Emerging pharmacologic therapies for irritable bowel syndrome

Daikenchuto significantly improves stool consistency and lower gastrointestinal symptoms in patients with chronic constipation

Background and Aim

A number of basic and clinical studies have confirmed that the traditional Japanese herbal medicine, Daikenchutou (DKT) has a pharmacological effect on cholinergic and serotonergic mechanisms with a favorable safety profile and an improving effect on lower gastrointestinal (GI) symptoms including abdominal pain or bloating. The purpose of this study is to evaluate the efficacy and safety of DKT on chronic constipation.

Methods

This multicenter, randomized, placebo-controlled, double-blinded clinical trial enrolled 67 patients with chronic constipation fulfilling Rome III criteria. After a 2-week observation period, 63 patients with persistent symptoms were finally randomized to a 4-week course of treatment with DKT or placebo. The primary endpoint consisted of a global assessment of overall treatment effect (OTE), while the secondary endpoints consisted of improvements in stool consistency, spontaneous bowel movements, lower GI symptoms related to constipation, and quality of life. Factors associated with OTE were also investigated.

Results

After 4 weeks administration of DKT, OTE was significantly higher than placebo. No side effects were observed. Significant improvement in stool consistency and lower GI symptoms was observed in the DKT group. The improvements in lower GI symptoms as well as stool consistency were associated with OTE. OTE was higher in patients with greater improvement in lower GI symptoms with mental component summary scores close to normal before treatment.

Conclusion

DKT was effective and safe in treating chronic constipation, especially in patients having symptoms related to constipation with no impaired mental component summary score.

Shaoyao-Gancao Decoction Relieves Visceral Hyperalgesia in TNBS-Induced Postinflammatory Irritable Bowel Syndrome via Inactivating Transient Receptor Potential Vanilloid Type 1 and Reducing Serotonin Synthesis

Postinflammatory irritable bowel syndrome (PI-IBS) is a common functional gastrointestinal disorder, which is characterized by abdominal pain, low-grade inflammation, and visceral hypersensitivity. Shaoyao-Gancao decoction (SGD) has been used to improve the clinical symptoms of abdominal spasmodic pain accompanying acute gastroenteritis, but the underlying therapeutic mechanism has not been fully elucidated. In the present study, a rat model of PI-IBS was established via rectal administration of TNBS. Rats were scored daily for 28 days using disease activity index (DAI). Abdominal withdrawal reflex (AWR) was used to measure the pain threshold. After SGD (6.25, 12.5, and 25 g/kg/d) treatment for 14 days, rat colonic tissue was collected for histopathological grading, enterochromaffin (EC) cell count, and 5-HT content measurement. RT-qPCR and western blot analyses were employed to detect the gene and protein level of tryptophan hydroxylase (TPH), serotonin reuptake transporter (SERT), and transient receptor potential vanilloid 1 (TRPV1). To further validate the effect of SGD on TRPV1, another experiment was performed in cells. The results revealed that visceral hyperalgesia, reflected by increased DAI, AWR, pathological injury score, 5-HT content, and EC cell count in PI-IBS rats, was significantly ameliorated by SGD. In cells, SGD markedly inhibited the expression and function of TRPV1. Moreover, the expression levels of TPH were also repressed by SGD. The findings of the present study indicated that the therapeutic effect of SGD on visceral hyperalgesia may be closely associated with the regulatory role of TRPV1 and 5-HT signaling pathways.

'New/Designer Benzodiazepines': An Analysis of the Literature and Psychonauts' Trip Reports

BACKGROUND

NPS belonging to the benzodiazepine (BZD) class, e.g., 'legal/designer BZDs'/'research chemicals', have recently emerged in the drug (mainly online/virtual) market.

OBJECTIVE

While certain NPS belonging to the BZD class possess pharmacological profiles similar to controlled pharmaceutical BZDs, clinical and pharmacological profiles of current emerging BZDs are still not well-described. Therefore, there is a need to increase clinicians'/public health knowledge/awareness, to incentive harm reduction strategies.

METHOD

A comprehensive overview was carried out by using the EMCDDA/EDND database regularly monitored by our research team, by specifically looking at the 'new BZDs' so far notified. Furthermore, given the limitation of peer-reviewed data published so far, a nonparticipant multilingual qualitative netnographic study was conducted to obtain further clinical/pharmacological/ toxicological data, including psychonauts' online trip reports.

RESULTS

First designer BZDs appeared as NPS around 2007. So far, 29 designer BZDs have been notified to the EMCDDA, being some of them extremely powerful, also at lower dosages. They are sold as tablets/powder/pellets/capsules/blotters/liquids, at very affordable prices, and variably administered. Some are also sold on the illicit drugmarket as counterfeit forms of traditional BZDs or as either adulterants or diluents in heroin or other synthetic opioids/cannabinoids. Nowadays, there is no guarantee of the quality of designer BZDs composition/purification and, hence, most NPS consumers may be inadvertently exposed to unsafe and harmful compounds.

CONCLUSION

Given the limited information on their pharmacology/toxicity, variations in dosage, onset of effects, combination of substances, potency, and general patient or individual variability, the concomitant use of these substances with other drugs entails several and unpredictable risks.

Plecanatide: a new guanylate cyclase agonist for the treatment of chronic idiopathic constipation

Chronic constipation affects millions of Americans, consumes significant healthcare resources, and significantly affects quality of life (QOL). Recently, several new treatment options have become available for the treatment of constipation, including intestinal secretagogues such as lubiprotone, and linaclotide, prokinetics such as prucalopride, and bile acid transporter antagonists. Plecanatide is the newest of the secretagogue class of compounds that has been approved by the US Food and Drug Administration for the treatment of adults with chronic idiopathic constipation (CIC) in the USA. It is a guanylate cyclase agonist, and a 16 amino acid synthetic peptide that is a structural analog of human uroguanylin. Two large randomized, double-blind, placebo-controlled studies assessed the efficacy and safety of plecanatide in CIC patients (Rome III). Both doses of plecanatide, 3 mg and 6 mg resulted in a significantly greater percentage of patients who were durable overall complete spontaneous bowel movement (CSBM) responders (primary endpoint) compared with those who received placebo (plecanatide 3 mg, 21.0%; plecanatide 6 mg, 19.5%; placebo, 10.2%; p < 0.001 for each drug dose versus placebo). Plecanatide treatment also significantly reduced the severity of other CIC symptoms (straining effort, stool consistency, bloating). Also, plecanatide-treated patients reported high levels of satisfaction and improved QOL and desire to continue treatment. The rate of treatment-emergent adverse events with plecanatide was low, including rates of diarrhea (5%). Plecanatide is a luminally acting secretagogue that is efficacious and safe for the treatment of CIC. This article provides an overview of plecanatide in the management of adults with CIC.

Electrophysiological Mechanisms of Gastrointestinal Arrhythmogenesis: Lessons from the Heart

Disruptions in the orderly activation and recovery of electrical excitation traveling through the heart and the gastrointestinal (GI) tract can lead to arrhythmogenesis. For example, cardiac arrhythmias predispose to thromboembolic events resulting in cerebrovascular accidents and myocardial infarction, and to sudden cardiac death. By contrast, arrhythmias in the GI tract are usually not life-threatening and much less well characterized. However, they have been implicated in the pathogenesis of a number of GI motility disorders, including gastroparesis, dyspepsia, irritable bowel syndrome, mesenteric ischaemia, Hirschsprung disease, slow transit constipation, all of which are associated with significant morbidity. Both cardiac and gastrointestinal arrhythmias can broadly be divided into non-reentrant and reentrant activity. The aim of this paper is to compare and contrast the mechanisms underlying arrhythmogenesis in both systems to provide insight into the pathogenesis of GI motility disorders and potential molecular targets for future therapy.

Mechanisms of Electrical Activation and Conduction in the Gastrointestinal System: Lessons from Cardiac Electrophysiology

The gastrointestinal (GI) tract is an electrically excitable organ system containing multiple cell types, which coordinate electrical activity propagating through this tract. Disruption in its normal electrophysiology is observed in a number of GI motility disorders. However, this is not well characterized and the field of GI electrophysiology is much less developed compared to the cardiac field. The aim of this article is to use the established knowledge of cardiac electrophysiology to shed light on the mechanisms of electrical activation and propagation along the GI tract, and how abnormalities in these processes lead to motility disorders and suggest better treatment options based on this improved understanding. In the first part of the article, the ionic contributions to the generation of GI slow wave and the cardiac action potential (AP) are reviewed. Propagation of these electrical signals can be described by the core conductor theory in both systems. However, specifically for the GI tract, the following unique properties are observed: changes in slow wave frequency along its length, periods of quiescence, synchronization in short distances and desynchronization over long distances. These are best described by a coupled oscillator theory. Other differences include the diminished role of gap junctions in mediating this conduction in the GI tract compared to the heart. The electrophysiology of conditions such as gastroesophageal reflux disease and gastroparesis, and functional problems such as irritable bowel syndrome are discussed in detail, with reference to ion channel abnormalities and potential therapeutic targets. A deeper understanding of the molecular basis and physiological mechanisms underlying GI motility disorders will enable the development of better diagnostic and therapeutic tools and the advancement of this field.

Novel investigational drugs for constipation-predominant irritable bowel syndrome: a review

INTRODUCTION

Constipation-predominant irritable bowel syndrome (IBS-C) is a functional gastrointestinal (GI) disorder with an unknown etiology. A number of the drugs tested for IBS-C have also been applied to chronic constipation and chronic idiopathic constipation. Unfortunately, due to severe adverse effects, many drugs envisioned for IBS-C had been withdrawn from the market. Nevertheless, a number of potential new agents for this indication are now under development.

AREAS COVERED

The following review describes the most recently developed agents in preclinical as well as Phase 1 and Phase 2 clinical studies. Information was obtained from published literature, abstracts and the latest results found in Clinicaltrial.gov database. The authors put a special interest on glucagon-like peptide 1 analogue, bile acid modulators, serotonergic agents, guanylate cyclase C and cannabinoid antagonists.

EXPERT OPINION

To enter the market, a newly-developed drug has to meet several criteria, such as good bioavailability or the absence of drug-related adverse events. Taking into account constipation and abdominal pain as the main symptoms in IBS-C, a novel successful drug is usually able to improve both at the same time. Four out of fifteen investigational drugs described in this paper belong to the serotonergic family and have a good prognosis to reach the market; still, more long-term clinical studies are warranted.

Calea zacatechichi dichloromethane extract exhibits antidiarrheal and antinociceptive effects in mouse models mimicking irritable bowel syndrome

Calea zacatechichi Schltdl. (Asteraceae alt. Compositae) is a Mexican plant commonly used in folk medicine to treat respiratory and gastrointestinal (GI) disorders. The objective of this study is to characterize the effect of C. zacatechichi extracts in mouse models mimicking the symptoms of irritable bowel syndrome (IBS). Powdered C. zacatechichi herb (leaves, stems, and flowers) was extracted with methanol. Methanolic extract was filtered and evaporated giving methanolic fraction. The residue was extracted with dichloromethane (DCM). Methanolic and DCM (200 mg/kg, per os) extracts were screened for their effect on GI motility in several in vitro tests, and the antidiarrheal and antinociceptive effects were assessed using mouse models. The influence of the DCM extract on motoric parameters and exploratory behaviors was also assessed. Finally, the composition of C. zacatechichi DCM extract was qualitatively analyzed using liquid chromatography-mass spectrometry (LC-MS) method. C. zacatechichi DCM extract significantly inhibited the contractility of mouse colon in vitro (IC₅₀ = 17 ± 2 μg/ml). Administration of the DCM extract in vivo (200 mg/kg, per os) significantly prolonged the time of whole GI transit (46 ± 1 vs. 117 ± 27 min for control and DCM-treated animals, respectively; P = 0.0023), inhibited hypermotility, and reduced pain in mouse models mimicking functional GI disorders. Our findings suggest that constituents of the C. zacatechichi DCM extract exhibit antidiarrheal and analgesic activity. The extract may thus become an attractive material for isolation of compounds that may be used as a supplementary treatment for pain and diarrhea associated with IBS in the future.

Chronic constipation, irritable bowel syndrome with constipation and constipation with pain/discomfort: similarities and differences

OBJECTIVES

Some patients with chronic constipation (CC) have abdominal pain and discomfort (painful CC) without fulfilling the criteria for irritable bowel syndrome (IBS). Our aim was to investigate similarities and differences among nonpainful CC, painful CC, and CC in patients with IBS according to prevalence, individual symptoms, associated factors, and impact on health-related quality of life and use of medical resources.

METHODS

We conducted a telephone survey of a random sample of the Spanish population (N=1500). Bowel symptoms were recorded using the Rome III questionnaire, health-related quality of life using the short form-12 (SF-12) and quality of live in constipation-20 (CVE-20) questionnaires, and self-reported constipation, lifestyle habits, and consultation behavior using an ad hoc questionnaire.

RESULTS

The overall prevalence of CC was 19.2%, with prevalence by subgroups being 13.9% for nonpainful CC, 2.0% for painful CC, and 3.3% for CC in patients with IBS. CC was more prevalent among women at a ratio of 2.7:1. Subjects with painful CC and CC in patients with IBS were younger, reported more constipation, and had more symptoms than subjects with nonpainful CC. Age and physical activity were significantly associated with CC. Symptoms associated with consultation were abdominal pain and digitation. Nonpainful CC patients were more satisfied with laxative use than were the other subgroups. Subjects with CC showed a significant impairment in the physical and mental component of the SF-12 questionnaire.

CONCLUSIONS

CC appears to be a spectrum; most patients do not have abdominal pain/discomfort but others (with otherwise quite similar characteristics) are patients with IBS or are out of any established diagnosis.

Linaclotide

Each month, subscribers to The Formulary Monograph Service receive 5 to 6 well-documented monographs on drugs that are newly released or are in late phase 3 trials. The monographs are targeted to Pharmacy & Therapeutics Committees. Subscribers also receive monthly 1-page summary monographs on agents that are useful for agendas and pharmacy/nursing in-services. A comprehensive target drug utilization evaluation/medication use evaluation (DUE/MUE) is also provided each month. With a subscription, the monographs are sent in print and are also available on-line. Monographs can be customized to meet the needs of a facility. Subscribers to The Formulary Monograph Service also receive access to a pharmacy bulletin board, The Formulary Information Exchange (The F.I.X.). All topics pertinent to clinical and hospital pharmacy are discussed on The F.I.X. A drug class review is now published monthly with The Formulary Monograph Service. Through the cooperation of The Formulary, Hospital Pharmacy publishes selected reviews in this column. For more information about The Formulary Monograph Service or The F.I.X., call The Formulary at 800-322-4349. The February 2013 monograph topics are tofacitinib, cabozantinib, suvorexant, vortioxetine, and apremilast. The DUE/MUE is on tofacitinib.

Linaclotide

Each month, subscribers to The Formulary Monograph Service receive 5 to 6 well-documented monographs on drugs that are newly released or are in late phase 3 trials. The monographs are targeted to Pharmacy & Therapeutics Committees. Subscribers also receive monthly 1-page summary monographs on agents that are useful for agendas and pharmacy/nursing in-services. A comprehensive target drug utilization evaluation/medication use evaluation (DUE/MUE) is also provided each month. With a subscription, the monographs are sent in print and are also available on-line. Monographs can be customized to meet the needs of a facility. Subscribers to The Formulary Monograph Service also receive access to a pharmacy bulletin board, The Formulary Information Exchange (The F.I.X.). All topics pertinent to clinical and hospital pharmacy are discussed on The F.I.X. A drug class review is now published monthly with The Formulary Monograph Service. Through the cooperation of The Formulary, Hospital Pharmacy publishes selected reviews in this column. For more information about The Formulary Monograph Service or The F.I.X., call The Formulary at 800-322-4349. The February 2013 monograph topics are tofacitinib, cabozantinib, suvorexant, vortioxetine, and apremilast. The DUE/MUE is on tofacitinib.

Plecanatide, an oral guanylate cyclase C agonist acting locally in the gastrointestinal tract, is safe and well-tolerated in single doses

PURPOSE

Plecanatide, an analogue of uroguanylin, activates the guanylate cyclase C (GC-C) receptor found on the GI mucosal epithelial cells, leading to secretion of fluid, facilitating bowel movements. Plecanatide is being investigated as a potential treatment for constipating GI disorders. The aim of this investigation was to assess the safety, tolerability, pharmacokinetics (PK), and pharmacodynamics (PD) of single doses of plecanatide in healthy volunteers.

METHODS

A total of 72 healthy volunteers at a single site were randomized in 9 cohorts to receive oral plecanatide or placebo from 0.1 to 48.6 mg. Plasma PK samples were collected pre-dose and post-dose. PD assessments included time to first stool, stool frequency, and stool consistency using the Bristol Stool Form Scale. All adverse events were documented.

RESULTS

Plecanatide was safe and well-tolerated at all dose levels. A total of 17 of 71 subjects (23.9%) reported 25 treatment-emergent adverse events (TEAEs) during the study. The number of TEAEs reported by subjects who received plecanatide or placebo was comparable (24.5 vs. 22.2%, respectively). There were no dose-related increases in TEAEs or any SAEs reported. No measurable systemic absorption of oral plecanatide was observed at any of the oral doses studied, utilizing an assay sensitive down to 1 ng/mL.

CONCLUSIONS

Plecanatide, an oral GC-C agonist, acting locally within the GI tract without measurable systemic exposure, was safe and well-tolerated in single doses up to 48.6 mg. The study was not powered for statistical analyses, but trends in PD parameters supported continued clinical development.

[Psychopharmacological treatment in patients with somatoform disorders and functional body syndromes]

Somatoform disorders and functional body syndromes define a major, diagnostically heterogeneous group of patients with medically unexplained physical symptoms. Psychopharmacological approaches can be derived from the conceptualization of somatoform symptoms and syndromes within a biopsychosocial model. The survey presented focuses on randomized, double-blind and placebo-controlled studies. Antidepressants show a statistically and clinically relevant impact on many somatoform symptoms. In special reference to pain symptoms serotonergic and noradrenergic antidepressants seem to mediate a more favorable effect than selective serotonin reuptake inhibitors. For some functional body syndromes, e.g. irritable bowel syndrome and fibromyalgia, a major analgesic effect of antidepressants can be underlined as well. The empirical data for fibromyalgia, however, seem to be more convincing than for irritable bowel syndrome. Pregabalin holds an empirically well established position in the treatment of fibromyalgia. As yet there is no convincing psychopharmacological strategy for chronic fatigue syndrome. Probably due to the inherent relationships to anxiety, obsessive-compulsive and depressive disorders, both hypochondria and body dysmorphic disorder can be positively treated by serotonergic antidepressants as well.

Rifaximin for the treatment of irritable bowel syndrome

INTRODUCTION

Few therapeutic options are available for irritable bowel syndrome (IBS). Lubiprostone is approved by the FDA for IBS with constipation, and alosetron in IBS with diarrhea (IBS-D). It has been proposed that alterations in the bowel microflora may play a role in the pathophysiology of IBS, and that modulation of the microflora holds therapeutic potential. Rifaximin is a nonsystemic antibiotic that has shown efficacy in IBS.

AREAS COVERED

This narrative review covers the treatment options available for IBS-D and focuses on rifaximin. Rifaximin pharmacodynamics, clinical pharmacology and results of clinical studies from proof of concept to the latest Phase III and retreatment studies in IBS are summarized. Challenges to rifaximin use, safety issues and regulatory data are also discussed.

EXPERT OPINION

The evidence supports rifaximin as an emerging treatment for IBS. Strategies for appropriate patient selection need to be further developed, and continued efficacy of rifaximin over repeated treatment courses needs to be better characterized.