Current and emerging drug options in the treatment of diarrhea predominant irritable bowel syndrome

Herbal placebo response in clinical trials on irritable bowel syndrome: a systematic review and meta-analysis

AIM OF THE STUDY

To systematically evaluate the herbal placebo response in randomized controlled trials (RCTs) of herbal medicine on irritable bowel syndrome (IBS).

MATERIALS AND METHODS

We searched for RCTs with herbal placebo groups for IBS in PubMed, EMBASE, the Cochrane Library, the China National Knowledge Infrastructure (CNKI), the Wan Fang database and Sinomed database from 31 January 1994 to November 2023, and the quality of the literature was evaluated by the Cochrane risk of bias assessment criteria. The primary outcome indicators were response rate, abdominal pain and stool improvement rate, which were analyzed by single-group rate meta-analysis. Secondary outcomes were analyzed in subgroups based on diagnostic criteria, duration of treatment, subtype, research locations, placebo form, and presence of herbal ingredients to look for factors affecting respond rate.

RESULTS

The study included 24 papers, involving a total of 2,596 patients. Of these, 1151 IBS patients were treated with the herbal placebo. The placebo response rate in IBS patients in the herbal placebo group was 37% (P < 0.01,I2 = 75%). A total of 287 patients in five studies were given the herbal placebo, and the improvement rate of abdominal pain was 29% (P = 0.83, I2 = 0%). Four studies enrolled a total of 212 patients with IBS who received herbal placebo, and the stool improvement rate was 46% (P = 0.02 < 0.05, I2 = 71%). The research locations and treatment duration were sources of heterogeneity (P < 0.05).

CONCLUSION

There is a significant herbal placebo response in patients with IBS. Different research locations and treatment durations are major sources of heterogeneity that may affect IBS patient response rates. The addition of a low dose of herbal ingredients when simulating an herbal placebo does not exaggerate the therapeutic effect of the placebo. There is a lack of uniformity and standardization in the preparation and evaluation of herbal placebos.

Different therapies of Chinese herbal medicine for diarrhea-predominant irritable bowel syndrome: A network meta-analysis of double-blinded, placebo-controlled trials

ETHNOPHARMACOLOGICAL RELEVANCE

Shuganjianpi Therapy (SGJP), Jianpi Therapy (JP), Shugan Therapy (SG), Jianpiwenshen Therapy (JPWS), and Shuganjianpiwenshen Therapy (SGJPWS), consisting of formulas from Chinese herbal medicine (CHM), have been tremendously applied to irritable bowel syndrome (IBS). However, it remains uncertain when exploring the preferable option among different CHM therapies for diarrhea-predominant irritable bowel syndrome (IBS-D).

AIM OF THE STUDY

To compare and rank the efficacy and safety of different CHM therapies for IBS-D.

MATERIALS AND METHODS

We searched randomized, double-blinded, placebo-controlled trials through mainstream databases from their inception to October 31, 2022. Eligible randomized controlled trials (RCTs) applied one of the CHM therapies as the experimental group and placebo as the control group. Two authors independently extracted data into a form and evaluated the quality of the retrieved articles by the Cochrane Risk of Bias Tool. At least one of the following outcomes was assessed: Serotonin, Neuropeptide Y (NPY), Incidence of Adverse Events (AE), and Irritable Bowel Syndrome-Severity Scoring System (IBS-SSS) with its subscales of Severity of Abdominal Pain (SAP), Frequency of Abdominal Pain (FAP), Severity of Abdominal Distension (SAD), Dissatisfaction with Bowel Habits (DBH), and Interference with Quality of Life (IQOL). A Bayesian network meta-analysis on a random-effect model was conducted using R 4.2.2 software.

RESULTS

1367 records were retrieved from databases in an initial search. Fourteen studies involving six interventions with 2248 participants were identified. Provided pairwise comparisons, the surface under the cumulative ranking curve (SUCRA) ranking, and cluster analysis, JPWS was the best option for ameliorating clinical symptoms simultaneously, which included IBS-SSS, SAP, FAP, SAD, DBH, and IQOL. As for AE, JPWS contributed to fewer adverse events than others as well. In respect of serum indicators, we noticed the dominance of SGJP in regulating both serotonin and NPY.

CONCLUSIONS

JPWS and SGJP were the most prominent CHM therapies for IBS-D in terms of clinical symptoms, including abdominal pain, distension, bowel habits, and improvement of quality of life. The effect of JP and SG for IBS-D required further investigation. As a potential candidate, SGJP may well treat IBS-D by mediating dysmotility, visceral hypersensitivity, and the gut-brain axis with an increase of NPY and a reduction of serotonin. For safety, JPWS was ideal for the fewest adverse events in the treatment of IBS-D. On account of a small sample size and possible geographical publication bias, more double-blinded and placebo-controlled trials with larger samples worldwide would be necessary for strengthening current evidence.

Potential of natural products in the treatment of irritable bowel syndrome

BACKGROUND

Irritable bowel syndrome (IBS) is a kind of functional bowel disease that is characterized by bellyache, abdominal distension, and diarrhea. Although not life-threatening, IBS has a long course and recurrent attacks and seriously affects the life quality of patients. Current drugs for treating IBS possess remarkable limitations, such as limited efficacy and severe adverse reactions. Therefore, developing novel medications to treat IBS is quite essential, and natural products may be a substantial source.

PURPOSE

This is the first systematic review elaborating the recent advancement of natural products as potential drugs for the therapy of IBS.

METHODS

A comprehensive retrieval of studies was carried out in scientific databases including PubMed, Web of Science, Elsevier, and CNKI. By using ("irritable bowel syndrome" OR "IBS") AND ("natural product" OR "natural compound" OR "phytochemical") as keywords, the eligible studies were screened, and the relevant information about therapeutic action and mechanism of natural products treating IBS was extracted.

RESULTS

Natural products against IBS consisted of four categories, namely, terpenoids, flavonoids, alkaloids, and phenols. Furthermore, the underlying mechanisms for natural products treating IBS were tightly associated with increased TJs and mucus protein expression, regulation of the brain-gut axis and gut microbiota structure, and inhibition of inflammatory response and intestinal mucosal damage.

CONCLUSION

Natural products could be extremely prospective candidate drugs used to treat IBS, and further preclinical and clinical researches are needed to guarantee their efficacy and safety.

5-HT7 receptor-dependent intestinal neurite outgrowth contributes to visceral hypersensitivity in irritable bowel syndrome

Irritable bowel syndrome (IBS) is characterized by visceral hypersensitivity (VH) associated with abnormal serotonin/5-hydroxytryptamine (5-HT) metabolism and neurotrophin-dependent mucosal neurite outgrowth. The underlying mechanisms of VH remain poorly understood. We investigated the role of 5-HT₇ receptor in mucosal innervation and intestinal hyperalgesia. A high density of mucosal nerve fibres stained for 5-HT₇ was observed in colonoscopic biopsy specimens from IBS patients compared with those from healthy controls. Staining of 5-HT₃ and 5-HT₄ receptors was observed mainly in colonic epithelia with comparable levels between IBS and controls. Visceromotor responses to colorectal distension were evaluated in two mouse models, one postinfectious with Giardia and subjected to water avoidance stress (GW) and the other postinflammatory with trinitrobenzene sulfonic acid-induced colitis (PT). Increased VH was associated with higher mucosal density of 5-HT₇-expressing nerve fibres and elevated neurotrophin and neurotrophin receptor levels in the GW and PT mice. The increased VH was inhibited by intraperitoneal injection of SB-269970 (a selective 5-HT₇ antagonist). Peroral multiple doses of CYY1005 (a novel 5-HT₇ ligand) decreased VH and reduced mucosal density of 5-HT₇-expressing nerve fibres in mouse colon. Human neuroblastoma SH-SY5Y cells incubated with bacteria-free mouse colonic supernatant, 5-HT, nerve growth factor, or brain-derived neurotrophic factor exhibited nerve fibre elongation, which was inhibited by 5-HT₇ antagonists. Gene silencing of HTR7 also reduced the nerve fibre length. Activation of 5-HT₇ upregulated NGF and BDNF gene expression, while stimulation with neurotrophins increased the levels of tryptophan hydroxylase 2 and 5-HT₇ in neurons. A positive-feedback loop was observed between serotonin and neurotrophin pathways via 5-HT₇ activation to aggravate fibre elongation, whereby 5-HT₃ and 5-HT₄ had no roles. In conclusion, 5-HT₇-dependent mucosal neurite outgrowth contributed to VH. A novel 5-HT₇ antagonist could be used as peroral analgesics for IBS-related pain.

Antidepressant prescription in acute myocardial infarction is associated with increased mortality 1 year after discharge

AIMS

To assess the impact of antidepressant (AD) prescription at discharge on 1-year outcome of patients presenting with acute myocardial infarction (AMI) in Switzerland.

METHODS

We used data from the AMIS Plus registry including patients admitted between March 2005 and August 2016 with AMI to a Swiss hospital who were followed up by telephone, 12 months after discharge. We compared patients who received AD medication at discharge with those who did not, with regard to baseline characteristics and outcomes in 1-year follow-ups using logistic regression. Outcome endpoints included mortality, re-hospitalisation, cerebrovascular events, re-infarction, percutaneous coronary intervention (PCI), coronary artery bypass graft as well as pacemaker and/or cardioverter-defibrillator implantations. Additionally, work and daily life conditions were compared between the groups.

RESULTS

Among 8911 AMI patients, 565 (6.3%) received AD at discharge. These patients were predominantly female, older, experienced more often non-ST-segment elevation myocardial infarction, were in higher Killip classes, and had more frequently hypertension, diabetes, dyslipidaemia, obesity and comorbidities. They underwent less frequently PCI, and stayed in hospital longer. The AD-receiving group had higher crude all-cause mortality at 1-year follow-up than the non-receiving group (7.4% vs 3.4%; p < .001) and AD prescription was an independent predictor for mortality (OR 1.67; CI: 1.17 to 2.40).

CONCLUSION

AD medication at discharge was associated with poorer prognosis in AMI patients at 1-year follow-up. However, this study has limited data on depression diagnosis and drug classes. Further research is needed to pinpoint the causes and underlying pathomechanisms for the higher mortality observed in this patient group.

Efficacy and safety of 5-hydroxytryptamine 3 receptor antagonists in irritable bowel syndrome: A systematic review and meta-analysis of randomized controlled trials

AIM

We assessed the efficacy and safety of 5-hydroxytryptamine (5-HT3) receptor antagonists in adults with non-constipated irritable bowel syndrome (IBS) or diarrhea-predominant IBS (IBS-D).

METHODS

We searched PubMed, MEDLINE, EMBASE, and the Cochrane Controlled Trials Register for randomized controlled trials (RCTs) involving adults with non-constipated IBS or IBS-D that compared 5-HT3 receptor antagonists with placebo or other conventional treatment. Dichotomous symptom data were pooled to obtain the relative risk (RR) and 95% confidence intervals (CIs) for improving global IBS symptoms, abdominal pain and abnormal bowel habits, or stool consistency symptoms after therapy, and adverse events, including constipation. Meta- analysis was performed with Mantel Haenszel method using Revman 5.3 software.

RESULTS

We included 21 RCTs; 16 were high quality (Jadad score ≥ 4). The pooled RR of global IBS symptoms improved by 5-HT3 receptor antagonists versus placebo or mebeverine was 1.56 (95% CI: 1.43-1.71); alosetron, ramosetron, and cilansetron had similar treatment effects. The pooled RR of abdominal pain relieved by 5-HT3 receptor antagonists versus placebo was 1.33 (95% CI: 1.26-1.39). The pooled RR showed that 5-HT3 receptor antagonists improved abnormal bowel habits or stool consistency symptoms (RR = 1.63, 95% CI: 1.33, 1.99). The pooled RR of adverse events following 5-HT3 receptor antagonist treatment was 1.15 (95% CI: 1.08, 1.22). Subgroup analysis indicated that alosetron had a high rate of adverse effects (RR = 1.16, 95% CI: 1.08, 1.25); adverse events following ramosetron treatment were not statistically significantly different. 5-HT3 receptor antagonists were likelier to cause constipation: the pooled RR of constipation developing with 5-HT3 receptor antagonist versus placebo was 3.71 (95% CI: 2.98-4.61). However, constipation was likelier in patients with non-constipated IBS after taking 5-HT3 receptor antagonists than in patients with IBS-D only (non-constipated IBS and IBS-D: RR = 5.28 [95% CI: 3.93, 7.08] vs. IBS-D only 3.24 [2.54, 4.12]).

CONCLUSIONS

Ramosetron, cilansetron, ondansetron, and alosetron are effective for treating non-constipated IBS and IBS-D. Our systematic review found rare serious adverse events.

Common Functional Gastroenterological Disorders Associated With Abdominal Pain

Although abdominal pain is a symptom of several structural gastrointestinal disorders (eg, peptic ulcer disease), this comprehensive review will focus on the 4 most common nonstructural, or functional, disorders associated with abdominal pain: functional dyspepsia, constipation-predominant and diarrhea-predominant irritable bowel syndrome, and functional abdominal pain syndrome. Together, these conditions affect approximately 1 in 4 people in the United States. They are associated with comorbid conditions (eg, fibromyalgia and depression), impaired quality of life, and increased health care utilization. Symptoms are explained by disordered gastrointestinal motility and sensation, which are implicated in various peripheral (eg, postinfectious inflammation and luminal irritants) and/or central (eg, stress and anxiety) factors. These disorders are defined and can generally be diagnosed by symptoms alone. Often prompted by alarm features, selected testing is useful to exclude structural disease. Identifying the specific diagnosis (eg, differentiating between functional abdominal pain and irritable bowel syndrome) and establishing an effective patient-physician relationship are the cornerstones of therapy. Many patients with mild symptoms can be effectively managed with limited tests, sensible dietary modifications, and over-the-counter medications tailored to symptoms. If these measures are not sufficient, pharmacotherapy should be considered for bowel symptoms (constipation or diarrhea) and/or abdominal pain; opioids should not be used. Behavioral and psychological approaches (eg, cognitive behavioral therapy) can be helpful, particularly in patients with chronic abdominal pain who require a multidisciplinary pain management program without opioids.

Effect of TongXie-YaoFang on Cl(-) and HCO3 (-) Transport in Diarrhea-Predominant Irritable Bowel Syndrome Rats

TongXie-YaoFang (TXYF) can effectively alleviate the symptoms of diarrhea-predominant irritable bowel syndrome (D-IBS) patients. However, the curative mechanism has not been fully clarified. The study was designed to investigate the effect of TXYF on the colonic ion transport induced by serotonin (5-HT) in D-IBS rats. A method of multiple stress (neonatal maternal separation (NMS) combined with restraint stress (RS)) was used to induce the D-IBS model. The model rats were randomly divided into two groups: NMS + RS group and TXYF-formula group, and the normal control (no handling) rats were classified as NH group. In the NMS + RS group, the change of short-circuit current (ΔI sc) induced by 5-HT was lower than that in the NH and TXYF-formula groups. After removing of the extracellular Cl(-) or HCO3 (-) or basolateral Na(+) or blocking the cystic fibrosis transmembrane conductance regulator (CFTR), Na(+)-K(+)-2Cl(-) cotransporter (NKCC), Na(+)-HCO3 (-) cotransporter, Cl(-)/HCO3 (-) exchanger, K(+) channel, or Na(+)/K(+)-ATPase, respectively, there was no difference in 5-HT-induced ΔI sc among the three groups. These data suggest that TXYF can regulate 5-HT-induced Cl(-) and HCO3 (-) secretion, possibly mediated by the combined action of CFTR, NKCC, Na(+)-HCO3 (-) cotransporter, Cl(-)/HCO3 (-) exchanger, K(+) channel, and Na(+)/K(+)-ATPase.