does welchol (colesevelam hydrochloride) improve colonic transit in diarrhea-predominant irritable bowel syndrome (d-ibs)?

Conditions: Irritable Bowel Syndrome; Diarrhea

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.

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.

Eligibility criteria:
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

Keywords: bile acid malabsorption permeability diarrhea ibs stool