A 54-year-old woman with constipation-predominant irritable bowel syndrome.
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Biomedical subjects
Anthony J Lembo
Publications and source records attributed to Anthony J Lembo.
Investigating placebo effects in irritable bowel syndrome: a novel research design.
Little is known about placebo effects with scientific precision. Poor methodology has confounded our understanding of the magnitude and even the existence of the placebo effect. Investigating placebo effects presents special research challenges including: the design of appropriate controls for studying placebo effects including separating such effects from natural history and regression to the mean, the need for large sample sizes to capture expected small effects, and the need to understand such potential effects from a patient's perspective. This article summarizes the methodology of an ongoing NIH-funded randomized controlled trial aimed at investigating whether the placebo effect in irritable bowel syndrome (IBS) exists and whether the magnitude of such an effect can be manipulated to vary in a manner analogous to "dose dependence." The trial also uses an innovative combination of quantitative and qualitative methods.
Acupuncture Therapy↗
Current gut-directed therapies for irritable bowel syndrome.
Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder that can present with a wide array of symptoms that make treatment difficult. Current therapies are directed at relieving symptoms of abdominal pain or discomfort, bloating, constipation, and diarrhea. Pharmacologic agents used to treat IBS-associated pain include myorelaxants, peppermint oil, and peripherally acting opiates. Dicyclomine and hyoscyamine, the two myorelaxants available in the United States, have not been proven effective in reducing abdominal pain in patients with IBS. The efficacy of peppermint oil is debated, but methodological problems with existing studies preclude definitive judgment. Loperamide is ineffective for relief of abdominal pain. For IBS patients with excessive abdominal bloating, a small number of studies suggest that bacterial eradication with gut-directed antibiotics and bacterial reconstitution with nonpathogenic probiotics may reduce flatulence. For constipation-predominant (C-IBS) symptoms, current treatment options include fiber supplementation, polyethylene glycol, and tegaserod. Soluble fibers (ispaghula, calcium polycarbophil, psyllium) are more effective than insoluble fibers (wheat bran, corn fiber) in alleviating global symptoms and relieving constipation, although fiber in general has marginal benefit in treatment of overall IBS symptoms. Polyethylene glycol increases bowel frequency in chronic constipation, but its overall efficacy against IBS is unclear. Tegaserod, a 5-HT(4) agonist, demonstrates superiority over placebo in improving bowel frequency and stool consistency and alleviating abdominal pain and bloating in women with C-IBS. Overall global symptoms are modestly improved with tegaserod when compared with placebo. Additional agents under investigation for C-IBS include the ClC(2) chloride channel opener lubiprostone, mu-opioid receptor antagonist alvimopan, and 5-HT(4) agonist renzapride. For diarrhea-predominant (D-IBS) symptoms, available therapies include loperamide, alosetron, and clonidine. Alosetron, a 5-HT(3) antagonist, is superior to placebo for reducing bowel frequency, improving stool consistency, and relieving abdominal pain in women with D-IBS. However, alosetron is available under a restricted license because of concerns for ischemic colitis and severe constipation necessitating colectomy. Clonidine may be helpful in alleviating global symptoms for D-IBS patients.
Journal Article↗
Visceral hypersensitivity in noncardiac chest pain.
Visceral hypersensitivity is a common cause of NCCP. Mechanoreceptors appear to be important in the pathophysiology of NCCP, although chemoreceptors also appear to play a significant role. The processing of visceral information and possibly the development of central sensitization may be important in NCCP, although the pathophysiology of NCCPremains poorly understood.
Chest Pain↗
Effect of alosetron on bowel urgency and global symptoms in women with severe, diarrhea-predominant irritable bowel syndrome: analysis of two controlled trials.
BACKGROUND & AIMS: The aim of this study was to assess the effect of alosetron on bowel urgency and irritable bowel syndrome (IBS) global improvement in diarrhea-predominant IBS (D-IBS). METHODS: Women with a lack of satisfactory bowel urgency control at least 50% of the time during screening were randomized to receive alosetron 1 mg (n = 246) or placebo (n = 246) twice daily. The primary end point was the percentage of days with satisfactory control of bowel urgency. The response rate for the IBS global improvement scale (GIS) was a secondary end point. GIS responders were patients who recorded either moderate or substantial improvement in IBS symptoms relative to the way they felt before entering the study. Other end points included improvement in stool frequency, stool consistency, and percentage of days with incomplete evacuation. Further analyses were performed on a subset of patients who had at least 10 of 14 days during screening (>/=71% of days) with a lack of satisfactory control of bowel urgency. RESULTS: Patients had severe chronic IBS symptoms, and 89% of patients had D-IBS. Alosetron resulted in a greater percentage of days with satisfactory control of urgency compared with placebo (69% vs. 56%, respectively, P < 0.001). Greater percentages of alosetron-treated patients were GIS responders at 4, 8, and 12 weeks compared with placebo (59% vs. 41%, 63% vs. 41%, and 68% vs. 46%, respectively, P < 0.001). Patients with more frequent urgency had similar results. Constipation occurred in 28% and 9% of subjects in the alosetron- and placebo-treated groups, respectively. No cases of ischemic colitis were reported. CONCLUSIONS: Alosetron effectively manages bowel urgency and improves global symptoms in women with severe chronic D-IBS.
Adult↗
Effect of tegaserod in chronic constipation: a randomized, double-blind, controlled trial.
BACKGROUND AND AIMS: Chronic constipation is a common gastrointestinal disorder. The aim of this study was to evaluate the efficacy, safety, and tolerability of tegaserod, a serotonin subtype 4 receptor partial agonist in patients with chronic constipation. METHODS: This was a randomized, double-blind, placebo-controlled study. After a 2-week baseline, patients received tegaserod 2 mg twice daily (n = 450), tegaserod 6 mg twice daily (n = 451), or placebo (n = 447) for 12 weeks, followed by a 4-week withdrawal period. Responders were those patients having been treated for at least 7 days with an increase of > or =1 complete spontaneous bowel movement/week vs. baseline during weeks 1-4 (primary variable) and weeks 1-12 (secondary variable). Other secondary variables included patient assessment of constipation symptoms (number of bowel movements, stool form, abdominal bloating/distention, straining, and abdominal pain/discomfort), and global assessment of constipation and bowel habits. RESULTS: Responder rates for complete spontaneous bowel movement during weeks 1-4 were significantly greater ( P < 0.0001) in the tegaserod 2 mg twice daily (41.4%) and 6 mg twice daily groups (43.2%) vs. placebo (25.1%). This effect was maintained over 12 weeks. Statistically significant improvements over placebo were observed across the majority of secondary variables for both tegaserod doses. No rebound effect was observed after treatment withdrawal. Tegaserod was well tolerated; headache and nasopharyngitis, the most frequent adverse events, were more common in the placebo group than in either tegaserod group. CONCLUSIONS: Over 12 weeks, tegaserod treatment produced significant improvements in chronic constipation symptoms and was also safe and well tolerated.
Chronic Disease↗
Neurotrophin-3 improves functional constipation.
OBJECTIVE: Neurotrophin-3 (NT-3) is a neurotrophic factor involved in the growth, development, and function of the nervous system. In preliminary studies, s.c. recombinant methionyl-human NT-3 enhanced transit throughout the GI tract and increased stool frequency in normal and constipated subjects. Our aim was to assess 1) the dose-related effects of NT-3 on bowel function, colon transit, and symptoms of chronic constipation, and 2) its safety. METHODS: This was a double-blind, randomized, placebo-controlled phase II study. A total of 107 patients with a diagnosis of functional constipation (Rome II criteria) were randomized to receive 4 wk of double blind, s.c. injections of either placebo, 3 mg, or 9 mg NT-3 once per week (qW) or three times per week (TTW); or 9 mg NT-3 TTW for 1 wk, then qW. The primary endpoint was the change in number of spontaneous, complete bowel movements per week. Colon transit was assessed before and at end of treatment. RESULTS: Compared with placebo, patients who received 9 mg NT-3 TTW showed significant increases in frequency of spontaneous, complete bowel movements and total bowel movements, as well as dose-related softening of stool and improved ease of passage. The number of days per week without a bowel movement also decreased, colon transit improved, as did constipation-related symptoms. Weekly dosing was ineffective. Transient injection-site reactions, seen in one third of patients receiving NT-3 TTW, were the most frequent adverse event. CONCLUSIONS: NT-3, administered TTW, increased stool frequency, enhanced colon transit, and improved symptoms of chronic constipation. NT-3 seems to be a novel, safe, and effective agent for the treatment of functional constipation.
Adolescent↗