Current developments in pharmacological therapeutics for chronic constipation

A real-world study of persistence and adherence to prescription medications in patients with chronic idiopathic constipation in the United States

BACKGROUND

At present, 4 prescription therapies have been approved by the US Food and Drug Administration for the treatment of chronic idiopathic constipation (CIC) in adults.

OBJECTIVES

To compare persistence with and adherence to prucalopride vs 3 other prescription medications for CIC in a US population.

METHODS

This retrospective, observational cohort study used data from the IBM MarketScan Commercial Claims and Encounters and Medicare Supplemental Databases (January 2015-June 2020). Inclusion criteria were patients (aged ≥18 years) with at least 1 prescription fill for prucalopride, lubiprostone, linaclotide, or plecanatide on or after April 2, 2019 (commercial availability of prucalopride), and at least 1 constipation-related diagnosis code. Persistence was assessed by time to discontinuation, and adherence was assessed by the proportion of days covered (PDC) and the proportion of patients who achieved PDC of at least 80%. Adjusted hazard ratios (HRs) for discontinuation and odds ratios for adherence were calculated.

RESULTS

A total of 14,700 patients (mean age = 48.3 years; female = 81.9%) were included (prucalopride, n = 675; lubiprostone, n = 1,591; linaclotide, n = 11,105; plecanatide, n = 1,329). After adjusting for confounding factors, the HRs for discontinuation were significantly higher for all comparator medications compared with prucalopride after 2 months (HR [95% CI]: lubiprostone, 1.70 [1.48-1.95]; linaclotide, 1.25 [1.10-1.41]; plecanatide, 1.31 [1.13-1.51], all P < 0.001). The unadjusted mean (SD) PDC was 0.53 (0.32) with prucalopride compared with 0.41 (0.31); P less than 0.001 with lubiprostone, 0.48 (0.31), P less than 0.05 with linaclotide, and 0.48 (0.29), P = 0.98 with plecanatide. The comparator medications were all associated with lower odds of achieving PDC of at least 80% relative to prucalopride (odds ratio [95% CI]: lubiprostone, 0.52 [0.40-0.69], P < 0.001; linaclotide, 0.73 [0.58-0.93], P = 0.009; plecanatide, 0.70 [0.53-0.93], P = 0.015).

CONCLUSIONS

The findings of this study indicate that prucalopride has higher treatment persistence and adherence compared with other CIC prescription medications. This research represents the first instance of a real-world claims study showcasing such outcomes.

Analysis of differentially expressed lncRNAs and mRNAs associated with slow‑transit constipation

Slow transit constipation (STC) is a refractory gastrointestinal disease, accounting for approximately 13 ∼ 37 % of chronic constipation. However, the molecular mechanism of STC remains poorly understood. Herein, this study aims to identify the key mRNAs and lncRNAs associated with STC. To this end, we performed high-throughput RNA sequencing to identify differentially expressed (DE) mRNAs and lncRNAs in the whole-layer sigmoid intestinal tissues from 4 STC patients and 4 non-STC patients. The identified DE lncRNAs and mRNAs were validated through quantitative real-time PCR. Weighted gene co-expression network analysis (WGCNA) and Pearson correlation analysis were conducted to determine the significantly correlated DE mRNA-lncRNA pairs. A total of 1420 DE lncRNAs and 1634 DE mRNAs were identified. Kyoto Encyclopedia of Genes and Genomes analysis of DE mRNAs indicated that these DE mRNAs might be associated with systemic lupus erythematosus, alcoholism, intestinal immune network for IgA production, inflammatory bowel disease, NF-kappa B signaling pathway. WGCNA and Pearson correlation analyses jointly identified 16,577 significantly correlated DE mRNA-lncRNA pairs. Furthermore, lncRNAs LINC00641, LINC02268, LINC03013 were identified as hub lncRNAs. The protein-protein interaction (PPI) network of proteins encoded by DE mRNAs was established, and PPI-based analysis revealed that Interleukin 2(IL2), CD80 molecule (CD80), interleukin-17A (IL-17A) might play significant roles in the development of STC. This study analyzes the expression profiles of lncRNAs and mRNAs associated with STC. Our findings will contribute to further understanding of the molecular mechanism of STC and provide potential diagnostic or therapeutic biomarkers for STC.

Effects of natural products on functional constipation: analysis of active ingredient and mechanism

Constipation is a prevalent clinical ailment of the gastrointestinal system, yet its pathogenesis remains ambiguous. Despite the availability of numerous treatment modalities, they are insufficient in resolving the issue for patients. This work conducted a comprehensive review of the existing literature pertaining to the utilization of natural products for the treatment of constipation, with a focus on the efficacy of natural products in treating constipation, and to provide a comprehensive summary of their underlying mechanisms of action. Upon conducting a thorough review of the extant literature, we found that natural products can effectively treat constipation as modern synthetic drugs and compounded drugs with acetylcholinesterase (AChE) effects, rich in fiber and mucus, and the effects of increasing the tension of the ileum and gastrointestinal tract muscle, mediating signaling pathways, cytokine, excitability of the smooth muscle of the gastrointestinal tract, and regulating the homeostasis of intestinal flora. However, there is a wide variety of natural products, and there are still relatively few studies; the composition of natural products is complex, and the mechanism of action of natural products cannot be clarified. In the future, we need to further improve the detailed mechanism of natural products for the treatment of constipation.

Total alditols from Cistanche deserticola attenuate functional constipation by regulating bile acid metabolism

HEADINGS ETHNOPHARMACOLOGICAL RELEVANCE

Functional constipation (FC), characterized by chronic constipation, significantly impacts physiological function and induces psychological stress in patients. However, current clinical treatment options for FC are currently limited. Cistanche deserticola, a traditional Chinese medicine that promotes intestinal moisture and bowel relaxation, contains cistanche total alditol extract (CTAE) as its primary active extract. However, the production of CTAE, its overall efficacy, and potential mechanisms for treating FC have yet to been investigated.

AIM OF THE STUDY

This study aimed to reveal the overall efficacy and potential mechanism of action of CTAE in rats with FC using a combination of stable preparation, pharmacodynamics, non-targeted metabolomics, bile acid metabolomics, and western blotting.

MATERIALS AND METHODS

Fourteen batches of CTAE underwent quality testing. A rat model of FC was developed using diphenoxylate tablets. The comprehensive pharmacodynamic effects of CTAE on FC were evaluated using fecal characteristics (wet weight, dry weight, and water content), intestinal transmission (colonic EMG amplitude, colonic EMG frequency, propulsion length, and propulsion rate), serum and colon biochemical indicators, distribution of interstitial cells of Cajal (ICC), and pathological examination. Non-targeted metabolomics was performed to assess the changes in endogenous metabolite profiles induced by CTAE. Bile acid metabolomics and western blotting analyses were employed to validate the potential mechanisms of action of CTAE.

RESULTS

CTAE, with a total content of betaine, mannitol, D-fructose, glucose, and sucrose of (75.67 ± 3.73) %, significantly enhanced intestinal transit, regulated neurotransmitters, increased the expression of c-kit in ICC, and alleviated intestinal inflammation in rats with FC. Non-targeted metabolomics revealed that CTAE significantly alleviated FC-induced metabolic disorders, mainly the biosynthesis of primary bile acids. Targeted metabolomic analysis confirmed that CTAE regulated FC-induced bile acid disorders. Western-blotting results confirmed that CTAE increased the expression of CYP8B1, FGF15, TGR5, and FXR, thereby modulating bile acid synthesis and enterohepatic circulation.

CONCLUSION

CTAE demonstrates significant therapeutic effects on FC, primarily through the regulation of bile acid synthesis and enterohepatic circulation. These findings provide a promising foundation for the development and clinical application of novel CATE-based drugs.

Stool-softening effect and action mechanism of free anthraquinones extracted from Rheum palmatum L. on water deficit-induced constipation in rats

ETHNOPHARMACOLOGICAL RELEVANCE

In traditional Chinese herbal medicine, rhubarb is said to remove accumulation with purgation, clearing heat, and discharging fire. Modern pharmacology has shown that rhubarb extract has a purgative effect when given to experimental animals in an appropriate dose. However, the active components and their mechanism of action are still not clearly defined.

AIM OF THE STUDY

The current research aimed to evaluate the synergistic stool-softening effects and explore the action mechanism of rhubarb free anthraquinones (RhA) and their monomers on constipation in rats.

MATERIALS AND METHODS

A rat model of water deficit-induced constipation was established to induce constipation, and these rats were treated with RhA and its monomers. ELISA, histopathology, immunohistochemistry, qPCR and Western blotting based on network pharmacology and molecular docking were conducted to explore the possible mechanism of action of RhA and its monomers.

RESULTS

RhA, aloe-emodin, rhein, and chrysophanol showed stool-softening activity, and the combination of aloe-emodin and rhein had the strongest softening effect on faecal pellets. Aloe-emodin, rhein, and chrysophanol significantly increased the serum levels of vasoactive intestinal peptide (VIP), motilin (MTL), and substance P (SP), upregulated the expression of VIP, cyclase-associated protein 1 (CAP1), protein kinase A (PKA), cystic fibrosis transmembrane conductance regulator (CFTR), aquaporin 3 (AQP3), aquaporin 4 (AQP4), and aquaporin 8 (AQP8), decreased the expression of epithelial sodium channel (ENaC) and Na+/H+ exchanger 3 (NHE3), and reduced the colonic tissue concentration of Na+-K+-ATPase in the constipated rats. Osmolality of colonic fluid in model rats treated by RhA, aloe-emodin, rhein, and chrysophanol was increased.

CONCLUSION

Aloe-emodin, rhein, and chrysophanol were the stool-softening components of the RhA extract, and there were certain drug-interactions between the components. RhA upregulated VIP expression, activated the cyclic adenosine monophosphate protein kinase A (cAMP/PKA) pathway, and further stimulated CFTR expression while inhibiting NHE3 and ENaC expression, resulting in a hypertonic state in the colonic lumen. Water transport could then be driven by an osmotic gradient, which in turn led to the upregulation of AQP3, AQP4, and AQP8 expression. In addition, RhA likely improved gastrointestinal motility by increasing serum VIP, SP, and MTL concentrations, thus promoting faecal excretion.

Treatment of Chronic Constipation using Elobixibat in a Real-World Setting: A Retrospective Cohort Study using an Electronic Medical Records Database in Japan

Background

Chronic constipation is a common condition affecting people of all ages; therefore, the socioeconomic burden of chronic constipation is nonnegligible. Elobixibat (ELO), an ileal bail acid transport inhibitor, was launched in Japan in 2018. However, evidence of its use in diverse populations is limited.

Objectives

This study aimed to evaluate the prescription of ELO, risk factors associated with ELO discontinuation, and the continuation of stimulants or saline laxatives during ELO treatment in a real-world setting using an extensive electronic medical records database that primarily includes data from acute-care hospitals.

Methods

Data of patients prescribed for ELO from April 1, 2018, to March 31, 2022, were extracted from the database. The discontinuation of ELO and stimulant or saline laxatives during ELO treatment was evaluated using the Kaplan-Meier method. The Cox proportional hazards model evaluated risk factors associated with laxative discontinuation.

Results

In total, 11,062 patients were evaluated. The rate of ELO discontinuation within 360 days of initiation was 78.7%. Hospitalized at the ELO initiation, stage 5 chronic kidney disease, and diagnosis of constipation by departments of obstetrics and gynecology or by departments of malignant neoplasm were identified as risk factors for discontinuation. Diagnosis of constipation, diabetes mellitus, Parkinson's disease, and previous laxative treatment was associated with a lower risk of ELO discontinuation. The prescription rate of stimulants and saline laxatives markedly decreased after ELO initiation; furthermore, nearly half of patients who were continuously prescribed ELO discontinued these laxatives within 360 days.

Conclusions

The discontinuation of ELO was associated with various factors and using ELO may be beneficial in the withdrawal of concurrent stimulants and saline laxatives. These findings may help effectively manage chronic constipation.

Rifaximin Ameliorates Loperamide-Induced Constipation in Rats through the Regulation of Gut Microbiota and Serum Metabolites

Structural changes in the gut microbiota are closely related to the development of functional constipation, and regulating the gut microbiota can improve constipation. Rifaximin is a poorly absorbed antibiotic beneficial for regulating gut microbiota, but few studies have reported its effects on constipation. The purpose of this study was to investigate the effect of rifaximin on loperamide-induced constipation in SD rats. The results showed that rifaximin improved constipation by increasing serum 5-HT, SP, and the mRNA expression of AQP3, AQP8, and reducing the mRNA expression of TLR2 and TLR4. In addition, rifaximin could regulate the gut microbiota of constipated rats, such as increasing the potentially beneficial bacteria Akkermansia muciniphila and Lactobacillus murinus, reducing the Bifidobacterium pseudolongum. According to metabolomics analysis, many serum metabolites, including bile acids and steroids, were changed in constipated rats and were recovered via rifaximin intervention. In conclusion, rifaximin might improve loperamide-induced constipation in rats by increasing serum excitatory neurotransmitters and neuropeptides, modulating water metabolism, and facilitating intestinal inflammation. Muti-Omics analysis results showed that rifaximin has beneficial regulatory effects on the gut microbiota and serum metabolites in constipated rats, which might play critical roles in alleviating constipation. This study suggests that rifaximin might be a potential strategy for treating constipation.

The postbiotic of hawthorn-probiotic ameliorating constipation caused by loperamide in elderly mice by regulating intestinal microecology

Background

Constipation is common gastrointestinal disorder with high prevalence and recurrence, making people suffering. However, the treatment for constipation remains ineffectual. We aimed to the study the effects and mechanisms of postbiotic of hawthorn-probiotic on loperamide modeled old KM mice.

Methods

Constipated mice were grouped and treated with 10% lactulose (Y), hawthorn group (S), probiotic group (F) and postbiotic of hawthorn-probiotic (FS). Fecal changes were observed. AQP3 and Enac-γ were measured by RT-qPCR and Western blotting, intestinal barrier by H&E and immunofluorescence staining, cell proliferation and apoptosis by CCK8 and flow cytometry. Gut microbiota was further determined by 16 s rRNA sequence of feces.

Results

Postbiotic of hawthorn-probiotic improved intestinal movement and pathomorphology, elevated AQP3, Enac-γ and mucin-2 expression, accompanied by decreased serum TNF-α and cell apoptosis, but increased proliferation. Furthermore, it modified the gut microbiota of constipated mice, featured by upregulation of Lactobacillaceae.

Conclusion

Postbiotic of hawthorn-probiotic relieved constipation by combined effects of regulating intestinal water and sodium metabolism, maintain intestinal barrier and gut microflora.Graphical Abstract.

Engineered 5-HT producing gut probiotic improves gastrointestinal motility and behavior disorder

Slow transit constipation is an intractable constipation with unknown aetiology and uncertain pathogenesis. The gut microbiota maintains a symbiotic relationship with the host and has an impact on host metabolism. Previous studies have reported that some gut microbes have the ability to produce 5-hydroxytryptamine (5-HT), an important neurotransmitter. However, there are scarce data exploiting the effects of gut microbiota-derived 5-HT in constipation-related disease. We genetically engineered the probiotic Escherichia coli Nissle 1917 (EcN-5-HT) for synthesizing 5-HT in situ. The ability of EcN-5-HT to secrete 5-HT in vitro and in vivo was confirmed. Then, we examined the effects of EcN-5-HT on intestinal motility in a loperamide-induced constipation mouse model. After two weeks of EcN-5-HT oral gavage, the constipation-related symptoms were relieved and gastrointestinal motility were enhanced. Meanwhile, administration of EcN-5-HT alleviated the constipation related depressive-like behaviors. We also observed improved microbiota composition during EcN-5-HT treatment. This work suggests that gut microbiota-derived 5-HT might promise a potential therapeutic strategy for constipation and related behavioral disorders.

Abnormal bile acid metabolism is an important feature of gut microbiota and fecal metabolites in patients with slow transit constipation

Destructions in the intestinal ecosystem are implicated with changes in slow transit constipation (STC), which is a kind of intractable constipation characterized by colonic motility disorder. In order to deepen the understanding of the structure of the STC gut microbiota and the relationship between the gut microbiota and fecal metabolites, we first used 16S rRNA amplicon sequencing to evaluate the gut microbiota in 30 STC patients and 30 healthy subjects. The α-diversity of the STC group was changed to a certain degree, and the β-diversity was significantly different, which indicated that the composition of the gut microbiota of STC patients was inconsistent with healthy subjects. Among them, Bacteroides, Parabacteroides, Desulfovibrionaceae, and Ruminiclostridium were significantly upregulated, while Subdoligranulum was significantly downregulated. The metabolomics showed that different metabolites between the STC and the control group were involved in the process of bile acids and lipid metabolism, including taurocholate, taurochenodeoxycholate, taurine, deoxycholic acid, cyclohexylsulfamate, cholic acid, chenodeoxycholate, arachidonic acid, and 4-pyridoxic acid. We found that the colon histomorphology of STC patients was significantly disrupted, and TGR5 and FXR were significantly downregulated. The differences in metabolites were related to changes in the abundance of specific bacteria and patients’ intestinal dysfunction. Analysis of the fecal genomics and metabolomics enabled separation of the STC from controls based on random forest model prediction [STC vs. control (14 gut microbiota and metabolite biomarkers)—Sensitivity: 1, Specificity: 0.877]. This study provided a perspective for the diagnosis and intervention of STC related with abnormal bile acid metabolism.

Pharmacokinetics of DA-6886, A New 5-HT4 Receptor Agonist, in Rats

DA-6886 is a novel serotonin (5-hydroxytrypamine [5-HT]) receptor 4 agonist for the potential treatment of constipation-predominant irritable bowel syndrome. The purpose of this study was to validate the quantitative assay of DA-6886 in rat plasma and to evaluate the pharmacokinetics and tissue distribution of DA-6886 in rats. The liquid chromatography–tandem mass spectrometry (LC–MS/MS) method for the robust quantification of DA-6886 in rat plasma was successfully validated and applied to the pharmacokinetic studies in rats. The pharmacokinetic parameters of DA-6886 in rats were evaluated following single intravenous or oral administration at three dose levels (2, 10, and 20 mg/kg). DA-6886 exhibited a smaller dose-normalized area under the plasma concentration–time curve (AUC) values and faster clearances in the low-dose group than in the high-dose group following both intravenous and oral administration. The steady-state volume of distribution (V_ss) of DA-6886 was relatively large (4.91–7.84 L/kg), which was consistent with its high distribution to the liver, kidney, lung, and digestive tract, and was dose-independent. After oral administration, the extent of absolute bioavailability (F) tended to increase (18.9–55.0%) with an increasing dose. The slope of the log-transformed AUC and/or C_max values versus log dose was greater than unity and greater for oral administration (~1.9) than for intravenous administration (~1.1). Because the nonlinear pharmacokinetics of DA-6886 was more obviously observed after oral administration, it appears that the saturation of pre-systemic intestinal and/or hepatic first-pass extraction of DA-6886 at high doses occurred.

Current Treatment Options and Therapeutic Insights for Gastrointestinal Dysmotility and Functional Gastrointestinal Disorders

Functional gastrointestinal disorders (FGIDs) have been re-named as disorders of gut-brain interactions. These conditions are not only common in clinical practice, but also in the community. In reference to the Rome IV criteria, the most common FGIDs, include functional dyspepsia (FD) and irritable bowel syndrome (IBS). Additionally, there is substantial overlap of these disorders and other specific gastrointestinal motility disorders, such as gastroparesis. These disorders are heterogeneous and are intertwined with several proposed pathophysiological mechanisms, such as altered gut motility, intestinal barrier dysfunction, gut immune dysfunction, visceral hypersensitivity, altered GI secretion, presence and degree of bile acid malabsorption, microbial dysbiosis, and alterations to the gut-brain axis. The treatment options currently available include lifestyle modifications, dietary and gut microbiota manipulation interventions including fecal microbiota transplantation, prokinetics, antispasmodics, laxatives, and centrally and peripherally acting neuromodulators. However, treatment that targets the pathophysiological mechanisms underlying the symptoms are scanty. Pharmacological agents that are developed based on the cellular and molecular mechanisms underlying pathologies of these disorders might provide the best avenue for future pharmaceutical development. The currently available therapies lack long-term effectiveness and safety for their use to treat motility disorders and FGIDs. Furthermore, the fundamental challenges in treating these disorders should be defined; for instance, 1. Cause and effect cannot be disentangled between symptoms and pathophysiological mechanisms due to current therapies that entail the off-label use of medications to treat symptoms. 2. Despite the knowledge that the microbiota in our gut plays an essential part in maintaining gut health, their exact functions in gut homeostasis are still unclear. What constitutes a healthy microbiome and further, the precise definition of gut microbial dysbiosis is lacking. More comprehensive, large-scale, and longitudinal studies utilizing multi-omics data are needed to dissect the exact contribution of gut microbial alterations in disease pathogenesis. Accordingly, we review the current treatment options, clinical insight on pathophysiology, therapeutic modalities, current challenges, and therapeutic clues for the clinical care and management of functional dyspepsia, gastroparesis, irritable bowel syndrome, functional constipation, and functional diarrhea.

Lactobacillus rhamnosus GG supernatant promotes intestinal mucin production through regulating 5-HT4R and gut microbiota

LGGs promoted intestinal MUC2 production through regulating S100A10/5-HT4R and the gut microbiota.

Review article: diagnosis, management and patient perspectives of the spectrum of constipation disorders

BACKGROUND

Chronic constipation is a common, heterogeneous disorder with multiple symptoms and pathophysiological mechanisms. Patients are often referred to a gastroenterology provider after laxatives fail. However, there is limited knowledge of the spectrum and management of constipation disorders.

AIM

To discuss the latest understanding of the spectrum of constipation disorders, tools for identifying a pathophysiologic-based diagnosis in the specialist setting, treatment options and the patient's perspective of constipation.

METHODS

Literature searches were conducted using PubMed for constipation diagnostic criteria, diagnostic tools and approved treatments. The authors provided insight from their own practices.

RESULTS

Clinical assessment, stool diaries and Rome IV diagnostic criteria can facilitate diagnosis, evaluate severity and distinguish between IBS with constipation, chronic idiopathic constipation and dyssynergic defecation. Novel smartphone applications can help track constipation symptoms. Rectal examinations, anorectal manometry and balloon expulsion, assessments of neuromuscular function with colonic transit time and colonic manometry can provide mechanistic understanding of underlying pathophysiology. Treatments include lifestyle and diet changes, biofeedback therapy and pharmacological agents. Several classes of laxatives, as well as prokinetic and prosecretory agents, are available; here we describe their mechanisms of action, efficacy and side effects.

CONCLUSIONS

Constipation includes multiple overlapping subtypes identifiable using detailed history, current diagnostic tools and smartphone applications. Recognition of individual subtype(s) could pave the way for optimal, evidence-based treatments by a gastroenterology provider.

Current Overview on Clinical Management of Chronic Constipation

Constipation is one of the major gastrointestinal disorders diagnosed in clinical practice in Western countries. Almost 20% of population suffer from this disorder, which means constipation is a substantial utilization of healthcare. Pathophysiology of constipation is complex and multifactorial, where aspects like disturbance in colonic transit, genetic predisposition, lifestyle habits, psychological distress, and many others need to be taken into consideration. Diagnosis of constipation is troublesome and requires thorough accurate examination. A nonpharmacological approach, education of the patient about the importance of lifestyle changes like diet and sport activity state, are the first line of therapy. In case of ineffective treatment, pharmacological treatments such as laxatives, secretagogues, serotonergic agonists, and many other medications should be induced. If pharmacologic treatment fails, the definitive solution for constipation might be surgical approach. Commonness of this disorder, costs of medical care and decrease in quality life cause constipation is a serious issue for many specialists. The aim of this review is to present current knowledge of chronic constipation and management of this disorder.

Diagnosis and treatment of constipation: a clinical update based on the Rome IV criteria

The aim of this study was to evaluate the published professional association guidelines regarding the current diagnosis and treatment of functional intestinal constipation in adults and to compare those guidelines with the authors’ experience to standardize actions that aid clinical reasoning and decision-making for medical professionals. A literature search was conducted in the Medline/PubMed, Scielo, EMBASE and Cochrane online databases using the following terms: chronic constipation, diagnosis, management of chronic constipation, Roma IV and surgical treatment. Conclusively, chronic intestinal constipation is a common condition in adults and occurs most frequently in the elderly and in women. Establishing a precise diagnosis of the physiopathology of functional chronic constipation is complex and requires many functional tests in refractory cases. An understanding of intestinal motility and the defecatory process is critical for the appropriate management of chronic functional intestinal constipation, with surgery reserved for cases in which pharmacologic intervention has failed. The information contained in this review article is subject to the critical evaluation of the medical specialist responsible for determining the action plan to be followed within the context of the conditions and clinical status of each individual patient.

Different doses of prucalopride in treating chronic idiopathic constipation: a meta-analysis and Bayesian analysis

OBJECTIVE

This study aims to explore the incremental benefit of different doses of prucalopride in treating chronic idiopathic constipation (CIC).

METHODS

PubMed, EMBASE, MEDLINE, Cochrane Library, Chinese Biomedical Database, China National Knowledge Infrastructure, VIP medicine information and Wanfang databases were comprehensively searched up to March 2020. Prospective trials with different doses of prucalopride versus placebo were selected. The frequency of spontaneous bowel movements (SBMs) per week and the treatment-emergent adverse events (TEAEs), such as headache, arrhythmia, diarrhoea, dizziness, nausea and vomiting, were first synthesised in a meta-analysis. The probability of optimal dose of prucalopride was then ranked by random-effects within Bayesian analysis.

RESULTS

14 high-quality randomised controlled trials with 4328 patients were ultimately included. SBMs per week increased significantly after using 1 mg (OR: 2.40, 95% CI 1.32 to 4.37), 2 mg (OR: 2.55, 95% CI 1.93 to 3.36) and 4 mg (OR: 2.51, 95% CI 1.92 to 3.28) prucalopride. Bayesian analysis demonstrated 1 mg dose obtained the maximum SBMs per week (OR: 3.31, 95% credible interval 1.72 to 6.16, probability rank=0.70) indirectly compared with 2 mg and 4 mg doses. TEAEs were higher significantly in 2 mg (risk ratio (RR): 1.20, 95% CI 1.09 to 1.33) and 4 mg (RR: 1.14, 95% CI 1.07 to 1.22) prucalopride. The 1 mg dose did not reach statistical significance (RR: 1.17, 95% CI 0.94 to 1.44).

CONCLUSIONS

The study concludes that 1 mg dose at commencement could be safer in treating CIC and that 2 mg prucalopride could be more efficacious in terms of SBMs per week outcome receiving.

PROSPERO REGISTRATION NUMBER

CRD42019136679.

Paracellular Filtration Secretion Driven by Mechanical Force Contributes to Small Intestinal Fluid Dynamics

Studies of fluid secretion by the small intestine are dominated by the coupling with ATP-dependent generation of ion gradients, whereas the contribution of filtration secretion has been overlooked, possibly by the lack of a known mechanistic basis. We measured apical fluid flow and generation of hydrostatic pressure gradients by epithelia of cultured mouse enterocytes, Caco-2 and T-84 cells, and fibroblasts exposed to mechanical force provided by vigorous aeration and in response to ion gradients, inhibitors of ion channels and transporters and in vitro using intact mouse and rat small intestine. We describe herein a paracellular pathway for unidirectional filtration secretion that is driven by mechanical force, requires tight junctions, is independent of ionic and osmotic gradients, generates persistent hydrostatic pressure gradients, and would contribute to the fluid shifts that occur during digestion and diarrhea. Zinc inhibits the flow of fluid and the paracellular marker fluorescein isothyocyanate conjugated dextran (MW = 4 kD) across epithelia of cultured enterocytes (>95%; p < 0.001) and intact small intestine (>40%; p = 0.03). We propose that mechanical force drives fluid secretion through the tight junction complex via a “one-way check valve” that can be regulated. This pathway of filtration secretion complements chloride-coupled fluid secretion during high-volume fluid flow. The role of filtration secretion in the genesis of diarrhea in intact animals needs further study. Our findings may explain a potential linkage between intestinal motility and intestinal fluid dynamics.

ASBT(SLC10A2): A promising target for treatment of diseases and drug discovery

Bile acids has gradually become a new focus in various diseases, and ASBT as a transporter responsible for the reabsorption of ileal bile acids, is a key hinge associated to the bile acids-cholesterol balance and bile acids of enterohepatic circulation. The cumulative studies have also shown that ASBT is a promising target for treatment of liver, gallbladder, intestinal and metabolic diseases. This article briefly reviewed the process of bile acids enterohepatic circulation, as well as the regulations of ASBT expression, covering transcription factors, nuclear receptors and gut microbiota. In addition, the relationship between ASBT and various diseases were discussed in this paper. According to the structural classification of ASBT inhibitors, the research status of ASBT inhibitors and potential ASBT inhibitors of traditional Chinese medicine (such resveratrol, jatrorrhizine in Coptis chinensis) were summarized. This review provides a basis for the development of ASBT inhibitors and the treatment strategy of related diseases.

Application of the Nested Enzyme-Within-Enterocyte (NEWE) Turnover Model for Predicting the Time Course of Pharmacodynamic Effects

The gut wall consists of many biological elements, including enterocytes. Rapid turnover, a prominent feature of the enterocytes, has generally been ignored in the development of enterocyte-targeting drugs, although it has a comparable rate to other kinetic rates. Here, we investigated the impact of enterocyte turnover on the pharmacodynamics of enterocyte-targeting drugs by applying a model accounting for turnover of enterocytes and target proteins. Simulations showed that the pharmacodynamics depend on enterocyte lifespan when drug-target affinity is strong and half-life of target protein is long. Interindividual variability of enterocyte lifespan, which can be amplified by disease conditions, has a substantial impact on the variability of response. However, our comprehensive literature search showed that the enterocyte turnover causes a marginal impact on currently approved enterocyte-targeting drugs due to their relatively weak target affinities. This study proposes a model-informed drug development approach for selecting enterocyte-targeting drugs and their optimal dosage regimens.

Study of defecation disorders in elderly patients

Introduction Defecation disorders, whether anal incontinence or chronic intestinal constipation, are frequent pelvic floor alterations in the general population and are more common in those with risk factors,i.e., in the elderly, women with an obstetric background, and those with comorbidities, history of pelvic radiotherapy, diabetics, the bedridden, or those with history of orifice surgery, among others.

Objective To analyze the incidence of defecation disorders in geriatric patients treated at the Medical Specialties Outpatient Service (MSOS) of Hospital Santa Marcelina.

Methods Prospective, randomized study that interviewed the same patients in two moments: 1) subjective anamnesis through spontaneous history and 2) objective anamnesis with specific questionnaires to assess anal incontinence and chronic constipation.

Results Between March 2016 and June 2017, 149 patients were analyzed, of whom 114 (76.5%) were female, with a similar mean age between genders; 51.67% had symptoms of anal incontinence and/or chronic constipation. Only 35.5% of patients with complaints of fecal leakage or flatus spontaneously reported them, while 87.1% of constipated patients did so. In the present study, no significant correlation was observed between the mode of delivery (p = 0.106), pregnancy (p = 0.099), and the number of deliveries (p = 0.126) with anal incontinence. In turn, there was no higher incidence of chronic intestinal constipation in females (p = 0.099) and most patients with this complaint had Bristol type 1 or 2 stools.

Conclusion The incidence of defecation disorders in the geriatric population is high and, most notably, anal incontinence is not spontaneously reported by most patients.

Prevalence and Risk Factors for Opioid-Induced Constipation in an Older National Veteran Cohort

Objectives

This research describes the prevalence and covariates associated with opioid-induced constipation (OIC) in an observational cohort study utilizing a national veteran cohort and integrated data from the Center for Medicare and Medicaid Services (CMS).

Methods

A cohort of 152,904 veterans with encounters between 1 January 2008 and 30 November 2010, an exposure to opioids of 30 days or more, and no exposure in the prior year was developed to establish existing conditions and medications at the start of the opioid exposure and determining outcomes through the end of exposure. OIC was identified through additions/changes in laxative prescriptions, all-cause constipation identification through diagnosis, or constipation related procedures in the presence of opioid exposure. The association of time to constipation with opioid use was analyzed using Cox proportional hazard regression adjusted for patient characteristics, concomitant medications, laboratory tests, and comorbidities.

Results

The prevalence of OIC was 12.6%. Twelve positively associated covariates were identified with the largest associations for prior constipation and prevalent laxative (any laxative that continued into the first day of opioid exposure). Among the 17 negatively associated covariates, the largest associations were for erythromycins, androgens/anabolics, and unknown race.

Conclusions

There were several novel covariates found that are seen in the all-cause chronic constipation literature but have not been reported for opioid-induced constipation. Some are modifiable covariates, particularly medication coadministration, which may assist clinicians and researchers in risk stratification efforts when initiating opioid medications. The integration of CMS data supports the robustness of the analysis and may be of interest in the elderly population warranting future examination.

Drug Discovery and Repurposing Inhibits a Major Gut Pathogen-Derived Oncogenic Toxin

Objective: The human intestinal microbiome plays an important role in inflammatory bowel disease (IBD) and colorectal cancer (CRC) development. One of the first discovered bacterial mediators involves Bacteroides fragilis toxin (BFT, also named as fragilysin), a metalloprotease encoded by enterotoxigenic Bacteroides fragilis (ETBF) that causes barrier disruption and inflammation of the colon, leads to tumorigenesis in susceptible mice, and is enriched in the mucosa of IBD and CRC patients. Thus, targeted inhibition of BFT may benefit ETBF carrying patients. Design: By applying two complementary in silico drug design techniques, drug repositioning and molecular docking, we predicted potential BFT inhibitory compounds. Top candidates were tested in vitro on the CRC epithelial cell line HT29/c1 for their potential to inhibit key aspects of BFT activity, being epithelial morphology changes, E-cadherin cleavage (a marker for barrier function) and increased IL-8 secretion. Results: The primary bile acid and existing drug chenodeoxycholic acid (CDCA), currently used for treating gallstones, cerebrotendinous xanthomatosis, and constipation, was found to significantly inhibit all evaluated cell responses to BFT exposure. The inhibition of BFT resulted from a direct interaction between CDCA and BFT, as confirmed by an increase in the melting temperature of the BFT protein in the presence of CDCA. Conclusion: Together, our results show the potential of in silico drug discovery to combat harmful human and microbiome-derived proteins and more specifically suggests a potential for retargeting CDCA to inhibit the pro-oncogenic toxin BFT.

Luminal 5-HT4 receptors-A successful target for prokinetic actions

The prokinetic effects of 5-HT₄ receptor (5-HT₄ R) agonists have been utilized clinically for almost three decades to relieve symptoms of constipation. Surprisingly, the mechanism(s) of action of these compounds is still being debated. Recent studies highlight luminal 5-HT₄ Rs as an alternative and effective target for these prokinetic agents. These include the study by Shokrollahi et al (2019, Neurogastroenterol Motil, e13598) published in the current issue of Neurogastroenterology and Motility, who found that activation of mucosal 5-HT₄ Rs by intraluminal prucalopride, significantly enhanced propulsive motor patterns in rabbit colon. The authors highlight the idea that development of agonists targeting luminal 5-HT₄ Rs in the colonic mucosa might be more effective and safer in achieving prokinetic effects on intestinal motility. The purpose of this mini-review is to discuss the evidence for luminal 5-HT₄ Rs as an emerging target for prokinetic agents in facilitating propulsive motor patterns in the colon.

Physicochemical properties and laxative effects of polysaccharides from Anemarrhena asphodeloides Bge. in loperamide-induced rats

ETHNOPHARMACOLOGICAL RELEVANCE

As a traditional Chinese herbal medicine, Anemarrhena asphodeloides Bge. possesses the effects of nourishing yin, moistening dryness, clearing lungs and relieving fire. Simultaneously, it has been used to treat constipation for more than one thousand years in China. However, modern medical studies are limited and lacking on its therapeutic mechanism.

AIM OF THE STUDY

This current study was aimed to investigate the laxative activities and explore the potential mechanism of Anemarrhena asphodeloides Bge. polysaccharides (AABP) in loperamide-induced constipation rats.

MATERIALS AND METHODS

The structure of AABP was determined by using infrared spectrum, high performance gel permeation chromatography (HPGPC), and high performance liquid chromatography (HPLC). Real-time quantitative polymerase chain reaction (PCR), multitudinous methods were adopted to explore the underlining therapeutic mechanism of AABP in treating constipation, including enzyme-linked immunosorbent assay (ELISA), histopathological, immunohistochemistry and western blotting.

RESULTS

In the present study, the average molecular weight of AABP was determined as 1.11 × 10³ kDa. The primary monosaccharide compositions were analyzed including D-mannose, L-rhamnose, D-galacturonic acid, D-glucose, D-galactose and L-arabinose (1, 0.04, 0.53, 0.11, 0.33, 0.25, respectively) by high-performance liquid chromatography (HPLC). AABP significantly increased the levels of gastrin (Gas), motilin (MTL), substance P (SP), 5-hydroxytryptamine (5-HT) and vasoactive intestinal peptide (VIP), and decreased the NO content of loperamide-induced rats to ameliorate constipation in the rats. Whilst, AABP repaired the damaged colons by regulating PCNA and ICAM-1 protein expressions. Additionally, AABP up-regulated the levels of SCF, c-Kit, AQP3 and VIP as well as down-regulated the expressions of AQP8, AQP4 and PGE2.

CONCLUSION

The present findings suggested that AABP were the laxative active ingredients isolated from Anemarrhena asphodeloides Bge., which could treat constipation through regulating the gastrointestinal hormones and neurotransmitters to improve the intestinal motility and water metabolism.

Advances in understanding relationship between 5-hydroxytryptamine and its receptors and intestinal dysmotility in irritable bowel syndrome

Irritable bowel syndrome (IBS) is a common clinical functional gastrointestinal disease, which seriously affects the quality of life of patients. The pathogenesis of this disorder is unclear and may be related to the changes of visceral sensitivity, gastrointestinal motility, and the function of the brain-gut axis. 5-hydroxytryptamine (5-HT) is an important neurotransmitter, which exhibits a variety of biological effects including gastrointestinal secretion and motility regulation by binding to its receptors. The changes in the synthesis and release of 5-HT and in the expression and function of corresponding receptors are all involved in the pathophysiological process of IBS. In this paper, we will review the role of 5-HT and its receptors in intestinal dysmotility in IBS.

Low fermentable oligosaccharides, disaccharides, monosaccharides, and polypols diet and irritable bowel syndrome in Asia

Functional bowel disorders, including irritable bowel syndrome (IBS), are a chronic condition that can significantly reduce patients' quality of life. Therefore, this paper will review the roles of a low fermentable oligosaccharides, disaccharides, monosaccharides, and polypols (FODMAP) diet in treating IBS, particularly in an Asian setting. About 20% of the general population is diagnosed with IBS. However, there are limited effective medical therapies available for treating IBS. Therefore, IBS presents a major challenge to the health-care providers. Recently, there is an increasing interest in the use of a diet low in FODMAP for the treatment of IBS. A low FODMAP diet can decrease the delivery of readily fermentable substrates to the small intestine and colon, thereby improving functional gastrointestinal symptoms.

Home-Based Transcutaneous Neuromodulation Improved Constipation via Modulating Gastrointestinal Hormones and Bile Acids

This study aims to investigate the role of transcutaneous neuromodulation (TN) on the regulation of gastrointestinal hormones and bile acids in patients with functional constipation (FC). Twenty FC patients were treated with TN for four weeks. The effects of TN on symptoms were evaluated by questionnaires. Plasma levels of serotonin (5-HT), motilin, somatostatin, and vasoactive intestinal peptide (VIP) were measured by ELISA and 12 individual bile acids assayed by liquid chromatography tandem mass spectrometry. Results were as follows. (1) TN treatment increased the frequency of spontaneous bowel movement, improved the Bristol Stool Score, and reduced Patient Assessment of Constipation Symptom score and Patient Assessment of Constipation Quality of Life score. (2) FC patients showed decreased plasma levels of 5-HT, motilin, and VIP and an increased plasma level of somatostatin (P < 0.05). Four-week TN treatment increased plasma levels of 5-HT and motilin and decreased the plasma level of somatostatin in the FC patients (P < 0.05). (3) Taurocholic deoxycholate, taurocholic acid, and taurocholic lithocholic acid were increased in the FC patients (P < 0.005) but reduced by TN treatment (P < 0.05). This study has suggested that the therapy may improve the symptoms of FC by alleviating the disorders of gastrointestinal hormones and bile acids.

Cellular mechanism for herbal medicine Junchoto to facilitate intestinal Cl-/water secretion that involves cAMP-dependent activation of CFTR

Constipation is a common symptom frequently compromising the quality of daily life. Several mechanistically different drugs have been used to mitigate constipation, including Japanese herbal (Kampo) medicines. However, the mechanisms of their actions are often not well understood. Here we aimed to investigate the molecular mechanisms underlying the effects of Junchoto (JCT), a Kampo medicine empirically prescribed for chronic constipation. Cl⁻ channel activity was measured by the patch-clamp method in human cystic fibrosis transmembrane conductance regulator (CFTR)-expressing HEK293T cells and human intestinal Caco-2 cells. cAMP was measured by a luciferase-based assay. Cell volume change was measured by a particle-sizing and particle-counting analyzer and video-microscopic measurement. In both CFTR-expressing HEK293T and Caco-2 cells, JCT dose-dependently induced whole-cell currents showing typical biophysical and pharmacological features of CFTR. Robust expression of CFTR was confirmed by RT-PCR and Western blotting in Caco-2 cells. Luciferase-based measurement revealed that JCT increases intracellular cAMP levels. Administration of the adenylate cyclase inhibitor SQ22536 or CFTR inhibitor-172, or treatment with small interfering RNAs (siRNA) targeting CFTR, abolished JCT-induced whole-cell currents, suggesting that elevated intracellular cAMP by JCT causes activation of CFTR in Caco-2 cells. Finally, blockade of CFTR activity by CFTR inhibitor-172 or siRNA-knockdown of CFTR or application of SQ22536 markedly reduced the degree of cell volume decrease induced by JCT. JCT can induce a Cl⁻ efflux through the CFTR channel to promote water secretion, and this effect is likely mediated by increased cAMP production.

The novel, potent and highly selective 5-HT4 receptor agonist YH12852 significantly improves both upper and lower gastrointestinal motility

BACKGROUND AND PURPOSE

5-HT₄ receptor agonists have been shown to be effective at treating various gastrointestinal tract disorders. However, a lack of selectivity against off-targets has been a limiting factor for their clinical use.

EXPERIMENTAL APPROACH

The binding affinity and selectivity of YH12852 for human 5-HT_4(a) receptor in CHO-K1 cells were evaluated using radioligand binding assays, and agonistic activity was assessed using a β-lactamase reporter system. Contractile activity and propulsive motility were measured in the guinea pig isolated distal colon. Its prokinetic effect on the gastrointestinal tract was evaluated in guinea pigs, dogs and monkeys. Its tissue distribution was evaluated in rats.

KEY RESULTS

YH12852 exhibited high affinity and potency for human recombinant 5-HT_4(a) receptor with high selectivity over other 5-HT and non-5-HT receptors, ion channels, enzymes and transporters. YH12852 induced contractions and increased propulsive motility in guinea pig isolated colon. These effects were abolished by the 5-HT₄ receptor antagonist GR113808. YH12852 increased defecation more effectively than prucalopride in guinea pigs and dogs and improved gastric emptying more effectively than mosapride in guinea pigs, dogs and monkeys. YH12852 was highly distributed to the gastrointestinal tract as the target organ.

CONCLUSION AND IMPLICATIONS

The high in vitro potency and selectivity of YH12852 for 5-HT₄ receptor translated into potent in vivo efficacy with good tolerability. YH12852 significantly improved both upper and lower bowel motility in the animal models tested and has the potential to address considerable unmet needs in patients with functional constipation, gastroparesis or both.

Irritable bowel syndrome in Asia: Pathogenesis, natural history, epidemiology, and management

Historically, the epidemiology of gastrointestinal diseases in Asia was different from that in Western countries. Early studies suggested a low prevalence of irritable bowel syndrome (IBS) in Asia. As the diagnosis of IBS is symptom-based and as symptom perception, expression, and interpretation are influenced by sociocultural perspectives including language, the presentation of IBS is expected to vary in different communities. Furthermore, the pathogenesis is multifactorial with psychosocial (stress, illness, behavior, and diet) and biological (infection, gut microbiota, and immune activation) variables interacting, and so, the present study can anticipate that the development of IBS will vary in different environments. In recognition of this aspect of functional gastrointestinal disorders, the recently published Rome IV documents have provided greater focus on cross-cultural factors. In this review, the present study seeks to highlight Asian perspectives by identifying historical trends and recent publications from the region and comparing these with the observations from Western societies.

Constipation management in people with intellectual disability: A systematic review

BACKGROUND

Constipation can lead to serious health issues and death. This systematic review summarizes international research pertaining to the management of constipation in people with intellectual disability.

METHOD

Studies published from 1990 to 2017 were identified using Medline, Cinahl, PsycINFO, Web of Science, email requests and cross-citations. Studies were reviewed narratively in relation to identified themes.

RESULTS

Eighteen studies were reviewed in relation to three themes: laxative receipt; interventions (dietary fibre, abdominal massage and macrogol); and staff issues (knowledge and training). Laxative polypharmacy was common. Studies report positive results for dietary fibre and abdominal massage although study quality was limited.

CONCLUSION

The main management response to constipation in people with intellectual disability is laxative use despite limited effectiveness. An improved evidence base is required to support the suggestion that an individualized, integrated bowel management programme may reduce constipation and associated health conditions in people with intellectual disability.

New therapeutic perspectives in irritable bowel syndrome: Targeting low-grade inflammation, immuno-neuroendocrine axis, motility, secretion and beyond

Irritable bowel syndrome (IBS) is a chronic, recurring, and remitting functional disorder of the gastrointestinal tract characterized by abdominal pain, distention, and changes in bowel habits. Although there are several drugs for IBS, effective and approved treatments for one or more of the symptoms for various IBS subtypes are needed. Improved understanding of pathophysiological mechanisms such as the role of impaired bile acid metabolism, neurohormonal regulation, immune dysfunction, the epithelial barrier and the secretory properties of the gut has led to advancements in the treatment of IBS. With regards to therapies for restoring intestinal permeability, multiple studies with prebiotics and probiotics are ongoing, even if to date their efficacy has been limited. In parallel, much progress has been made in targeting low-grade inflammation, especially through the introduction of drugs such as mesalazine and rifaximin, even if a better knowledge of the mechanisms underlying the low-grade inflammation in IBS may allow the design of clinical trials that test the efficacy and safety of such drugs. This literature review aims to summarize the findings related to new and investigational therapeutic agents for IBS, most recently developed in preclinical as well as Phase 1 and Phase 2 clinical studies.

Localization of the 5-hydroxytryptamine 4 receptor in equine enteric neurons and extrinsic sensory fibers

BACKGROUND

Serotonin plays a pivotal role in regulating gut motility, visceral sensitivity, and fluid secretion via specific receptors. Among these receptors, 5-HT₄ exerts a prominent control on gut motor function. Although the prokinetic effect exerted by 5-HT₄ agonists is well known, the cellular sites of 5-HT₄ expression remain poorly understood in large mammals, e.g., horses. In this study, we evaluated the distribution of 5-HT₄ in the horse intestine and in foals with enteric aganglionosis, reminiscent of human Hirschsprung's disease.

METHODS

The intestine and spinal ganglia were obtained from three healthy horses and two foals with hereditary ileocolonic aganglionosis. Tissues were processed for immunohistochemistry using a specific antibody to 5-HT₄ and a variety of neuronal markers. Myenteric and submucosal plexus 5-HT₄ -immunoreactive (IR) neurons were quantified as relative percentage (mean±SD) to the total number of neurons counted. Furthermore, the density of 5-HT₄ -IR nerve fibers was evaluated in the mucosa and tunica muscularis.

KEY RESULTS

The 5-HT₄ immunoreactivity was localized to large percentages of myenteric neurons ranging from 28±9% (descending colon) to 63±19% (ileum), and submucosal neurons ranging from 54±6% (ileum) to 68±14% (duodenum). The 5-HT₄ -immunoreactivity was co-expressed by some substance P-IR (SP-IR) spinal ganglion neurons and extrinsic sensory fibers of aganglionic foals.

CONCLUSIONS & INFERENCES

The presence of 5-HT₄ in many enteric and extrinsic sensory neurons and nerve fibers provides solid morphological evidence of the cellular sites of 5-HT₄ expression in horses. The evidence of SP-IR sensory neurons positive for 5-HT₄ suggests its role in visceral sensitivity.

Luminally Acting Agents for Constipation Treatment: A Review Based on Literatures and Patents

Constipation is one of the most frequently reported gastrointestinal (GI) disorders that negatively impacts quality of life and is associated with a significant economic burden to the patients and society. Traditional treatments including lifestyle modification and laxatives are often ineffective in the more severe forms of constipation and over the long term. New medications targeting at intestinal chloride channels and colonic serotonin receptors have been demonstrated effective in recent years. Emerging agents focusing on improving intestinal secretion and/or colonic motility have been shown effective in animal models and even in clinical trials. Recognization of the role of cystic fibrosis transmembrane regulator (CFTR) and calcium-activated chloride channels (CaCCs) in intestine fluid secretion and motility modulation makes CFTR and CaCCs promising molecule targets for anti-constipation therapy. Although there are multiple choices for constipation treatment, there is still a recognized need for new medications in anti-constipation therapy. The present review covers the discovery of luminally acting agents for constipation treatment described in both patents (2011–present) and scientific literatures.

Mashiningan Improves Opioid-Induced Constipation in Rats by Activating Cystic Fibrosis Transmembrane Conductance Regulator Chloride Channel

Opioid receptor stimulants are analgesics used in patients with and without cancer; however, they often cause constipation, resulting in poor adherence and deterioration of the quality of life. Hence, suitable treatments for constipation are required. In this study, we investigated the pharmacological mechanisms of action of mashiningan (MNG), a Kampo medicine used to treat constipation, and evaluated the effect of MNG on opioid-induced constipation in rats. MNG (100 or 300 mg/kg) was orally administered to normal or codeine phosphate (CPH)-induced constipation in rats, and its effect was evaluated on the basis of fecal counts, characteristics, and weight. Small intestinal fluid secretion was measured after treatment with MNG alone or coadministration with a cystic fibrosis transmembrane conductance regulator (CFTR)-specific inhibitor (CFTRinh-172). The effects of MNG on the CFTR and type-2 chloride channel were determined using patch-clamp or short-circuit current experiments, respectively. MNG increased the fecal weight and proportion of soft feces in normal rats. CPH-induced constipation in rats decreased fecal counts and weight, whereas MNG prevented these effects and increased the proportion of soft feces. MNG increased the electronic chloride current, and this effect was inhibited by the CFTRinh-172 in the CFTR assay. Furthermore, MNG increased small intestinal fluid secretion, and this effect was abolished by coadministration with the CFTRinh-172. MNG improved opioid-induced constipation in rats, and this improvement may have been mediated by increasing intestinal fluid secretion via CFTR chloride channel activation. Therefore, MNG is expected as a medicine of the treatment of constipation in patients taking opioids.

Effects of Hwangryunhaedok-tang on gastrointestinal motility function in mice

AIM

To investigate the effects of Hwangryunhaedok-tang (HHT) on gastrointestinal (GI) motility in mice.

METHODS

The effects of a boiling water extract of HHT (HHTE) on GI motility were investigated by calculating percent intestinal transit rates (ITR%) and gastric emptying (GE) values using Evans Blue and phenol red, respectively, in normal mice and in mice with experimentally induced GI motility dysfunction (GMD). In addition, the effects of the four components of HHT, that is, Gardeniae Fructus (GF), Scutellariae Radix (SR), Coptidis Rhizoma (CR), and Phellodendri Cortex (PC), on GI motility were also investigated.

RESULTS

In normal ICR mice, ITR% and GE values were significantly and dose-dependently increased by the intragastric administration of HHTE (0.1-1 g/kg). The ITR% values of GMD mice were significantly lower than those of normal mice, and these reductions were significantly and dose-dependently inhibited by HHTE (0.1-1 g/kg). Additionally, GF, CR, and PC dose-dependently increased ITR% and GE values in normal and GMD mice.

CONCLUSION

These results suggest that HHT is a novel candidate for the development of a gastroprokinetic agent for the GI tract.

Pharmacological Approach for Managing Pain in Irritable Bowel Syndrome: A Review Article

Context

Visceral pain is a leading symptom for patients with irritable bowel syndrome (IBS) that affects 10% - 20 % of the world population. Conventional pharmacological treatments to manage IBS-related visceral pain is unsatisfactory. Recently, medications have emerged to treat IBS patients by targeting the gastrointestinal (GI) tract and peripheral nerves to alleviate visceral pain while avoiding adverse effects on the central nervous system (CNS). Several investigational drugs for IBS also target the periphery with minimal CNS effects.

Evidence of Acquisition

In this paper, reputable internet databases from 1960 - 2016 were searched including Pubmed and ClinicalTrials.org, and 97 original articles analyzed. Search was performed based on the following keywords and combinations: irritable bowel syndrome, clinical trial, pain, visceral pain, narcotics, opioid, chloride channel, neuropathy, primary afferent, intestine, microbiota, gut barrier, inflammation, diarrhea, constipation, serotonin, visceral hypersensitivity, nociceptor, sensitization, hyperalgesia.

Results

Certain conventional pain managing drugs do not effectively improve IBS symptoms, including NSAIDs, acetaminophen, aspirin, and various narcotics. Anxiolytic and antidepressant drugs (Benzodiazepines, TCAs, SSRI and SNRI) can attenuate pain in IBS patients with relevant comorbidities. Clonidine, gabapentin and pregabalin can moderately improve IBS symptoms. Lubiprostone relieves constipation predominant IBS (IBS-C) while loperamide improves diarrhea predominant IBS (IBS-D). Alosetron, granisetron and ondansetron can generally treat pain in IBS-D patients, of which alosetron needs to be used with caution due to cardiovascular toxicity. The optimal drugs for managing pain in IBS-D and IBS-C appear to be eluxadoline and linaclotide, respectively, both of which target peripheral GI tract.

Conclusions

Conventional pain managing drugs are in general not suitable for treating IBS pain. Medications that target the GI tract and peripheral nerves have better therapeutic profiles by limiting adverse CNS effects.

Development of a mechanism-based pharmacokinetic/pharmacodynamic model to characterize the thermoregulatory effects of serotonergic drugs in mice

We have shown recently that concurrent harmaline, a monoamine oxidase-A inhibitor (MAOI), potentiates serotonin (5-HT) receptor agonist 5-methoxy-N,N-dimethyltryptamine (5-MeO-DMT)-induced hyperthermia. The objective of this study was to develop an integrated pharmacokinetic/pharmacodynamic (PK/PD) model to characterize and predict the thermoregulatory effects of such serotonergic drugs in mice. Physiological thermoregulation was described by a mechanism-based indirect-response model with adaptive feedback control. Harmaline-induced hypothermia and 5-MeO-DMT–elicited hyperthermia were attributable to the loss of heat through the activation of 5-HT_1A receptor and thermogenesis via the stimulation of 5-HT_2A receptor, respectively. Thus serotonergic 5-MeO-DMT–induced hyperthermia was readily distinguished from handling/injection stress-provoked hyperthermic effects. This PK/PD model was able to simultaneously describe all experimental data including the impact of drug-metabolizing enzyme status on 5-MeO-DMT and harmaline PK properties, and drug- and stress-induced simple hypo/hyperthermic and complex biphasic effects. Furthermore, the modeling results revealed a 4-fold decrease of apparent SC₅₀ value (1.88–0.496 µmol/L) for 5-MeO-DMT when harmaline was co-administered, providing a quantitative assessment for the impact of concurrent MAOI harmaline on 5-MeO-DMT–induced hyperthermia. In addition, the hyperpyrexia caused by toxic dose combinations of harmaline and 5-MeO-DMT were linked to the increased systemic exposure to harmaline rather than 5-MeO-DMT, although the body temperature profiles were mispredicted by the model. The results indicate that current PK/PD model may be used as a new conceptual framework to define the impact of serotonergic agents and stress factors on thermoregulation.

Patient considerations in the management of chronic constipation: focus on prucalopride

Chronic constipation is a common condition that significantly impacts health care utilization, productivity, and quality of life. Laxatives are commonly used, although often insufficient in restoring normal bowel function or providing adequate relief. There remains a significant need for the development of novel agents to optimize treatment of this condition. This review provides an overview of the preclinical and clinical trial data, supporting the efficacy and safety of prucalopride, a highly selective 5-HT4 receptor agonist that has been approved by the European Medicine Agency for the treatment of chronic constipation in adults who have failed standard laxative therapy. Unlike older 5-HT4 agonists, prucalopride has not been associated with adverse cardiovascular side effects or QT prolongation owing to its high selectivity and affinity for the 5-HT4 receptor without clinically significant cross-reactivity at the human ether-à-go-go-related gene (hERG) potassium channel or 5-HT receptor subtypes that have previously been implicated in adverse cardiovascular events and arrhythmias. Careful safety assessments have documented the relative safety and tolerability of this agent in various patient groups. Focus has also been placed on demonstrating efficacy with regard to bowel function, symptoms, and patient-reported outcomes such as the Patient Assessment of Constipation-Symptoms and the Patient Assessment of Constipation Quality of Life scores to support the use of prucalopride as a safe and effective therapeutic option for the management of chronic constipation.