Metabolic and toxicological considerations for the latest drugs used to treat irritable bowel syndrome

Characterization of disulfide bridges containing cyclic peptide Linaclotide and its degradation products by using LC-HRMS/MS

Linaclotide (LINA) is a first-in-class guanylate cyclase agonist used for treating irritable bowel syndrome with constipation (IBS-C) and chronic idiopathic constipation. Stress degradation studies were performed to examine LINA's intrinsic stability, adhering to International Council for Harmonisation of Technical ICH) guidelines Q1A (R2). The current study endeavours to elucidate the stability behavior of LINA by exposing various stress conditions. A simple LC method was developed for effective separation of all LINA degradation products using a Waters Symmetry C18 column (150 ×4.6 mm, 3.5 µm) as the stationary phase. The generated degradation products were identified and characterized by using high-resolution mass spectrometry (LC-HRMS), MS/MS studies. The mechanistic fragmentation pathway for the seven degradation products was established and the chemical structure for the identified degradation products was elucidated. LINA was susceptible to degrade under acidic, basic, neutral, photolytic, and oxidative conditions. A total of three Pseudo DPs, DP-1, DP-2, and DP-3, were formed under acidic conditions while using methanol as the co-solvent. Additionally, degradation products (DPs) were identified: DP-4 formed under basic stress condition and DP-5 under neutral, thermal, and photolytic conditions. Furthermore, DP-6 and DP-7 were formed under oxidative stress condition. This study established the mechanistic fragmentation pathways and elucidated the chemical structures of the degradation products, offering valuable insights for generics and novel formulation drug development.

Pharmacokinetic considerations for drugs that treat diarrhea-predominant irritable bowel syndrome: what's new?

INTRODUCTION

Irritable bowel syndrome (IBS), which presents a significant healthcare and socioeconomic burden, is one of the main issues in the field of therapy. Hence, it is imperative to tackle this matter by evaluating the safety and efficacy of the available treatments and determining the ideal approach for each patient.

AREAS COVERED

We reviewed the pharmacokinetics and safety of pharmacologic interventions administered in diarrhea-predominant IBS (IBS-D) patients. PubMed, Google Scholar and the USFDA databases were searched up to November 2023 to include all updated information on eluxadoline, alosetron, and rifaximin.

EXPERT OPINION

The most effective way to treat IBS-D is to focus on managing the most common symptoms. However, healthcare providers face a challenge when it comes to identifying the right treatment for each patient, and the root cause of this is the diversity of IBS-D population. Studies have shown that there are differences in how men and women metabolize drugs, which may lead to gender-specific adverse reactions. Women tend to have higher drug concentrations in their bloodstream and take longer to eliminate them. Therefore, healthcare providers may need to reduce the dosage for female patients. Integrating IBS care into sustainable development efforts can indirectly contribute to achieving SDGs and promote health and well-being for all.

Pharmacological treatments for patients with irritable bowel syndrome: An umbrella review of systematic reviews and meta-analyses

INTRODUCTION

Several pharmacological treatments are beneficial for patients with irritable bowel syndrome (IBS), and there are numbers of systematic reviews evaluating the effectiveness of these treatments. However, the overall quality of the evidence has not been quantitatively assessed. The aim of this study is to evaluate the possible biases in the published systematic reviews and determine the treatments with reliable evidence.

METHODS AND ANALYSIS

We will perform an umbrella review to identify eligible systematic reviews. A comprehensive literature search will be conducted in MEDLINE, EMBASE, and the Cochrane library for systematic reviews. We will describe the general information such as participants, interventions, outcome measurements, and conclusion. Additionally, the heterogeneity and inconsistency between trials will be assessed by the I statistical test and Cochrane Q test. We will assess risk of bias, and summarize the strength evidence.

CONCLUSION

The umbrella reviews will assess the reliability of the evidence so that doctors and patients can make better medical choices.

PROSPERO REGISTRATION NUMBER

CRD42018109597.

Melatonin's role as a co-adjuvant treatment in colonic diseases: A review

Melatonin is produced in the pineal gland as well as many other organs, including the enterochromaffin cells of the digestive mucosa. Melatonin is a powerful antioxidant that resists oxidative stress due to its capacity to directly scavenge reactive species, to modulate the antioxidant defense system by increasing the activities of antioxidant enzymes, and to stimulate the innate immune response through its direct and indirect actions. In addition, the dysregulation of the circadian system is observed to be related with alterations in colonic motility and cell disruptions due to the modifications of clock genes expression. In the gastrointestinal tract, the activities of melatonin are mediated by melatonin receptors (MT2), serotonin (5-HT), and cholecystokinin B (CCK2) receptors and via receptor-independent processes. The levels of melatonin in the gastrointestinal tract exceed by 10-100 times the blood concentrations. Also, there is an estimated 400 times more melatonin in the gut than in the pineal gland. Gut melatonin secretion is suggested to be influenced by the food intake. Low dose melatonin treatment accelerates intestinal transit time whereas high doses may decrease gut motility. Melatonin has been studied as a co-adjuvant treatment in several gastrointestinal diseases including irritable bowel syndrome (IBS), constipation-predominant IBS (IBS-C), diarrhea-predominant IBS (IBS-D), Crohn's disease, ulcerative colitis, and necrotizing enterocolitis. The purpose of this review is to provide information regarding the potential benefits of melatonin as a co-adjuvant treatment in gastrointestinal diseases, especially IBS, Crohn's disease, ulcerative colitis, and necrotizing enterocolitis.

Polyunsaturated Fatty Acids and Their Derivatives: Therapeutic Value for Inflammatory, Functional Gastrointestinal Disorders, and Colorectal Cancer

Polyunsaturated fatty acids (PUFAs) are bioactive lipids which modulate inflammation and immunity. They gained recognition in nutritional therapy and are recommended dietary supplements. There is a growing body of evidence suggesting the usefulness of PUFAs in active therapy of various gastrointestinal (GI) diseases. In this review we briefly cover the systematics of PUFAs and their metabolites, and elaborate on their possible use in inflammatory bowel disease (IBD), functional gastrointestinal disorders (FGIDs) with focus on irritable bowel syndrome (IBS), and colorectal cancer (CRC). Each section describes the latest findings from in vitro and in vivo studies, with reports of clinical interventions when available.

Alcohol Use Disorder Increases the Risk of Irritable Bowel Disease: A Nationwide Retrospective Cohort Study

Alcohol use disorder (AUD) is considered a possible risk factor for irritable bowel syndrome (IBS); however, previous studies investigating the association between AUD and IBS have yielded inconsistent results. The study investigated whether AUD increases the risk of IBS by using a population-based database in Taiwan.This retrospective matched-cohort study included the health insurance claims data of 56,355 AUD inpatients and 225,420 randomly selected controls by frequency-matched for sex, age, and index year. Cox proportional hazards regression analysis was performed to measure the risk of IBS among AUD patients compared with non-AUD patients.During the follow-up period, the incidence rate ratio (IRR) of IBS had 12.3-fold (95% CI: 11.9-12.7) in the AUD patients than non-AUD patients and the adjusted hazard ratio (aHR) for IBS in the AUD patients was 5.51 (95% CI: 4.36-6.96). For several comorbidities, the risk of IBS was significantly higher in the AUD patients than in non-AUD patients, with aHRs of 2.14 (95% confidence interval [CI]: 1.19-3.84), 2.05 (95% CI: 1.06-3.96), and 2.91 (95% CI: 1.26-6.72) for sleep disorders, acute pancreatitis, and hepatitis B, respectively. When we stratified the severity of AUD according to the length of hospital stay, the aHRs exhibited a significant correlation (P < 0.001) with severity, yielding aHRs of 3.24 (95% CI: 2.49-4.22), 11.9 (95% CI: 8.96-15.9), and 26.1 (95% CI: 19.4-35.2) for mild, moderate, and severe AUD, respectively.The risk of IBS was higher among AUD patients, and increased with the length of hospital stay.

Effectiveness of probiotics in irritable bowel syndrome: Updated systematic review with meta-analysis

AIM: To investigate the efficacy of probiotics in irritable bowel syndrome (IBS) patients.

METHODS: PubMed, Cochrane library, Scopus, Google Scholar, and Clinicaltrial.gov databases were searched for literature published between September 2007 and December 2013. The applied Mesh terms were “probiotics,”“irritable bowel syndrome,” and “irritable bowel syndrome treatment.” The collected data contained24 clinical trials, of which 15 were eligible for meta-analysis and nine were reviewed systematically. All studies were randomized placebo-controlled trials in patients with IBS that investigated the efficacy of probiotics in IBS improvement. The Jadad score was used to assess the methodological quality of trials. The quality scale ranges from 0 to 5 points, with a score ≤ 2 indicating a low quality report, and a score of ≥ 3 indicating a high quality report. Relative risk (RR), standardized effect size, and 95%CI were calculated using the DerSimonian-Laird method. The Cochran Q test was used to test heterogeneity with P < 0.05. Funnel plots were constructed and Egger’s and Begg-Mazumdar tests were performed to assess publication bias.

RESULTS: A total of 1793 patients were included in the meta-analysis. The RR of responders to therapies based on abdominal pain score in IBS patients for two included trials comparing probiotics to placebo was 1.96 (95%CI: 1.14-3.36; P = 0.01). RR of responders to therapies based on a global symptom score in IBS patients for two included trials comparing probiotics with placebo was 2.43 (95%CI: 1.13-5.21; P = 0.02). For adequate improvement of general symptoms in IBS patients, the RR of seven included trials (six studies) comparing probiotics with placebo was 2.14 (95%CI: 1.08-4.26; P = 0.03). Distension, bloating, and flatulence were evaluated using an IBS severity scoring system in three trials (two studies) to compare the effect of probiotic therapy in IBS patients with placebo, the standardized effect size of mean differences for probiotics therapy was -2.57 (95%CI: -13.05--7.92).

CONCLUSION: Probiotics reduce pain and symptom severity scores. The results demonstrate the beneficial effects of probiotics in IBS patients in comparison with placebo.

Stress-induced visceral pain: toward animal models of irritable-bowel syndrome and associated comorbidities

Visceral pain is a global term used to describe pain originating from the internal organs, which is distinct from somatic pain. It is a hallmark of functional gastrointestinal disorders such as irritable-bowel syndrome (IBS). Currently, the treatment strategies targeting visceral pain are unsatisfactory, with development of novel therapeutics hindered by a lack of detailed knowledge of the underlying mechanisms. Stress has long been implicated in the pathophysiology of visceral pain in both preclinical and clinical studies. Here, we discuss the complex etiology of visceral pain reviewing our current understanding in the context of the role of stress, gender, gut microbiota alterations, and immune functioning. Furthermore, we review the role of glutamate, GABA, and epigenetic mechanisms as possible therapeutic strategies for the treatment of visceral pain for which there is an unmet medical need. Moreover, we discuss the most widely described rodent models used to model visceral pain in the preclinical setting. The theory behind, and application of, animal models is key for both the understanding of underlying mechanisms and design of future therapeutic interventions. Taken together, it is apparent that stress-induced visceral pain and its psychiatric comorbidities, as typified by IBS, has a multifaceted etiology. Moreover, treatment strategies still lag far behind when compared to other pain modalities. The development of novel, effective, and specific therapeutics for the treatment of visceral pain has never been more pertinent.

The safety of novel drugs used to treat irritable bowel syndrome

INTRODUCTION

Irritable bowel syndrome (IBS) is a chronic gastrointestinal (GI) disorder with a high prevalence. Besides efficacy, the safety of each drugs used to treat GI disorders is an important issue in the drug development process.

AREAS COVERED

This article reviews all Phase I to IV clinical trials or case reports with results related to the safety of novel GI drugs. The drugs are currently approved or under evaluation for approval.

EXPERT OPINION

Most of the reported adverse events were related to the GI tract with mild-to-moderate severity. Diarrhea was significantly higher versus placebo following use of linaclotide and renzapride, similar to that of constipation with ramosetron. Lubiprostone, linaclotide and rifaximin with low systemic bioavailability have less adverse events and exert more advantageous results. Asimadoline acts peripherally on κ-opioid receptors and is not associated with CNS side effects. As lubiprostone and linaclotide cause dose-dependent adverse events, starting the treatment with the lowest effective doses is advised. Ramosetron is under evaluation for diarrhea-predominant IBS due to its acceptable safety and tolerability, besides its efficacy. Rifaximin, asimadoline and renzapride are still in need of more long-term studies regarding their safety.

Efficacy and tolerability of renzapride in irritable bowel syndrome: a meta-analysis of randomized, controlled clinical trials including 2528 patients

INTRODUCTION

By targeting different subtypes of 5-hydroxytryptamine (5HT) receptors in the gastrointestinal (GI) tract, several drugs have been introduced for the management of irritable bowel syndrome (IBS). Renzapride is a full agonist for 5HT4 receptor and an antagonist to 5HT2b and 5HT3 receptors which is thought a promising therapeutic agent for constipation predominant IBS (C-IBS) patients due to its accelerating effect on the GI tract. In this meta-analysis, our aim was to evaluate the efficacy and tolerability of renzapride in the management of IBS.

MATERIAL AND METHODS

A search was done from 1992 to February 2013 for placebo-controlled trials that investigated the efficacy of renzapride in IBS.

RESULTS

Relative risk (RR) for clinical efficacy in IBS patients treated for 5 weeks or less comparing renzapride to placebo was 1.07 (95% CI = 0.89-1.29, p = 0.38). This value for IBS patients treated for more than 5 weeks was 1.04 (95% CI = 0.78-1.239, p = 0.77). The RR for clinical efficacy in IBS patients treated with renzapride (4 mg) for 5 weeks or less and more than 5 weeks in comparison to placebo was 1.2 (95% CI = 0.97-1.48, p = 0.1) and 1.16 (95% CI = 0.98-1.37, p = 0.08), respectively, which were statistically non-significant but clinically important. The analysis of tolerability demonstrated that amongst different reported adverse effects, renzapride caused diarrhea more than placebo (RR = 1.61 with a 95% CI = 1.16-2.24, p = 0.004). The RR for withdrawals from renzapride compared to placebo was 1.58 (95% CI = 1.26-2.07, p = 0.0007).

CONCLUSIONS

Renzapride is not superior to placebo in relieving IBS symptoms and causes significant incidences of diarrhea and drop-outs due to adverse effects in treated patients vs. placebo. Thus, this medicine might be a cost burden to patients without providing good effectiveness.

Lubiprostone: pharmacokinetic, pharmacodynamic, safety and regulatory aspects in the treatment of constipation-predominant irritable bowel syndrome

INTRODUCTION

Lubiprostone acts locally (apical membrane of human intestinal epithelial cells) as a highly selective type-2 chloride channel activator. It was approved in the USA for chronic idiopathic constipation (January 2006) and in women aged ≥ 18 years suffering from irritable bowel syndrome with constipation (IBS-C) (April 2008). So far, the only other pro-secretory medication approved in IBS-C and currently available in USA and Europe (since August and November 2012, respectively) is linaclotide.

AREAS COVERED

This review outlines the regulatory history, pharmacokinetic, pharmacodynamic and safety data in the treatment of IBS-C with a European perspective. It is based on publicly available data, namely, published literature, drug labels and the FDA's spontaneous reporting system.

EXPERT OPINION

Although interesting pharmacodynamic data suggest that lubiprostone may have additional mechanisms of action, its beneficial effects in IBS-C must be confirmed in the actual clinical scenario taking into account the new version of European Medicines Agency's guideline. This is especially important with regard to duration of studies (recommended to be at least 6 months) to adequately assess long-term sustained efficacy, withdrawal, rebound and safety. Further research is warranted in uncertain areas (i.e., males, pediatric and elderly patients). On the basis of current data, it is still too early to draw definite conclusions on the overall risk-benefit balance for IBS-C.