Does Welchol (Colesevelam Hydrochloride) Improve Colonic Transit in Diarrhea-predominant Irritable Bowel Syndrome (D-IBS)?

Phase 2

Completed

Conditions: Irritable Bowel Syndrome
Diarrhea

Interventions: Drug: Placebo
Drug: Colesevelam

Registration Number: NCT00911612

Lead Sponsor: Mayo Clinic

Brief Summary: Our hypothesis is that the medication approved for treatment of high blood cholesterol levels, Colesevelam HCl (WELCHOL), decreases colonic transit and permeability in patients with diarrhea due to irritable bowel syndrome.

This effect is thought to result from the effect of the medication on bile acids, which can cause diarrhea.

Detailed Description: Background:

Irritable bowel syndrome (IBS) affects about 15% of the U.S. population, about 5% having predominant diarrhea; current treatment is suboptimal as it may not be tolerated, lead to side effects or insufficient benefit. Bile acid malabsorption (BAM) is recognized as a cause of chronic diarrhea and has been investigated as a mechanism for the phenotype of diarrhea predominant IBS (D-IBS). Increased exposure of the colon to bile acids which may result from accelerated small bowel transit or abnormal function of the apical sodium bile acid transporter (ASBT) has been postulated to cause functional diarrhea or symptoms of D-IBS by a number of mechanisms, such as increase colonic secretion, and mucosal permeability. Recent preliminary data suggest that doses of chenodeoxycholate (CDC) that are approved for the dissolution of gall stones are associated with accelerated colonic emptying and looser stool consistency.

Hypothesis:

The bile acid binding agent, Colesevelam HCl, decreases colonic transit and permeability in patients with D-IBS.

Specific Aim:

To investigate the effect of Colesevelam, which binds bile acids in the small intestine and reduces the concentration of bile acids in the colon, on colonic transit, permeability and the bowel function of patients with D-IBS.

Methods:

Twenty-four D-IBS participants will be randomized to placebo or treatment with Welchol (Colesevelam HCL) 1.875 gram b.i.d. for 12-14 days. A baseline colon transit, 24 hour urine for colon permeability, and blood for serum 7 alpha-hydroxy-4-cholesten-3-one (7 alpha-HCO) will be measured and venous blood DNA will be collected and stored. The measurement of serum 7 alpha-hydroxy-4-cholesten-3-one (7 alpha-HCO), which is a measurement of hepatic cholesterol synthesis, is closely related to the fecal loss of bile acids, and is a validated method for screening for BAM. Following treatment for 12 days, transit and permeability studies will be repeated. Bowel function symptoms will be recorded for the duration of the study.

Recruitment & Eligibility

Status: COMPLETED

Sex: All

Target Recruitment: 24

Inclusion Criteria

Patients with D-IBS
Aged 18-65 years
No abdominal surgery (except appendectomy or cholecystectomy as long as patients IBS-diarrhea symptoms preceded the cholecystectomy

Exclusion Criteria

Participants with known chronic liver disease or Aspartate aminotransferase (AST) or Alanine transaminase (ALT) > 2.0 X upper limit of normal
Hypertriglyceridemia and pancreatitis by history
Diabetes or hypoglycemia
Significant coagulation disorder
History of bowel obstruction
Serum triglycerides >500 mg/dL
History of vitamin A, D, E, or K deficiencies

Study & Design

Study Type: INTERVENTIONAL

Study Design: PARALLEL

Arm && Interventions

Group	Intervention	Description
Placebo	Placebo	Participants received an inert capsule matching the study drug twice daily, as prepared by the Mayo Clinic research pharmacy
Colesevelam	Colesevelam	Participants received colesevelam 1.875 g twice daily

Primary Outcome Measures

Name	Time	Method
Colonic Transit, Geometric Center at 24 Hours	After 12-14 days treatment	The scintigraphic method is used to measure colonic transit. An isotope is adsorbed on activated charcoal particles and delivered to the colon in a delayed release capsule. Anterior and posterior gamma images are taken hourly. The geometric center (GC) is the weighted average of counts in the different colonic regions. The scale ranges from 1 to 5; a high GC implies faster colonic transit. A GC of 1 implies all isotope is in the ascending colon, and a GC of 5 implies all isotope is in the stool.
Ascending Colon Emptying T1/2	After 12-14 days' treatment	The half time for the ascending colon emptying (T1/2) was measured by the scintigraphic method. An isotope is adsorbed on activated charcoal particles and delivered to the colon in a delayed release capsule that is swallowed by the subject. Anterior and posterior gamma images are taken hourly. From the hourly scans, a time-activity curve is plotted using linear interpolation between time points when content was measured. The time taken to empty 50% of the isotope from the ascending colon is read from this time-activity curve.

Secondary Outcome Measures

Name	Time	Method
Colonic Permeability as Measured by Cumulative Urinary Excretion of Mannitol 8-24 Hours	after 12-14 days' treatment	Colonic permeability is measured through differential excretion of urine saccharides. The subject ingests a methacrylate-coated capsule that contains saccharides (mannitol 1g and lactulose 5 g powder). The capsule provides a means to protect the sugars from absorption, until the sugars are delivered to the colon by means of a standard delayed release capsule. The value reported is the mean for each arm of the total amount of mannitol excreted over the 8-24 hour time period.
Colonic Transit, Geometric Center at 48 Hours	After 12-14 days' treatment	The scintigraphic method is used to measure colonic transit. An isotope is adsorbed on activated charcoal particles and delivered to the colon in a delayed release capsule. Anterior and posterior gamma images are taken hourly. The geometric center (GC) is the weighted average of counts in the different colonic regions. The scale ranges from 1 to 5; a high GC implies faster colonic transit. A GC of 1 implies all isotope is in the ascending colon, and a GC of 5 implies all isotope is in the stool.
Stool Consistency	After 12-14 days' treatment	The subjects rated their stool consistency using the Bristol Stool Scale. The Bristol Stool Scale is a medical aid designed to classify the form of human feces into seven categories or types. Types 1 and 2 indicate constipation with 3 and 4 being the "ideal stools" especially the latter, as they are the easiest to defecate, and 5-7 tending towards diarrhea.