Randomised clinical trial: the clinical effects of a novel neurokinin receptor antagonist, DNK333, in women with diarrhoea-predominant irritable bowel syndrome

Background Neurokinin receptors may play an important role in the visceral hypersensitivity and exaggerated motor/secretory activity associated with diarrhoea‐predominant irritable bowel syndrome (IBS‐D). Aim To evaluate the effects of DNK333, a novel neurokinin antagonist, in women with IBS‐D. Methods In two consecutive phase II studies, women with IBS‐D were randomised to twice‐daily (b.d.) DNK333 25 mg, DNK333 100 mg or placebo for 2 weeks (Trial 1), or DNK333 25 mg b.d. or placebo for 4 weeks (Trial 2). Primary efficacy variables studied were change from baseline of stool form at week 2, and satisfactory relief of IBS‐related abdominal pain/discomfort and global IBS‐D symptoms. Secondary efficacy variables, pharmacokinetics and safety were also evaluated. Results In total, 315 subjects were randomised. There were no statistically significant differences between treatment groups for the primary efficacy variables. However, analysis of combined data from both trials revealed significant differences favouring DNK333 25 mg over placebo for satisfactory relief of IBS‐related abdominal pain/discomfort and global IBS‐D symptoms. Trends favouring improvement with DNK333 25 mg vs. placebo were seen for all secondary efficacy variables. DNK333 had a safety profile similar to placebo. Conclusions DNK333 25 mg b.d. appears to be effective and well tolerated in women with IBS‐D. Further studies with neurokinin antagonists are warranted.     

Effect of asimadoline, a kappa opioid agonist, on pain induced by colonic distension in patients with irritable bowel syndrome

BACKGROUND: Visceral hypersensitivity plays a major role in irritable bowel syndrome pathophysiology. Opioid kappa receptors on afferent nerves may modulate it and be the target for new irritable bowel syndrome treatments. AIM: This study evaluated the effect of the kappa opioid agonist asimadoline on perception of colonic distension and colonic compliance in irritable bowel syndrome patients. METHOD: Twenty irritable bowel syndrome female patients (Rome II criteria; 40 +/- 13 years) and hypersensitivity to colonic distension (Pain threshold < or = 32 mmHg) were included in a randomized double-blind cross-over trial comparing the effect of a single oral dose of asimadoline 0.5 mg or placebo on sensory thresholds (defined as a constant and sustained sensation) elicited by left colon phasic distension (5 mmHg steps, 5 min) up to a sensation of abdominal pain. Colonic compliance was compared by the slope of the pressure-volume curves. RESULTS: On asimadoline, pain threshold (mean +/- s.d.) (29.8 +/- 7.2 mmHg) was higher than on placebo (26.3 +/- 7.8 mmHg), difference not statistically significant (P = 0.1756, ANOVA). Area under curve of pain intensity rated at each distension step was significantly lower on asimadoline (89.3 +/- 33.9, ANOVA) than on placebo (108.1 +/- 29.7) (P = 0.0411). Thresholds of perception of nonpainful distensions were not altered on asimadoline, as compared with placebo. Colonic compliance was not different on placebo and asimadoline. CONCLUSION: Asimadoline decreases overall perception of pain over a wide range of pressure distension of the colon in irritable bowel syndrome patients, without altering its compliance. These data suggest that further studies should explore the potential benefit of asimadoline in treatment of pain in irritable bowel syndrome patients.     

Clinical trial: the efficacy of alverine citrate/simeticone combination on abdominal pain/discomfort in irritable bowel syndrome ‐ a randomized,double‐blind,placebo‐controlled study

Aliment Pharmacol Ther 31 , 615–624

Summary

Background Alverine citrate and simeticone combination has been used for almost 20 years in irritable bowel syndrome (IBS), but supportive scientific evidence of efficacy was limited. Aim To evaluate the efficacy of alverine citrate and simeticone combination in patients with IBS‐related abdominal pain/discomfort. Methods A total of 412 IBS patients meeting ROME III criteria were included in this double‐blind randomized placebo‐controlled study if their abdominal pain/discomfort intensity was at least 60 mm on a 0–100 mm visual analogue scale (VAS) during a 2‐week run‐in treatment‐free period. Patients were randomly assigned through the use of Interactive Voice Response System to receive either alverine citrate 60 mg with simeticone 300 mg three times daily or matching placebo for 4 weeks. Results The full analysis set included 409 patients (71.4% female: mean age: 46.2 ± 13.9 years). At week 4, alverine citrate and simeticone group had lower VAS scores of abdominal pain/discomfort (median: 40 mm vs. 50 mm, P = 0.047) and higher responder rate (46.8% vs. 34.3%, OR = 1.3; P = 0.01) as compared with placebo group. Patient receiving alverine citrate and simeticone reported greater global symptom improvement compared with those receiving placebo (P = 0.0001). Reported adverse events were similar in both groups. Conclusion Alverine citrate/simeticone combination was significantly more effective than placebo in relieving abdominal pain/discomfort in patients with IBS.     

Symptomatic efficacy of beidellitic montmorillonite in irritable bowel syndrome: a randomized, controlled trial

BACKGROUND: Beidellitic montmorillonite is a purified clay containing a double aluminium and magnesium silicate. AIM: To assess the efficacy and the safety of beidellitic montmorillonite (3 g, t.d. for 8 weeks) in patients with irritable bowel syndrome (IBS). METHODS: A multicentre, double-blind, placebo-controlled, randomized study with parallel groups, was performed in IBS patients selected according to ROME I criteria. Patients were included after a 1-week washout period to confirm that abdominal pain and/or discomfort was rated at least 2 on a 0-4 graded Likert scale. Patients were then randomized and stratified according to their predominant bowel habit profile into three groups. The use of rescue medication was allowed: polyethylene glycol 4000 (10-20 g/day) as a laxative agent in case of stool absence for three consecutive days, phloroglucinol (80 to a maximum of 320 mg/day) as a spasmolytic agent for no more than 8 days. The main end-point was the improvement of abdominal pain and/or discomfort by at least 1 point on the Likert scale. RESULTS: A total of 524 patients constituted the overall intent-to-treat population (ITT), 263 were assessed in the beidellitic montmorillonite group, i.e. 93 diarrhoea-predominant IBS (D-IBS), 83 constipation-predominant IBS (C-IBS), 87 alternating constipation/diarrhoea-IBS (A-IBS); 261 in the placebo group, i.e. 81 D-IBS, 92 C-IBS and 88 A-IBS. Initial analysis in the ITT population demonstrated a higher rate of success with beidellitic montmorillonite (51.7%) when compared with the placebo group (45.2%); however, the difference was not statistically significant. Improvement was significant in C-IBS both in ITT (beidellitic montmorillonite group = 49.4%, placebo group = 31.5%, P < 0.016) and per protocol populations (59.4% vs. 37.8%) (P < 0.01). The time to improvement of abdominal pain and/or discomfort (log Rank test) was also significantly in favour of beidellitic montmorillonite, (P < 0.04). The average number of stools per day was not different from baseline, either in all patients or in C-IBS patients. Spasmolytic and laxative agent intakes were not different between the two groups. Subjective evaluation by patients of treatment efficacy and visual analogue scale test of treatment efficacy by investigators were significantly better in the beidellitic montmorillonite group (P < 0.05). Tolerance of beidellitic montmorillonite was considered optimal without any significant adverse event. CONCLUSIONS: Although pain or discomfort was not significantly improved in the entire IBS population treated with beidellitic montmorillonite in comparison with placebo, this study demonstrates that beidellitic montmorillonite is efficient for C-IBS patients (P < 0.016). This effect of beidellitic montmorillonite on pain cannot be explained by changes in bowel habits. The efficacy of this well-tolerated therapy warrants further confirmatory therapeutic trials in C-IBS patients.     

Update on the Management of Diarrhea‐Predominant Irritable Bowel Syndrome: Focus on Rifaximin and Eluxadoline

Diarrhea‐predominant irritable bowel syndrome (IBS‐D) is one of the most common diagnoses made by gastroenterologists. Current pharmacologic treatments for IBS‐D include fiber supplements, antidiarrheal over‐the‐counter medications, probiotics, antispasmodics, antidepressants, and a 5‐hydroxytryptophan 3 receptor antagonist. All of these options have limited efficacy in managing IBS‐D. Rifaximin, a nonabsorbable antibiotic, has been evaluated in patients with IBS‐D. In two randomized, double‐blind, placebo‐controlled phase III trials evaluating rifaximin 550 mg by mouth 3 times/day for 14 days, the primary efficacy end point was achieved by 9% more patients randomized to the rifaximin group compared with placebo (40.7% vs 31.7%, p<0.001, number needed to treat ~11). The primary efficacy end point was defined as the proportion of patients having adequate relief of global IBS symptoms for at least 2 of the 4 weeks during the primary follow‐up period (weeks 3–6). In the phase III trial examining the efficacy and safety of repeated courses of rifaximin in patients who responded to the initial 2‐week course, rifaximin given for up to two additional courses provided a statistically significant incremental benefit (33% vs 25%, p=0.02). Eluxadoline is a gut‐targeting μ and κ opioid receptor agonist and a δ opioid receptor antagonist. The dual mechanism of eluxadoline may explain the antidiarrheal and abdominal pain‐modulating properties and lack of profound constipation. In two identically designed randomized, double‐blind, placebo‐controlled phase III studies, 10.3% more patients in an eluxadoline 100 mg by mouth twice/day group met the primary efficacy end point during the follow‐up 1–12 week period compared with placebo (p<0.001). The primary efficacy end point was a composite response, defined as improvement in worst abdominal pain and stool consistency at the same time on most (50% or more) days during the follow‐up period. This review evaluates evidence for the use of rifaximin and eluxadoline in patients with IBS‐D. Rifaximin provides an additional modality for the management of IBS‐D patients; it has mild to moderate efficacy similar to other currently available treatment options. Rifaximin is relatively safe, lacks significant drug‐drug interactions, and can be used for up to two additional retreatment courses. This may make rifaximin a possible initial or second‐line treatment option. Eluxadoline can also offer relief to patients with IBS‐D. While effective, because of several limitations, including drug‐drug interactions and drug disease contraindications, as well as current lack of clinical experience, it may be tried as a second‐ or third‐line agent.     

A dose-ranging, placebo-controlled, randomized trial of alosetron in patients with functional dyspepsia

BACKGROUND: Functional dyspepsia is characterized by upper abdominal pain or discomfort. AIM: To assess the benefit of the 5-HT3-receptor antagonist alosetron in a pilot, dose-ranging, placebo-controlled, multicentre, randomized clinical trial. METHODS: A total of 320 functional dyspepsia patients received placebo (n=81), or alosetron 0.5 mg b.d. (n=77), 1.0 mg b.d. (n=79) or 2.0 mg b.d. (n=83) for 12 weeks, followed by 1 week of follow-up. Primary efficacy was the 12-week average rate of adequate relief of upper abdominal pain or discomfort. Secondary endpoints assessed pain and upper gastrointestinal symptoms. RESULTS: Twelve-week average rates of adequate relief of pain or discomfort were 46% (95% CI: 37-54%), 55% (95% CI: 46-63%), 55% (95% CI: 47-64%) and 47% (95% CI: 38-55%) in the placebo, 0.5 mg, 1.0 mg and 2.0 mg alosetron groups, respectively. Alosetron 0.5 mg or 1.0 mg showed potential benefit over placebo for early satiety and postprandial fullness. Females showed greater responses compared to males. Patients with adequate relief had significantly (P < 0.001) greater reductions in severity and frequency of functional dyspepsia symptoms than those without adequate relief. Constipation was the most commonly reported adverse event. CONCLUSIONS: Alosetron showed potential benefit in relieving functional dyspepsia symptoms compared to placebo. Patients with adequate relief of upper abdominal pain or discomfort showed improvements in multiple functional dyspepsia symptoms.     

Clinical trial: renzapride therapy for constipation-predominant irritable bowel syndrome--multicentre, randomized, placebo-controlled, double-blind study in primary healthcare setting

Background  Relatively few pharmacological treatment options are available for treating patients with irritable bowel syndrome. New and effective medicines are urgently required.
Aim  To identify an appropriate dosage of renzapride (a 5-HT₄ receptor full agonist/5-HT₃ receptor antagonist) to treat abdominal pain/discomfort in patients with constipation-predominant irritable bowel syndrome.
Methods  In this randomized, placebo-controlled, phase IIb study in the primary care setting, men and women were randomized to placebo or renzapride (1, 2 or 4 mg/day) for 12 weeks. The primary outcome measure was patient self-assessed relief of abdominal pain/discomfort during weeks 5–12. Secondary efficacy measures included patients' assessment of their bowel habits, stool consistency and quality of life.
Results  Although there were no statistically significant differences between renzapride and placebo for relief from abdominal pain/discomfort, responder rates in the renzapride treatment groups increased dose dependently, with the 4 mg/day group being consistently numerically greater than placebo. Importantly, a larger numerical treatment difference vs. placebo was observed in women (8% and 12% respectively). Statistically significant improvements in bowel movement frequency and stool consistency were observed in the 4 mg/day group relative to placebo. Renzapride was well tolerated at all doses.
Conclusions  This study confirms the gastrointestinal prokinetic effects of renzparide. The data also suggested a potentially beneficial effect on abdominal pain/discomfort in women with constipation-predominant irritable bowel syndrome.     

Randomised clinical trial: Bifidobacterium bifidum MIMBb75 significantly alleviates irritable bowel syndrome and improves quality of life--a double-blind, placebo-controlled study

Aliment Pharmacol Ther 2011; 33: 1123–1132

Summary

Background Recent research suggests that an imbalance of the intestinal microbiota and a dysfunctional intestinal barrier might trigger irritable bowel syndrome (IBS). As probiotics have been reported to restore the intestinal microbiota and the gut barrier, the therapeutic potential of probiotics within IBS became of strong interest. Aim To assess the efficacy of Bifidobacterium bifidum MIMBb75 in IBS. Methods A total of 122 patients were randomised to receive either placebo (N = 62) or MIMBb75 (N = 60) once a day for 4 weeks. The severity of IBS symptoms was recorded daily on a 7‐point Likert scale. Results MIMBb75 significantly reduced the global assessment of IBS symptoms by ?0.88 points (95% CI: ?1.07; ?0.69) when compared with only ?0.16 (95% CI: ?0.32; 0.00) points in the placebo group (P < 0.0001). MIMBb75 also significantly improved the IBS symptoms pain/discomfort, distension/bloating, urgency and digestive disorder. The evaluation of the SF12 sum scores showed a significant gain in quality of life within the bifidobacteria group. Furthermore, adequate relief was reported by 47% of the patients in the bifidobacteria and only by 11% of the patients in the placebo group (P < 0.0001). Overall responder rates were 57% in the bifidobacteria group but only 21% in the placebo group (P = 0.0001). MIMBb75 was well tolerated and adverse events were not different from placebo. Conclusions Bifidobacterium bifidum MIMBb75 effectively alleviates global IBS and improves IBS symptoms simultaneously with an improvement of quality of life. Considering the high efficacy of MIMBb75 in IBS along with the good side‐effect profile, MIMBb75 is a promising candidate for IBS therapy.

     

Clinical trial: lubiprostone in patients with constipation-associated irritable bowel syndrome – results of two randomized, placebo-controlled studies

Background Effective treatments for irritable bowel syndrome with constipation (IBS‐C) are lacking. Aim To assess the efficacy and safety of lubiprostone in IBS‐C. Methods A combined analysis was performed among 1171 patients with a Rome II diagnosis of IBS‐C in two phase‐3 randomized trials of lubiprostone 8 mcg vs. placebo twice daily for 12 weeks. Using a balanced seven‐point Likert scale ranging from significantly relieved (+3), to significantly worse (?3), patients responded on their electronic diary to the question: ‘How would you rate your relief of IBS symptoms over the past week compared to how you felt before you entered the study?’. The primary efficacy endpoint was the percentage of overall responders. Results Using an intent‐to‐treat analysis with last observation carried forward, a significantly higher percentage of lubiprostone‐treated patients were considered overall responders compared with those treated with placebo (17.9% vs. 10.1%, P = 0.001). Patients treated with lubiprostone reported a similar incidence of adverse events to those treated with placebo. Conclusions The percentage of overall responders based on patient‐rated assessments of IBS‐C symptoms was significantly improved in patients treated with lubiprostone 8 mcg twice daily compared to those treated with placebo. Lubiprostone was well tolerated with a favourable safety profile.     

Asimadoline, a kappa-opioid agonist, and satiation in functional dyspepsia

Background  Asimadoline, a kappa-opioid agonist, reduces visceral sensitivity in experimental animal models and may decrease satiation and postprandial fullness in healthy individuals. However, its effect on satiation in functional dyspepsia is unclear, and any symptom benefit has not been explored.
Aim  To evaluate the effects of asimadoline on satiation volume and postchallenge symptoms in functional dyspepsia.
Methods  A randomized, double-blind trial evaluated gastric satiation and symptoms before and after 8 weeks of asimadoline 0.5 mg ( n  = 13) or 1.0 mg ( n  = 13) or placebo ( n  = 14) b.d. in patients with functional dyspepsia (Rome II). Gastrointestinal Symptom Rating Scale and Nepean Dyspepsia Index were used to assess symptoms during the 8-week treatment.
Results  Over 8 weeks of treatment, asimadoline had no significant effect on maximum-tolerated volume or aggregate symptom score with nutrient drink challenge, and on the mean of the total daily symptom severity score compared to placebo. In a post hoc analysis, asimadoline 0.5 mg significantly increased the maximum-tolerated volume (1217 mL ± 90.2) compared to placebo (807 mL ± 111.8) in patients with higher postprandial fullness scores ( P  = 0.01).
Conclusion  Asimadoline overall did not significantly alter maximum-tolerated volume, symptoms postnutrient challenge or symptoms over 8 weeks in functional dyspepsia.     

Review article: the treatment of functional abdominal bloating and distension

Aliment Pharmacol Ther 2011; 33: 1071–1086

Summary

Background Abdominal bloating and distension are common symptoms in patients with functional gastrointestinal disorders (FGIDs), however, relatively little is known about their treatment. Aim To review the treatment trials for abdominal bloating and distension. Methods A literature review in Medline for English‐language publications through February 2010 of randomised, controlled treatment trials in adults. Study quality was assessed according to Jadad’s score. Results Of the 89 studies reviewed, 18% evaluated patients with functional dyspepsia, 61% with irritable bowel syndrome (IBS), 10% with chronic constipation and 10% with other FGIDs. No studies were conducted in patients diagnosed with functional abdominal bloating. The majority of trials investigated the efficacy of prokinetics or probiotics, although studies are heterogeneous with respect to diagnostic criteria and outcome measures. In general, bloating and/or distension were evaluated as secondary endpoints or as individual symptoms as part of a composite score rather than as primary endpoints. A greater proportion of IBS patients with constipation reported improvement in bloating with tegaserod vs. placebo (51% vs. 40%, P < 0.0001) and lubiprostone (P < 0.001). A greater proportion of nonconstipating IBS patients reported adequate relief of bloating with rifaximin vs. placebo (40% vs. 30%, P < 0.001). Bloating was significantly reduced with the probiotics, Bifidobacterium infantis 35624 (1 × 10⁸ dose vs. placebo: ?0.71 vs. ?0.44, P < 0.05) and B. animalis (live vs. heat‐killed: ?0.56 ± 1.01 vs. ?0.31 ± 0.87, P = 0.03). Conclusions Prokinetics, lubiprostone, antibiotics and probiotics demonstrate efficacy for the treatment of bloating and/or distension in certain FGIDs, but other agents have either not been studied adequately or have shown conflicting results.

     

Clinical trial: the glucagon-like peptide-1 analogue ROSE-010 for management of acute pain in patients with irritable bowel syndrome: a randomized, placebo-controlled, double-blind study

Background  There is currently no treatment available to manage acute pain attacks in IBS patients regardless of subtype.
Aims  To evaluate efficacy and safety of the GLP-1 analogue ROSE-010 in patients with irritable bowel syndrome (IBS) through a randomized, double-blind, placebo-controlled study.
Methods  Eligible patients ( n  = 166) meeting Rome II criteria were randomly assigned to receive single subcutaneous injections of ROSE-010 100 μg, 300 μg and placebo in a cross-over design. Safety was assessed from spontaneously reported adverse events and measurement of vital signs. Patient-rated pain relief and intensity were measured on a 100-mm visual analogue scale. The primary efficacy variable was proportion of patients with >50% maximum total pain relief response from 10 to 60 min after treatment. Secondary endpoints included the maximum summed pain intensity difference, time to meaningful pain relief and patient ratings of satisfaction with treatment.
Results  Twice as many patients were responders in the primary efficacy endpoint after both ROSE-010 injections compared to placebo (24% P  = 0.011, 23% P  = 0.005, and 12% after 300 μg, 100 μg and placebo injections, respectively). Similar results were obtained for the proportion of patients with total pain intensity response. Times to meaningful and total pain relief were shorter for both doses of ROSE-010 compared with placebo. Compared with placebo, more patients ( P  < 0.05) were satisfied with ROSE-010 and considered ROSE-010 better than previous IBS medications used.
Conclusion  ROSE-010 was well tolerated and provided fast and effective relief of acute pain attacks on demand in IBS patients.     

Effects of asimadoline,a kappa-opioid agonist,on satiation and postprandial symptoms in health

AIM: To evaluate the effect of single administrations of asimadoline, a kappa-opioid agonist, on satiation volume, postprandial symptoms and gastric volumes. METHODS: Healthy subjects received oral placebo, or 0.5 or 1.5 mg asimadoline in a randomized, double-blind fashion 1 h prior to testing. We assessed effects on the volume of Ensure to achieve full satiation and postprandial symptoms 30 min after meal, and on gastric volume (fasting and postprandial) measured by 99mTc-single photon emission tomography (SPECT) imaging. RESULTS: Thirteen healthy subjects were studied in each treatment arm. Compared to placebo, asimadoline 0.5 mg decreased postprandial fullness (P = 0.027) without affecting the volume ingested at full satiation (P = 0.6). Asimadoline 1.5 mg decreased satiation during meal, allowing increased satiation volumes (P = 0.008) and tended to decrease postprandial fullness (P = 0.067), despite higher volumes ingested. There was a significant treatment-gender interaction in the effect of asimadoline on gastric volumes (P < 0.05). Asimadoline 0.5 mg (not 1.5 mg) increased fasting (P = 0.047) and postprandial (P = 0.009) gastric volumes in females but decreased fasting volumes in males (P = 0.008). The effect of asimadoline on gastric volume did not explain the effect observed on satiation volume (P = 0.371) or postprandial fullness (P = 0.399). CONCLUSION: A single oral administration of asimadoline decreases satiation and postprandial fullness in humans independently of its effects on gastric volume.     

Meta‐analysis: factors affecting placebo response rate in the irritable bowel syndrome

Aliment Pharmacol Ther 2010; 32: 144–158

Summary

Background Irritable bowel syndrome (IBS) is a functional disorder of the gastrointestinal tract with a significant placebo response. Aim To conduct a systematic review and meta‐analysis examining the magnitude of placebo response rate in treatment trials for IBS. Methods MEDLINE, EMBASE and the Cochrane central register of controlled trials were searched to identify randomized controlled trials (RCTs) comparing pharmacological therapies with placebo in adult IBS patients. Studies reported either global assessment of IBS symptom cure or improvement or abdominal pain cure or improvement. Data were extracted as intention‐to‐treat analyses with drop‐outs assumed to be treatment failures and pooled using a random‐effects model. Proportion of placebo patients experiencing symptom improvement or resolution was reported with a 95% confidence interval (CI). Effect of trial characteristics on magnitude of placebo response was examined. Results In all, 73 RCTs were eligible, including 8364 patients with IBS allocated to placebo. Pooled placebo response rate across all RCTs was 37.5% (95% CI 34.4–40.6%). Rates were higher in European RCTs, RCTs that used physician‐reported outcomes and RCTs using shorter duration of therapy. Conclusions Placebo response rates across RCTs of pharmacological therapies in IBS were high. Future research should identify patient characteristics predicting placebo response.     

Alverine citrate fails to relieve the symptoms of irritable bowel syndrome: results of a double-blind,randomized, placebo-controlled trial

BACKGROUND: Alverine citrate has been used in the treatment of irritable bowel syndrome for many years. AIMS: To compare the efficacy and safety of a new formulation of alverine citrate, a 120-mg capsule, with placebo given three times daily for 12 weeks. METHODS: One hundred and seven patients with irritable bowel syndrome were entered into this three-centre, double-blind, randomized, placebo-controlled, parallel group trial. The primary end-point was relief of abdominal pain indicated by improvement in the scores for severity and frequency. Secondary efficacy variables included scores for other clinical symptoms and for overall well-being. RESULTS: The severity and frequency of abdominal pain improved in 66% and 68% of patients treated with alverine citrate vs. 58% and 69% of the placebo group, but these differences were not significant. The mean percentage reduction in the scores for abdominal pain from baseline to the final assessment, although greater in the alverine citrate group (43.7%) compared with the placebo group (33.3%), was not statistically significant. CONCLUSIONS: Alverine citrate is no better than placebo at relieving the symptoms of irritable bowel syndrome. Future trials should be designed to take into account the high and persistent placebo response seen in this condition.     

Systematic review: the efficacy of treatments for irritable bowel syndrome--a European perspective

BACKGROUND: Irritable bowel syndrome (IBS) is a common, chronic disorder, characterized by abdominal pain/discomfort, bloating and altered bowel habit. AIM: To conduct a systematic evidence-based review of pharmacological therapies currently used, or in clinical development, for the treatment of IBS in Europe. The safety and tolerability of these therapies are the subject of an accompanying review. METHODS: A literature search was completed for randomized controlled studies which included adult patients with IBS and an active or placebo control, assessed IBS symptoms, and were published in English between January 1980 and June 2005. The level of evidence for efficacy was graded according to the quality of the trial design and the study outcome. RESULTS: There is some evidence for improvement of individual IBS symptoms with antidiarrhoeals (diarrhoea), antispasmodics (abdominal pain/discomfort), bulking agents (constipation), tricyclic antidepressants (abdominal pain/discomfort) and behavioural therapy. In contrast, there is strong evidence for the improvement of global IBS symptoms with two new serotonergic agents: the 5-HT4 selective agonist tegaserod (IBS with constipation) and the 5-HT3 antagonist alosetron (IBS with diarrhoea). Further data are required for the 5-HT3 antagonist, cilansetron, and the mixed 5-HT3 antagonist/5-HT4 agonist renzapride before their utility in IBS can be appraised. CONCLUSIONS: There is limited evidence for the efficacy, safety and tolerability of therapies currently available in Europe for the treatment of IBS. Overall, there is an absence of pharmacological agents licensed specifically for the treatment of IBS subtypes, and new agents are awaited in Europe that will allow changes in clinical practice to focus on and improve global IBS symptoms.     

Effect of mesalazine on mucosal immune biomarkers in irritable bowel syndrome: a randomized controlled proof-of-concept study

Background  Intestinal immune infiltration contributes to symptoms in patients with irritable bowel syndrome (IBS).
Aim  To assesses the effect of mesalazine (mesalamine) on mucosal immune cells in patients with IBS, through a pilot study.
Methods  A randomized, double-blind, placebo-controlled trial in 20 patients with IBS in tertiary care setting. Patients were randomized to receive placebo or 800 mg mesalazine three times daily for 8 weeks. The primary endpoint was a significant reduction in total colonic immune cells on biopsies obtained at the end of treatment compared to baseline. Secondary endpoints included effects on subsets of immune cells, inflammatory mediators and symptom severity. Intention-to-treat analysis was performed.
Results  Mesalazine markedly reduced immune cells as compared with placebo ( P  = 0.0082); this effect was ascribed to a marked inhibition of mast cells ( P  = 0.0014). Mesalazine significantly increased general well-being ( P  = 0.038), but had no significant effects on abdominal pain ( P  = 0.084), bloating ( P  = 0.177) or bowel habits. No serious drug-related adverse events were reported during the study.
Conclusions  Mesalazine is an effective and safe approach to reduce mast cell infiltration and may improve general well-being in patients with IBS. These results support the hypothesis that immune mechanisms represent potential therapeutic targets in IBS.     

Mesalazine (5-aminosalicylic acid) alters faecal bacterial profiles, but not mucosal proteolytic activity in diarrhoea-predominant irritable bowel syndrome

Aliment Pharmacol Ther 2011; 34: 374–383

Summary

Background Imbalances in gut luminal bacteria may contribute to the pathogenesis of irritable bowel syndrome (IBS). Aim To explore select bacteriological and anti‐inflammatory effects of mesalazine (mesalamine; 5‐aminosalicylic acid or 5ASA) and their relation to potential therapeutic effects in IBS. Methods Prospective pilot study of 12 women with diarrhoea‐predominant IBS. Patients received oral mesalazine (1.5 g b.d.) for 4 weeks followed by a 4‐week washout phase. Molecular profiling of stool bacterial communities and IBS symptoms were assessed before, during and after mesalazine treatment. Colonic mucosal biopsies were assessed for proteolytic activity. Qualitative and quantitative effects of mesalazine on stool microbiota, mucosal proteolytic activity and IBS symptoms were assessed. Results Faecal bacteria decreased by 46% on mesalazine treatment (P = 0.014), but returned to baseline during washout. Firmicutes and Bacteroidetes represented 95% of identified phylotypes, with a trend towards an increase in the proportion of Firmicutes at week 4 in symptomatic responders [median (IQR) 14% (49) increase] compared with nonresponders [median 5% (11) decrease, P = 0.088]. Rectosigmoid mucosal proteolytic activity did not change between baseline and treatment [median 23.2 (17.9) vs. 19.5 (46.7) mU activity/mg tissue, P = 0.433]. Eight of 12 (67%) patients responded favourably to mesalazine based on a global relief questionnaire, with significant decreases in days with discomfort and increases in bowel movement satisfaction. Conclusions Mesalazine treatment is associated with a decrease in faecal bacteria abundance and rebalancing of the major constituents of the microbiota. Further study of the bacteriological and anti‐inflammatory properties of mesalazine in IBS is warranted.     

Clinical trial: effect of active lactic acid bacteria on mucosal barrier function in patients with diarrhoea-predominant irritable bowel syndrome

Background The intestinal permeability is increased in patients with diarrhoea‐predominant irritable bowel syndrome (D‐IBS). Aim To determine the possible efficacy of lactic acid bacteria on the increased intestinal permeability in D‐IBS. Methods Treatment was employed for 4 weeks in a randomized single blind placebo controlled study with 30 D‐IBS patients. Patients were given either probiotic fermented milk (Streptococcus thermophilus, Lactobacillus bulgaricus, Lactobacillus acidophilus and Bifidobacterium Longum) or milk beverage containing no bacteria. The clinical symptoms were scored and intestinal permeability was measured by a triple sugar test before and after treatment. Results Small bowel permeability was measured as the ratio of lactulose and mannitol recovery and colonic permeability was measured as the total mass of sucralose excretion (mg). After probiotics treatment, small bowel permeability decreased significantly from 0.038 (0.024) at baseline to 0.023 (0.020) (P = 0.004), the proportion of patients with increased small bowel permeability was lower than baseline (28.6% vs. 64.3%, P = 0.023). However, colonic permeability improved neither in the probiotics group nor in the placebo group at week 4. Treatment with probiotics significantly decreased the mean global IBS scores compared with the baseline scores (9.62 ± 1.05 vs. 7.64 ± 1.24, P < 0.001). Conclusion Short‐term active lactic acid bacteria treatment for D‐IBS improved mucosal barrier function.     

Improvement in pain and bowel function in female irritable bowel patients with alosetron, a 5-HT3 receptor antagonist

BACKGROUND: No currently available treatment provides consistent relief of irritable bowel syndrome. Colonic sensory and motor function are modulated partly through 5HT3-receptors. AIM: To evaluate effects of the 5HT3-receptor antagonist, alosetron, in irritable bowel syndrome. METHODS: Randomized, double-blind, placebo-controlled, dose-ranging (1, 2, 4, 8 mg b.d. alosetron), 12-week trial in 370 patients with diarrhoea-predominant or alternating constipation and diarrhoea irritable bowel syndrome. Weekly measurement of adequate relief was the key end-point; other irritable bowel syndrome symptoms were collected daily using an electronic phone system. RESULTS: Alosetron (1 mg or 2 mg b.d.) significantly (P < 0.05 vs. placebo) increased the proportion of females, but not males, reporting adequate relief. Stool consistency, frequency and percentage days with urgency improved over placebo (P < 0.05) within the first month with all doses of alosetron, and persisted throughout the trial with all doses in female patients. With 1 mg b.d. alosetron, females had improved stool consistency and urgency within the first week, and adequate relief and improved stool frequency within the first 2 weeks. There was no consistent improvement in bowel function among male patients. CONCLUSION: In female irritable bowel syndrome patients with predominant diarrhoea or alternating constipation and diarrhoea, alosetron is effective in treatment of abdominal pain and discomfort and bowel-related symptoms.