. Higher total scores indicate more severe constipation symptoms.
Change in PAC-QOL self-assessment scores from baseline	Baseline to Week-12	A validated constipation-specific quality of life instrument developed to assess the impact of constipation on daily living. It includes 28 items covering four domains: physical discomfort, psychosocial discomfort, worries and concerns, and satisfaction, reflecting the effect of constipation over the past two weeks.
The change in GAD-7 score from baseline to the end of the treatment period	Baseline to Week-12	Change in the Generalized Anxiety Disorder-7 (GAD-7) score from baseline to Week 12, assessing anxiety symptoms.
The change in PHQ-9 score from baseline to the end of the treatment period	Baseline to Week-12	Change in the Patient Health Questionnaire-9 (PHQ-9) score from baseline to Week 12, assessing depressive symptoms.
The change in PHQ-15 score from baseline to the end of the treatment period	Baseline to Week-12	Change in the Patient Health Questionnaire-15 (PHQ-15) score from baseline to Week 12, assessing somatic symptom severity related to SSD.
Incidence of adverse events	Weeks-2-12	The proportion of participants experiencing adverse events in each treatment group during the study period.

Trial Locations

Locations (2)

People's Hospital of Ningxia Hui Autonomous Region; 🇨🇳 Yinchuan, Ningxia, China

Xi'an International Medical Center Hospital; 🇨🇳 Xi'an, Shaanxi, China