Defining normal pouch function in patients with ileal pouch-anal anastomosis: a pilot study.

BACKGROUND: Most patients experience good functional outcomes following ileal pouch-anal anastomosis (IPAA) for ulcerative colitis. AIM: We aimed to determine if asymptomatic patients with an IPAA had findings consistent with normal defecation on standard objective anorectal tests. METHODS: Patients 18-65 years old with IPAA and self-reported healthy pouch function were recruited. Patients with chronic pouchitis, Crohn's disease, anastomotic stricture, or indication for IPAA other than ulcerative or indeterminate colitis were excluded. Patients underwent an interview with an abbreviated Rome Questionnaire followed by high-resolution ano-pouch manometry, balloon expulsion test, pouch barostat, and magnetic resonance (MR) defecography. RESULTS: Twenty patients completed all testing. Six patients were excluded from the final analysis due to symptoms suggestive of pouch evacuation disorder on the abbreviated Rome Questionnaire (n = 2), structural abnormality on MR imaging (n = 3), or both (n = 1). Of the remaining 14 patients, mean anal resting pressure during high-resolution manometry was 72 ± 16 mmHg, mean anal squeeze pressure was 247 ± 69 mmHg, and mean pouch-anal gradient during the simulated evacuation was -27 ± 37 mmHg. The meantime to balloon expulsion was 54 seconds. During dynamic MR defecography, the mean descent of ano-pouch junction was 2.6 cm, and mean pouch evacuation was 44.5% and 74.2% pre- and posttoilet phase, respectively. CONCLUSIONS: A substantial proportion of patients with IPAA and self-reported healthy pouch function have anatomic and/or functional abnormalities of the pouch. In asymptomatic IPAA patients with an anatomically normal pouch, we have proposed normal parameters for high-resolution ano-pouch manometry, time to balloon expulsion, pouch barostat, and MR defecography.

Effects of chenodeoxycholate and a bile acid sequestrant, colesevelam, on intestinal transit and bowel function.

BACKGROUND & AIMS: Di-alpha hydroxy bile salt, sodium chenodeoxycholate (CDC), and bile acid binding have unclear effects on colonic transit in health and disease. METHODS: We performed 2 randomized, double-blind, placebo-controlled studies. In healthy volunteers (20 per group), we evaluated the effects of oral placebo, 500 mg, or 1000 mg of CDC (delayed-release, each given for 4 days) on gastrointestinal and colonic transit. A second trial compared the effects of colesevelam (1.875 g, twice daily) versus placebo in 24 patients (12 per group) with diarrhea-predominant irritable bowel syndrome (IBS-D) on transit, daily bowel frequency and consistency, and colonic mucosal permeability. Serum fasting 7alpha-hydroxy-4-cholesten-3-one (7alphaC4) was measured to screen for bile acid malabsorption. Effects of treatments on transit were compared using analysis of covariance with body mass index and 7alphaC4 as covariates. RESULTS: In healthy volunteers, CDC significantly accelerated colonic transit (at 24 and 48 hours, P = .01 and P < .0001, respectively), increased stool frequency and ease of passage (both P < .001), and evacuation (P = .02), and decreased stool consistency (P < .001). Four of the 24 IBS-D patients had increased serum 7alphaC4 levels. In IBS-D, colesevelam modestly affected overall colonic transit (24 h; P = .22). Emptying of the ascending colon took an average of 4 hours longer in patients given colesevelam compared with placebo; treatment effect was associated with baseline serum 7alphaC4 levels (P = .0025). Colesevelam was associated with greater ease of stool passage (P = .048) and somewhat firmer stool consistency (P = .12). No effects on mucosal permeability or safety were identified. CONCLUSIONS: Sodium chenodeoxycholate in health and colesevelam in IBS-D patients have opposite effects on colonic transit and fecal parameters.

Effect of a chloride channel activator, lubiprostone, on colonic sensory and motor functions in healthy subjects.

Lubiprostone, a bicyclic fatty acid chloride channel activator, is efficacious in treatment of chronic constipation and constipation-predominant irritable bowel syndrome. The study aim was to compare effects of lubiprostone and placebo on colonic sensory and motor functions in humans. In double-blind, randomized fashion, 60 healthy adults received three oral doses of placebo or 24 microg lubiprostone per day in a parallel-group, placebo-controlled trial. A barostat-manometry tube was placed in the left colon by flexible sigmoidoscopy and fluoroscopy. We measured treatment effects on colonic sensation and motility with validated methods, with the following end points: colonic compliance, fasting and postprandial tone and motility indexes, pain thresholds, and sensory ratings to distensions. Among participants receiving lubiprostone or placebo, 26 of 30 and 28 of 30, respectively, completed the study. There were no overall effects of lubiprostone on compliance, fasting tone, motility indexes, or sensation. However, there was a treatment-by-sex interaction effect for compliance (P = 0.02), with lubiprostone inducing decreased fasting compliance in women (P = 0.06) and an overall decreased colonic tone contraction after a standard meal relative to fasting tone (P = 0.014), with greater effect in women (P < 0.01). Numerical differences of first sensation and pain thresholds (P = 0.11 in women) in the two groups were not significant. We concluded that oral lubiprostone 24 microg does not increase colonic motor function. The findings of decreased colonic compliance and decreased postprandial colonic tone in women suggest that motor effects are unlikely to cause accelerated colonic transit with lubiprostone, although they may facilitate laxation. Effects of lubiprostone on sensitivity deserve further study.

Effect of 5 days linaclotide on transit and bowel function in females with constipation-predominant irritable bowel syndrome.

BACKGROUND & AIMS: Oral linaclotide, a novel agonist of guanylate cylase-C, stimulates intestinal fluid secretion and transit, and decreases visceral hypersensitivity in animal studies. In healthy volunteers, linaclotide was safe, well tolerated, increased stool frequency, and decreased stool consistency and time to first bowel movement. This randomized, double-blind, placebo-controlled study evaluated the effects of oral linaclotide, 100 and 1000 microg once daily, in 36 women with constipation-predominant irritable bowel syndrome; colonic transit was normal in >50% patients. METHODS: Participants underwent 5-day baseline and 5-day treatment periods; gastrointestinal transit (by validated scintigraphy) and bowel function (by daily diaries) were assessed. Treatment effects were compared using analysis of covariance (baseline colonic transit as covariate) with pairwise comparisons of each dose vs placebo. RESULTS: There was a significant overall treatment effect on ascending colon emptying half-time (P = .015) and overall colonic transit at 48 hours (P = .02) but not overall transit at 24 hours (P = ns), with a significant acceleration by linaclotide 1000 microg vs placebo (P = .004 and P = .01, respectively) but no significant effect of linaclotide 100-microg dose. There were significant overall treatment effects on stool frequency, stool consistency, ease of passage, and time to first bowel movement with a strong dose response for stool consistency (overall, P < .001). No safety issues were identified. CONCLUSIONS: In women with constipation-predominant irritable bowel syndrome, linaclotide 1000 microg once daily significantly accelerated ascending colonic transit and altered bowel function. Further randomized controlled trials of clinical efficacy of linaclotide are warranted.