Lubiprostone for the treatment of adults with constipation and irritable bowel syndrome

Comparative Efficacy and Safety of Lubiprostone and Osmotic Laxatives in Chronic Idiopathic Constipation: A Systematic Review and Network Meta-Analysis

OBJECTIVE

The objective of this study is to compare the efficacy and safety of lubiprostone (Lub) with osmotic laxatives in the treatment of chronic idiopathic constipation (CIC).

METHODS

A comprehensive literature search was conducted using PubMed, EMBASE, and the Cochrane Library in May 2024. Studies that met the inclusion criteria were manually searched by two independent reviewers. The efficacy was assessed by the proportion of patients with spontaneous bowel movements (SBMs) within 24 h after the first administration of the medication and SBMs in Weeks 1 and 4. Safety was evaluated based on adverse events including nausea, diarrhea, and abdominal distension. Optimal probability values and the surface under the cumulative ranking area (SUCRA) were also calculated for all interventions. Higher SUCRA values indicate better efficacy and safety of the intervention.

RESULTS

Following a thorough search and screening process, 25 articles were included. Among the selected trials, 8 compared Lub to placebo, 10 compared polyethylene glycol (PEG) to placebo, 4 compared lactulose (Lac) to placebo, and 3 compared PEG to Lac. The meta-analysis results indicated that Lub and osmotic laxatives were significantly more effective than placebo. According to the SUCRA results, the highest rank probabilities were for Lub in increasing the SBMs and reducing abdominal distension.

CONCLUSION

Lubiprostone is more effective than PEG and Lactulose for treating CIC, with comparable safety profiles. However, this conclusion requires further validation through large-scale, high-quality studies.

Pharmacologic treatment of irritable bowel syndrome. Position statement of the Asociación Mexicana de Gastroenterología, 2024

INTRODUCTION

The aim of this position statement is to provide health professionals with an updated and evidence-based guideline for the pharmacologic management of irritable bowel syndrome (IBS) in Mexico.

MATERIAL AND METHODS

A literature review was conducted that included relevant guidelines and studies, up to the date of its publication. The mechanism of action, specific indications in IBS, safety profile, and availability of each therapeutic class were evaluated. The recommendations were developed by 14 experts, considering the clinical reality of IBS patients in Mexico.

RESULTS

Specific recommendations were issued for each class. Antispasmodics (alone or combined) are used as first-line therapy for pain management, whereas antidiarrheals, such as loperamide, are used for reducing diarrhea in diarrhea-predominant IBS (IBS-D) and laxatives are used for constipation in constipation-predominant IBS (IBS-C). 5-HT4 agonists (prucalopride and mosapride) are recommended in IBS-C and 5-HT3 antagonists (ondansetron) are recommended in IBS-D. Linaclotide is the only secretagogue available in Mexico and is used in IBS-C. Rifaximin-alpha stands out for its efficacy in a subgroup of patients with IBS-D or mixed IBS. Probiotics are conditionally recommended as adjuvant therapy due to heterogeneous evidence. Neuromodulators (tricyclic antidepressants, selective serotonin reuptake inhibitors, etc.) are recommended as second-line treatment for pain management. Mesalazine can be used in IBS-D, but the corresponding evidence is weak.

CONCLUSION

Overall, these recommendations provide a solid framework for personalizing treatment, based on the clinical characteristics of the Mexican patient with IBS.

Efficacy and safety of lubiprostone for the treatment of chronic idiopathic constipation: A phase 3, randomized, placebo-controlled study

INTRODUCTION

Chronic idiopathic constipation (CIC) negatively impacts quality of life and increases healthcare costs. Lubiprostone stimulates the secretion of intestinal fluid, in turn facilitating the passage of stools and alleviating associated symptoms. Lubiprostone has been available in Mexico since 2018, but its clinical efficacy has not been studied in a Mexican population.

AIM

To evaluate the efficacy of lubiprostone, assessed by changes in spontaneous bowel movement (SBM) frequency after one week of treatment with 24 μg oral lubiprostone (b.i.d.), as well as its safety, over four weeks of treatment.

STUDY

Randomized, double-blind, placebo-controlled study on 211 adults with CIC in Mexico.

RESULTS

The increase in SBM frequency, after one week of treatment, was significantly higher in the lubiprostone group than in the placebo group (mean: 4.9 [SD: 4.45] vs. 3.0 [3.14], p = 0.020). Secondary efficacy endpoints revealed a significantly higher proportion of SBM frequency/week in the lubiprostone group at weeks 2, 3, and 4. There was a better response within 24 h after the first dose with lubiprostone vs. placebo (60.0% vs. 41.5%; OR: 2.08, CI95%: [1.19, 3.62], p = 0.009) and the lubiprostone group also had significant improvement, with respect to straining, stool consistency, abdominal bloating, and Satisfaction Index. The main adverse events were gastrointestinal disorders in 13 (12.4%) lubiprostone-treated subjects and 4 (3.8%) control subjects.

CONCLUSIONS

Our data confirm the efficacy and safety of lubiprostone for the treatment of CIC in a Mexican population. Lubiprostone treatment induces relief from the most bothersome symptoms associated with constipation.

The ClC-2 Chloride Channel Activator, Lubiprostone, Improves Intestinal Barrier Function in Biopsies from Crohn’s Disease but Not Ulcerative Colitis Patients

The prostone analog, lubiprostone, is approved to manage constipation-predominant irritable bowel syndrome. Lubiprostone also protects intestinal mucosal barrier function in animal models of colitis. The aim of this study was to determine if lubiprostone improves barrier properties in isolated colonic biopsies from Crohn’s disease (CD) and ulcerative colitis (UC) patients. Sigmoid colon biopsies from healthy subjects, CD and UC patients in remission, and CD patients with active disease were mounted in Ussing chambers. Tissues were treated with lubiprostone or vehicle to determine the effects on transepithelial electrical resistance (TER), FITC-dextran 4kD (FD4) permeability, and electrogenic ion transport responses to forskolin and carbachol. Localization of the tight junction protein, occludin, was determined by immunofluorescence. Lubiprostone significantly increased ion transport across control, CD and UC remission biopsies but not active CD. Lubiprostone selectively improved TER in both CD remission and active disease biopsies but not in control or UC biopsies. The improved TER was associated with increased membrane localization of occludin. Lubiprostone selectively improved barrier properties of biopsies from CD patients vs. UC and independent of an ion transport response. These data indicate that lubiprostone has potential efficacy in improving mucosal integrity in Crohn’s disease.

Review of the Safety Profiles of Laxatives in Pregnant Women

Chronic constipation is one of the most common complaints seen in the gastroenterology clinic and is particularly prevalent in women. Women who become pregnant may suffer from existing constipation or develop constipation de novo. A thorough understanding of the safety of laxative therapies during pregnancy and the postpartum period is essential to successfully treating these women. Current understanding of the safety of both over the counter and prescription laxatives has not been adequately evaluated. In this article we provide an updated and comprehensive review of the safety profiles of laxatives that are currently used for the treatment of chronic constipation to aid the clinician in risk-benefit discussions with women who are currently or planning to become pregnant.

Chronic Constipation: Gastroenterohepatologist's Approach

BACKGROUND

Constipation is a common problem in gastroenterological practice. The prevalence of constipation is about 16%. Constipation can be primary or secondary.

SUMMARY

The diagnostic and therapeutic approach to patients with constipation begins with a detailed history and physical examination. In selected cases, the use of additional diagnostic procedures is very important. This includes the use of laboratory, endoscopic, and radiological examinations, as well as advanced physiological testing (anorectal manometry, balloon expulsion test, colonic transit studies, and defecography). Constipation therapy can be both nonoperative and operative. Nonoperative therapy includes the application of a lifestyle measures, pharmacotherapy and biofeedback therapy. Key Messages: Two key things when taking a medical history and physical examination are to rule out the existence of alarm symptoms/signs and to rule out secondary constipation (primarily drug-induced). Therapy begins with lifestyle modification, and in case of failure, bulk or osmotic laxatives are used. In case of failure, the use of lubiprostone is indicated, as well as linaclotide. Surgical treatment of constipation is reserved for cases of refractory constipation, with delayed intestinal transit.

Effects of the vibrating capsule on colonic circadian rhythm and bowel symptoms in chronic idiopathic constipation

BACKGROUND

Constipated patients remain dissatisfied with current treatments suggesting a need for alternative therapies.

AIM

Evaluate the mechanistic effects of oral vibrating capsule in chronic idiopathic constipation (CIC) by examining the temporal relationships between the onset of vibrations, complete spontaneous bowel movements (CSBM), and circadian rhythm.

METHODS

In post hoc analyses of two double-blind studies, CIC patients (Rome III) were randomized to receive 5 active or sham capsules/week for 8 weeks. The capsules were programmed for single vibration (study 1) or two vibration sessions with two modes, 8 hours apart (study 2). Daily electronic diaries assessed stool habit and percentage of CSBMs associated with vibrations. Responders were patients with ≥ 1 CSBM per week over baseline.

RESULTS

250 patients were enrolled (active = 133, sham = 117). During and within 3 hours of vibration, there were significantly more % CSBMs in the active vs. sham group (50% vs. 42%; P = .0018). In study 2, there were two CSBM peaks associated with vibration sessions. Significantly more % CSBMs occurred in active mode 1 (21.5%) vs. sham (11.5%); (P = .0357). Responder rates did not differ in study 1 (active vs. sham: 26.9% vs. 35.9%, P = .19) or study 2 (mode 1 vs. sham: 50% vs. 31.8%, P = .24; mode 2 vs. sham: 38.1% vs. 31.8%, P = .75). Device was well-tolerated barring mild vibration sensation.

CONCLUSIONS

Vibrating capsule may increase CSBMs possibly by enhancing the physiologic effects of waking and meals, and augmenting circadian rhythm, although responder rate was not different from sham. Two vibration sessions were associated with more CSBMs.

Treating Chronic Abdominal Pain in Patients with Chronic Abdominal Pain and/or Irritable Bowel Syndrome

Irritable bowel syndrome (IBS) is probably the most common diagnosis in gastroenterology involving the brain-gut axis. By definition, pain is the most frequent symptom experienced by patients. It is important to understand the biopsychosocial and physiologic aspects of the disease when discussing treatment of IBS. Such therapies as lifestyle modifications, changes in diet, and cognitive behavioral therapy should be used in conjunction with pharmacotherapy rather than pharmacotherapy alone. The pathophysiologic mechanisms are reviewed in this article along with the current treatments available, in the era of growing demand for more effective treatments for the pain component of IBS.

Chronic Constipation

Constipation is a common symptom that may be primary (idiopathic or functional) or associated with a number of disorders or medications. Although most constipation is self-managed by patients, 22% seek health care, mostly to primary care physicians (>50%) and gastroenterologists (14%), resulting in large expenditures for diagnostic testing and treatments. There is strong evidence that stimulant and osmotic laxatives, intestinal secretagogues, and peripherally restricted μ-opiate antagonists are effective and safe; the lattermost drugs are a major advance for managing opioid-induced constipation. Constipation that is refractory to available laxatives should be evaluated for defecatory disorders and slow-transit constipation using studies of anorectal function and colonic transit. Defecatory disorders are often responsive to biofeedback therapies, whereas slow-transit constipation may require surgical intervention in selected patients. Both efficacy and cost should guide the choice of treatment for functional constipation and opiate-induced constipation. Currently, no studies have compared inexpensive laxatives with newer drugs that work by other mechanisms.

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.

Opioid-Related Constipation in Patients With Non-cancer Pain Syndromes: a Review of Evidence-Based Therapies and Justification for a Change in Nomenclature

PURPOSE OF REVIEW

Opioids are a mainstay in the treatment of chronic non-cancer pain syndromes, but their analgesic benefits come at a cost as opioid-related constipation occurs in 40-80% of individuals taking chronic opioids. Furthermore, as 10-20% of the population suffers from constipation at baseline, it should be expected that while a proportion of individuals will develop constipation as a direct consequence of opioids (OIC), others will experience it as an exacerbation of their baseline constipation (OEC). Herein, we review the evidence-based data for treatments directed at opioid-related constipation focusing on individuals with non-cancer pain syndromes and provide a template for the development of differentiated treatment algorithms for OIC and OEC.

RECENT FINDINGS

Historical and current treatment protocols recommend traditional laxatives, but these are ineffective in up to 50%, due in part to the heterogeneous pathogenesis of constipation. Therapeutic decisions must be tailored to account for this overlapping pathogenesis. OIC and OEC are distinct entities. As such, additional research and guidelines should address these as different patient populations.

Chemotherapy-Induced Constipation and Diarrhea: Pathophysiology, Current and Emerging Treatments

Gastrointestinal (GI) side-effects of chemotherapy are a debilitating and often overlooked clinical hurdle in cancer management. Chemotherapy-induced constipation (CIC) and Diarrhea (CID) present a constant challenge in the efficient and tolerable treatment of cancer and are amongst the primary contributors to dose reductions, delays and cessation of treatment. Although prevalence of CIC is hard to estimate, it is believed to affect approximately 16% of cancer patients, whilst incidence of CID has been estimated to be as high as 80%. Despite this, the underlying mechanisms of both CID and CIC remain unclear, but are believed to result from a combination of intersecting mechanisms including inflammation, secretory dysfunctions, GI dysmotility and alterations in GI innervation. Current treatments for CIC and CID aim to reduce the severity of symptoms rather than combating the pathophysiological mechanisms of dysfunction, and often result in worsening of already chronic GI symptoms or trigger the onset of a plethora of other side-effects including respiratory depression, uneven heartbeat, seizures, and neurotoxicity. Emerging treatments including those targeting the enteric nervous system present promising avenues to alleviate CID and CIC. Identification of potential targets for novel therapies to alleviate chemotherapy-induced toxicity is essential to improve clinical outcomes and quality of life amongst cancer sufferers.

New Options in Constipation Management

Constipation is common in the general population and for those on opioids and/or who are suffering from advanced cancer. Self-management consists of dietary changes, exercise, and laxatives. However, responses to self-management efforts are often inadequate to relieve the subjective and objective experience of constipation. Multiple new anti-constipating medications have recently been tested in randomized trials and the following are available commercially: probiotics, prucalopride, lubiprostone, linaclotide, elobixibat, antidepressants, methylnaltrexone, alvimopan, and naloxegol. This review will discuss the evidence-based benefits of these medications and outline an approach to managing constipation.

NSAID-induced small intestinal damage--roles of various pathogenic factors

BACKGROUND/AIMS

NSAID-induced enteropathy has been the focus of recent basic and clinical research subsequent to the development of the capsule endoscope and double-balloon endoscope. We review the possible pathogenic mechanisms underlying NSAID-induced enteropathy and discuss the role of the inhibition of COX-1/COX-2 and the influences of food as well as various prophylactic treatments on these lesions.

METHODS

Studies were performed in experimental animals.

RESULTS

Multiple factors, such as intestinal hypermotility, decreased mucus secretion, enterobacteria, and upregulation of iNOS/NO expression, are involved in the pathogenesis of NSAID-induced enteropathy, in addition to the decreased production of PGs due to the inhibition of COX. Enterobacterial invasion is the most important pathogenic event, and intestinal hypermotility, which was associated with this event, is essential for the development of these lesions. NSAIDs also upregulate the expression of COX-2, and the inhibition of both COX-1 and COX-2 is required for the intestinal ulcerogenic properties of NSAIDs to manifest. NSAID-induced enteropathy is prevented by PGE2, atropine, ampicillin, and aminoguanidine as well as soluble dietary fiber, and exacerbated by antisecretory drugs such as proton pump inhibitors.

CONCLUSION

These findings on the pathogenesis of NSAID-induced enteropathy will be useful for the future development of intestinal-sparing alternatives to standard NSAIDs.

ClC-2 regulation of intestinal barrier function: Translation of basic science to therapeutic target

The ClC-2 chloride channel is a member of the voltage-gated chloride channel family. ClC-2 is involved in various physiological processes, including fluid transport and secretion, regulation of cell volume and pH, maintaining the membrane potential of the cell, cell-to-cell communication, and tissue homeostasis. Recently, our laboratory has accumulated evidence indicating a critical role of ClC-2 in the regulation of intestinal barrier function by altering inter-epithelial tight junction composition. This review will detail the role of ClC-2 in intestinal barrier function during intestinal disorders, including experimental ischemia/reperfusion injury and dextran sodium sulfate (DSS)-induced inflammatory bowel disease. Details of pharmacological manipulation of ClC-2 via prostone agonists will also be provided in an effort to show the potential therapeutic relevance of ClC-2 regulation, particularly during intestinal barrier disruption.

Resting anal pressure, not outlet obstruction or transit, predicts healthcare utilization in chronic constipation: a retrospective cohort analysis

BACKGROUND

Chronic constipation is common and exerts a considerable burden on health-related quality of life and healthcare resource utilization. Anorectal manometry (ARM) and colonic transit testing have allowed classification of subtypes of constipation, raising promise of targeted treatments. There has been limited study of the correlation between physiological parameters and healthcare utilization.

METHODS

All patients undergoing ARM and colonic transit testing for chronic constipation at two tertiary care centers from 2000 to 2014 were included in this retrospective study. Our primary outcomes included number of constipation-related and gastroenterology visits per year. Multivariate linear regression adjusting for confounders defined independent effect of measures of colonic and anorectal function on healthcare utilization.

KEY RESULTS

Our study included 612 patients with chronic constipation. More than 50% (n = 333) of patients had outlet obstruction by means of balloon expulsion testing and 43.5% (n = 266) had slow colonic transit. On unadjusted analysis, outlet obstruction (1.98 vs 1.68), slow transit (2.40 vs 2.07) and high resting anal pressure (2.16 vs 1.76) were all associated with greater constipation-related visits/year compared to patients without each of those parameters (p < 0.05 for all). Outlet obstruction and high resting anal pressure were also associated with greater number of gastroenterology visits/year. After multivariate adjustment, high resting anal pressure was the only independent predictor of increased constipation-related visits/year (p = 0.02) and gastroenterology visits/year (p = 0.04).

CONCLUSIONS & INFERENCES

Among patients with chronic constipation, high resting anal pressure, rather than outlet obstruction or slow transit, predicts healthcare resource utilization.

A comparison of linaclotide and lubiprostone dosing regimens on ion transport responses in human colonic mucosa

Linaclotide, a synthetic guanylyl cyclase C (GC-C) agonist, and the prostone analog, Lubiprostone, are approved to manage chronic idiopathic constipation and constipation-predominant irritable bowel syndrome. Lubiprostone also protects intestinal mucosal barrier function in ischemia. GC-C signaling regulates local fluid balance and other components of intestinal mucosal homeostasis including epithelial barrier function. The aim of this study was to compare if select dosing regimens differentially affect linaclotide and lubiprostone modulation of ion transport and barrier properties of normal human colonic mucosa. Normal sigmoid colon biopsies from healthy subjects were mounted in Ussing chambers. Tissues were treated with linaclotide, lubiprostone, or vehicle to determine effects on short-circuit current (I_sc). Subsequent I_sc responses to the cAMP agonist, forskolin, and the calcium agonist, carbachol, were also measured to assess if either drug caused desensitization. Barrier properties were assessed by measuring transepithelial electrical resistance. I_sc responses to linaclotide and lubiprostone were significantly higher than vehicle control when administered bilaterally or to the mucosal side only. Single versus cumulative concentrations of linaclotide showed differences in efficacy while cumulative but not single dosing caused desensitization to forskolin. Lubiprostone reduced forskolin responses under all conditions. Linaclotide and lubiprostone exerted a positive effect on TER that was dependent on the dosing regimen. Linaclotide and lubiprostone increase ion transport responses across normal human colon but linaclotide displays increased sensitivity to the dosing regimen used. These findings may have implications for dosing protocols of these agents in patients with constipation.

Lubiprostone vs Senna in postoperative orthopedic surgery patients with opioid-induced constipation: A double-blind, active-comparator trial

AIM: To investigate the efficacy of lubiprostone compared to Senna on bowel symptoms and constipation in post-operative orthopedic patients treated with opioids.

METHODS: In this double blind, randomized, active comparator trial, adults who required opioids for analgesia following orthopedic procedures and who were admitted in inpatient rehabilitation were randomized following baseline assessments to lubiprostone (Amitza^®), orally twice a day or Senna (generic) two capsules administered daily for six days. Subjects were assessed using the patient assessment of constipation (PAC)-symptoms (PAC-SYM) and the PAC-quality of life (PAC-QOL) scales measured at baseline and Day 7; Subjects were assessed daily for secondary measures included the Bristol stool scale bowel consistency, specific bowel symptom score (Nausea, cramping, straining, completeness, abdominal pain, time per lavatory attempt, assistance needed), adverse events and rescue medications required. Function was measured using the functional independence measure (FIM) at admission and discharge; length of stay (LOS) and missed treatments due to gastrointestinal symptoms were also assessed.

RESULTS: 64 adults were enrolled; 56 participants (28 in each group) had baseline and follow up measures and were included in the intention to treat (ITT) analyses. 43 participants completed the study, 21 in the active lubiprostone and 22 in the active Senna group. The mean age of the participants was 71.5 years (SD = 11.4 years, range: 28-96 years). In the ITT analyses, participants showed significant improvement in bowel symptoms as measured by the PAC-SYM (mean ± SD, -0.28 ± 0.60, range: -1-2.33) and PAC-QOL (mean ± SD, 0.33 ± 0.81, range: -1.5-2.0) over time, but there were no significant differences between the lubiprostone and Senna groups in mean change in the PAC-SYM (-0.20 ± 0.60 vs -0.36 ± 0.61, P = 0.61 respectively) or the PAC-QOL (0.29 ± 0.76 vs 0.37 ± 0.87, P = 0.61 respectively). The mean change in each bowel symptom also did not significantly differ between treatment groups on ITT analyses, except for completeness of bowel movement, with the Senna group showing greater negative mean change in bowel movement completeness (-0.56 ± 1.01 vs -2.00 ± 1.41, P = 0.03) and for reduction of abdominal pain, favoring Senna (-0.14 ± 0.73 vs -0.73 ± 1.08, P = 0.04). Fifteen (75%) participants in the lubiprostone and in the Senna group requested rescue treatments. Participants made significant functional improvement from admission to discharge over a median LOS of 12 d, with a mean FIM change of 29.13 ± 13.58 and no significant between group differences (27.0 ± 9.2 vs 31.5 ± 16.6, P = 0.27).

CONCLUSION: Both lubiprostone and Senna improved constipation-related symptoms and QOL in opioid-induced constipation, with no significant between-group differences.

Effects of lubiprostone on pacemaker activity of interstitial cells of cajal from the mouse colon

Lubiprostone is a chloride (Cl^-) channel activator derived from prostaglandin E₁ and used for managing constipation. In addition, lubiprostone affects the activity of gastrointestinal smooth muscles. Interstitial cells of Cajal (ICCs) are pacemaker cells that generate slow-wave activity in smooth muscles. We studied the effects of lubiprostone on the pacemaker potentials of colonic ICCs. We used the whole-cell patch-clamp technique to determine the pacemaker activity in cultured colonic ICCs obtained from mice. Lubiprostone hyperpolarized the membrane and inhibited the generation of pacemaker potentials. Prostanoid EP₁, EP₂, EP₃, and EP₄ antagonists (SC-19220, PF-04418948, 6-methoxypyridine-2-boronc acid N-phenyldiethanolamine ester, and GW627368, respectively) did not block the response to lubiprostone. _L-NG-nitroarginine methyl ester (_L-NAME, an inhibitor of nitric oxide synthase) and 1H-[1,2,4]oxadiazolo[4,3,-a]quinoxalin-1-one (ODQ, an inhibitor of guanylate cyclase) did not block the response to lubiprostone. In addition, tetraethylammonium (TEA, a voltage-dependent potassium [K⁺] channel blocker) and apamin (a calcium [Ca²⁺]-dependent K⁺ channel blocker) did not block the response to lubiprostone. However, glibenclamide (an ATP-sensitive K⁺ channel blocker) blocked the response to lubiprostone. Similar to lubiprostone, pinacidil (an opener of ATP-sensitive K⁺ channel) hyperpolarized the membrane and inhibited the generation of pacemaker potentials, and these effects were inhibited by glibenclamide. These results suggest that lubiprostone can modulate the pacemaker potentials of colonic ICCs via activation of ATP-sensitive K⁺ channel through a prostanoid EP receptor-independent mechanism.

Constipation-predominant irritable bowel syndrome: a review of current and emerging drug therapies

Irritable bowel syndrome (IBS) is a highly prevalent medical condition that adversely affects patient quality of life and constitutes a significant economic burden on healthcare resources. A large proportion of patients suffer from the constipation subtype of IBS (IBS-C), most commonly afflicting older individuals and those with a lower socioeconomic status. Conventional pharmacologic and nonpharmacologic treatment options have limited efficacies and/or significant adverse events, which lead to increased long-term health care expenditures. Failure to effectively treat IBS-C patients over the past decades has largely been due to a poor understanding of disease pathophysiology, lack of a global view of the patient, and an inappropriate selection of patients and treatment endpoints in clinical trials. In recent years, however, more effective and safer drugs have been developed for the treatment of IBS-C. The advancement in the area of pharmacologic treatment is based on new knowledge of the pathophysiologic basis of IBS-C and the development of drugs with increased selectivity within pharmacologic classes with recognized efficacies. This narrative review covers the spectrum of available drugs and their mechanisms of action, as well as the efficacy and safety profiles of each as determined in relevant clinical trials that have investigated treatment options for IBS-C and chronic constipation. A brief summary of laxative-based treatment options is presented, followed by up-to-date assessments for three classes of drugs: prokinetics, prosecretory agents, and bile acid modulators.

Elobixibat and its potential role in chronic idiopathic constipation

Chronic idiopathic constipation is highly prevalent among adults. Bile acids (BAs) and the enterohepatic BA circulation modulate colonic secretion and motility that affect transit. BAs in the colon have a dual action as osmotic and stimulant agents. Newer agents, such as elobixibat (A3309), an inhibitor of the ileal BA transporter, have the potential to improve significantly the management of chronic constipation, with minimal adverse effects. Elobixibat modulates the enterohepatic BA circulation, enhancing the delivery of BAs to the colon where they induce secretory and motor effects. Secondary effects of the inhibition of BA absorption are reduced activation of the farnesoid X receptor, decreased secretion of fibroblast growth factor-19 into the portal circulation, and increased BA synthesis. This review focuses on the role of BAs, the enterohepatic BA circulation, and an ileal BA transporter inhibitor (elobixibat) in chronic constipation.

Lubiprostone prevents nonsteroidal anti-inflammatory drug-induced small intestinal damage by suppressing the expression of inflammatory mediators via EP4 receptors

Lubiprostone, a bicyclic fatty acid derived from prostaglandin E1, has been used to treat chronic constipation and irritable bowel syndrome, and its mechanism of action has been attributed to the stimulation of intestinal fluid secretion via the activation of the chloride channel protein 2/cystic fibrosis transmembrane regulator (ClC-2/CFTR) chloride channels. We examined the effects of lubiprostone on indomethacin-induced enteropathy and investigated the functional mechanisms involved, including its relationship with the EP4 receptor subtype. Male Sprague-Dawley rats were administered indomethacin (10 mg/kg p.o.) and killed 24 hours later to examine the hemorrhagic lesions that developed in the small intestine. Lubiprostone (0.01-1 mg/kg) was administered orally twice 30 minutes before and 9 h after the indomethacin treatment. Indomethacin markedly damaged the small intestine, accompanied by intestinal hypermotility, a decrease in mucus and fluid secretion, and an increase in enterobacterial invasion as well as the up-regulation of inducible nitric-oxide synthase (iNOS) and tumor necrosis factor α (TNFα) mRNAs. Lubiprostone significantly reduced the severity of these lesions, with the concomitant suppression of the functional changes. The effects of lubiprostone on the intestinal lesions and functional alterations were significantly abrogated by the coadministration of AE3-208 [4-(4-cyano-2-(2-(4-fluoronaphthalen-1-yl)propionylamino)phenyl)butyric acid], a selective EP4 antagonist, but not by CFTR(inh)-172, a CFTR inhibitor. These results suggest that lubiprostone may prevent indomethacin-induced enteropathy via an EP4 receptor-dependent mechanism. This effect may be functionally associated with the inhibition of intestinal hypermotility and increase in mucus/fluid secretion, resulting in the suppression of bacterial invasion and iNOS/TNFα expression, which are major pathogenic events in enteropathy. The direct activation of CFTR/ClC-2 chloride channels is not likely to have contributed to the protective effects of lubiprostone.

Irritable bowel syndrome: The evolution of multi-dimensional looking and multidisciplinary treatments

Irritable bowel syndrome (IBS) is common in the society. Among the putative pathogeneses, gut dysmotility results in pain and disturbed defecation. The latter is probably caused by the effect of abnormal gut water secretion. The interaction between abnormal gas accumulation, abdominal pain and bloating remains controversial. Visceral hypersensitivity and its modification along with the central transmission are the characteristics of IBS patients. The identification of biologic markers based on genetic polymorphisms is undetermined. Imbalanced gut microbiota may alter epithelial permeability to activate nociceptive sensory pathways which in turn lead to IBS. Certain food constituents may exacerbate bowel symptoms. The impact of adult and childhood abuses on IBS is underestimated. Using the concept of biopsychosocial dysfunction can integrate multidimensional pathogeneses. Antispasmodics plus stool consistency modifiers to treat the major symptoms and defecation are the first-line drug treatment. New drugs targeting receptors governing bowel motility, sensation and secretion can be considered, but clinicians must be aware of their potential serious side effects. Psychiatric drugs and modalities may be the final options for treating intractable subjects. Probiotics of multi-species preparations are safe and worth to be considered for the treatment. Antibiotics are promising but their long-term safety and effectiveness are unknown. Diet therapy including exclusion of certain food constituents is an economic measure. Using relatively safe complementary and alternative medicines (CAMs) may be optional to those patients who failed classical treatment. In conclusion, IBS is a heterogeneous disorder with multidimensional pathogeneses. Personalized medicines with multidisciplinary approaches using different classes of drugs, psychiatric measures, probiotics and antibiotics, dietary therapy, and finally CAMs, can be considered.

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.

Constella™(EU)-Linzess™(USA): the last milestone in the long journey of the peptide linaclotide and its implications for the future of peptide drugs

Irritable bowel syndrome with constipation (IBS-C) and chronic idiopathic constipation (CIC) are highly prevalent gastrointestinal disorders associated with health, economical and social problems. Recently, after a long journey of preclinical studies and clinical trials, linaclotide, a first-in-class GC-C receptor peptide agonist, has received the approval in the USA and Europe for the treatment of IBS-C and CIC. This article provides an overview of clinical, economic and biological aspects of IBS-C and CIC and covers the current and emerging therapeutic agents for treating these conditions. Particularly, the pharmacodynamic and pharmacokinetic properties of linaclotide, a small, disulfide-rich peptide, and its implications in the future of peptide drug discovery and development are discussed.

The cannabinoid-1 receptor inverse agonist taranabant reduces abdominal pain and increases intestinal transit in mice

BACKGROUND

Constipation-predominant irritable bowel syndrome (IBS-C) is a common functional gastrointestinal (GI) disorder with abdominal pain and decreased motility. Current treatments of IBS-C are insufficient. The aim of this study was to evaluate the potential application of taranabant, a cannabinoid type 1 (CB1) inverse agonist using mouse models mimicking the symptoms of IBS-C.

METHODS

Changes in intestinal contractile activity were studied in vitro, using isolated mouse ileum and colon and intracellular recordings. In vivo, whole gastrointestinal transit (WGT) and fecal pellet output (FPO) were measured under standard conditions and with pharmacologically delayed GI transit. The antinociceptive effect was evaluated in mustard oil- and acetic acid-induced models of visceral pain. Forced swimming and tail suspension tests were performed and locomotor activity was measured to evaluate potential central side effects.

KEY RESULTS

In vitro, taranabant (10(-10) -10(-7) mol L(-1)) increased contractile responses in mouse ileum and blocked the effect of the CB agonist WIN 55,212-2. Taranabant had no effect on the amplitude of electrical field stimulation (EFS)-evoked junction potentials. In vivo, taranabant (0.1-3 mg kg(-1), i.p. and 3 mg kg(-1), p.o.) increased WGT and FPO in mice and reversed experimental constipation. The effect of taranabant was absent in CB1(-/-) mice. Taranabant significantly decreased the number of pain-related behaviors in animal models. At the doses tested, taranabant did not display mood-related adverse side effects typical for CB1 receptor inverse agonists.

CONCLUSIONS & INFERENCES

Taranabant improved symptoms related to slow GI motility and abdominal pain and may become an attractive template in the development of novel therapeutics targeting IBS-C.

Drug development for the irritable bowel syndrome: current challenges and future perspectives

Medications are frequently used for the treatment of patients with the irritable bowel syndrome (IBS), although their actual benefit is often debated. In fact, the recent progress in our understanding of the pathophysiology of IBS, accompanied by a large number of preclinical and clinical studies of new drugs, has not been matched by a significant improvement of the armamentarium of medications available to treat IBS. The aim of this review is to outline the current challenges in drug development for IBS, taking advantage of what we have learnt through the Rome process (Rome I, Rome II, and Rome III). The key questions that will be addressed are: (a) do we still believe in the "magic bullet," i.e., a very selective drug displaying a single receptor mechanism capable of controlling IBS symptoms? (b) IBS is a "functional disorder" where complex neuroimmune and brain-gut interactions occur and minimal inflammation is often documented: do we need to target gut motility, visceral sensitivity, or minimal inflammation? (c) are there validated biomarkers (accepted by regulatory agencies) for studies of sensation and motility with experimental medications in humans? (d) do animal models have predictive and translational value? (e) in the era of personalized medicine, does pharmacogenomics applied to these medications already play a role? Finally, this review will briefly outline medications currently used or in development for IBS. It is anticipated that a more focused interaction between basic science investigators, pharmacologists, and clinicians will lead to better treatment of IBS.

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

INTRODUCTION

The high prevalence of irritable bowel syndrome (IBS), a chronic gastrointestinal (GI) disorder, its lack of satisfactory effective drugs and its complicated pathophysiology lead to the demand of new therapeutic agents. During a new drug development process, the pharmacokinetic profiling is of a great considerable importance comparable to drug's efficacy. This involves the drug's absorption, distribution, metabolism and excretion, all of which are crucial to its usefulness. In addition, the toxicological profile and possible adverse reactions of the drug should be identified. Also its interactions should be identified at different phases of trials. Several pharmacokinetic studies are carried out to achieve drugs with the best absorption and bioavailability and the least adverse effects and lowest toxicity.

AREAS COVERED

To make an update on new clinically introduced drugs for IBS and their dynamics and kinetics data, the present systematic review was accomplished. All relevant bibliographic databases were searched from the year 2003 up to May 2012 to identify all clinical trials that evaluated the potential efficacy of a novel agent in IBS.

EXPERT OPINION

Some evaluated drugs, such as ramosetron (5-HT3 antagonist) and pexacerfont (CRF1 receptor antagonist), have shown some benefits in diarrhea-predominant IBS (D-IBS), while, prucalopride and mosapride (5-HT4 agonist) with prokinetic effect were found useful in constipation-predominant IBS (C-IBS). Besides, dexloxiglumide, lubiprostone and linaclotide have shown beneficial effects in C-IBS patients. Melatonin regulates GI tract motility and, asimadoline, gabapentin and pregabalin show reduction of pain threshold and visceral hypersensitivity. Glucagon-like peptide analog, calcium-channel blockers and neurokinin receptor antagonists have shown benefits in pain attacks. More time is required to indicate both efficacy and safety in long-term treatment due to multifactorial pathophysiology, variations in individual responses and insufficient assessment methods, which limit the right decision-making process about the efficacy and tolerability of these new drugs.

Irritable bowel syndrome with constipation: a European-focused systematic literature review of disease burden

OBJECTIVE

To conduct a systematic literature review to assess burden of disease and unmet medical needs in patients with irritable bowel syndrome (IBS) with constipation (IBS-C), with a focus on five European countries (France, Germany, Italy, Spain, UK).

METHODS

MEDLINE, EMBASE, and grey literature searches were carried out using terms for IBS and constipation, to identify studies reporting epidemiological, clinical, humanistic, or economic outcomes for IBS-C, published between 2000 and 2010.

RESULTS

Searches identified 885 unique abstracts and 33 supplementary articles, of which 100 publications and six grey literature sources met the inclusion criteria. Among patients with IBS, the prevalence estimates of IBS-C ranged from 1 to 44%. Co-morbid conditions, such as personality traits, psychological distress, and stress, were common. Patients with IBS-C had lower health-related quality-of-life (HRQoL) compared with the general population, and clinical trials suggested that effectively treating IBS-C improves HRQoL. The European societal cost of IBS-C is largely unknown, as no IBS-C-specific European cost-of-illness studies were identified. Two cost analyses demonstrated the substantial societal impact of IBS-C, including reduced productivity at work and work absenteeism. Guidelines offered similar recommendations for the diagnosis and management of IBS; however, recommendations specifically for IBS-C varied by country. Current IBS-C treatment options have limited efficacy and the risk:benefit profile of early 5-HT(4) agonists restricts clinical use.

CONCLUSIONS

This systematic review indicates a clear need for European-focused IBS-C burden-of-disease and cost-of-illness studies to address identified evidence gaps. There is a need for new therapies for IBS-C that are effective, well tolerated, and have a positive impact on HRQoL.

Safety evaluation of lubiprostone in the treatment of constipation and irritable bowel syndrome

INTRODUCTION

Lubiprostone is approved in the United States for the treatment of chronic idiopathic constipation and constipation predominant irritable bowel syndrome (IBS-C). Lubiprostone causes secretion of fluid and electrolytes in the small bowel, through the activation of chloride channels, and thereby induces laxation and improvement of bowel functions. It is generally considered to be safe and effective. Common side effects of lubiprostone include nausea, diarrhea, abdominal pain and bloating, and the rare side effect dyspnea. Likely mechanisms for these side effects may be related to lubiprostone's primary action on small bowel secretion and the associated intestinal distension, as well as smooth muscle contraction.

AREAS COVERED

This article reviews the pharmacokinetic and safety profile of lubiprostone, with particular relevance to the two FDA-approved dosages.

EXPERT OPINION

Lubiprostone acts topically in the gut lumen and is almost completely metabolized in the gut lumen. Lubiprostone's M3 metabolite can be detected in low concentrations in the serum and may be responsible for some of its side effects. However, the exact mechanisms by which the side effects are produced are currently unknown.

Comprehensive self-management reduces the negative impact of irritable bowel syndrome symptoms on sexual functioning

BACKGROUND

Women with irritable bowel syndrome (IBS) report sexual dysfunction. Comprehensive self-management (CSM) intervention has been shown to reduce gastrointestinal, psychological, and somatic symptoms in IBS women. Whether this intervention also reduces sexual dysfunction is not known.

AIMS

We sought to compare demographic and clinical factors in IBS women with and without sexual dysfunction as defined by the Arizona sexual experiences scale (ASEX) and to test the effects of CSM treatment on sexual dysfunction scores and on the sexual relations subscale of an IBS quality of life (IBSQOL) scale which measures the effect of IBS on sexual QOL.

METHODS

IBS (Rome II) women enrolled in a randomized clinical trial of CSM treatment were characterized as having sexual dysfunction (N = 89) or not (N = 86) at baseline based on ASEX criteria. Baseline characteristics and symptoms were compared between the two groups. Post-intervention changes were compared between the CSM and the usual care arms of the randomized trial.

RESULTS

Women meeting ASEX criteria for sexual dysfunction were older, had higher lifetime depression and antidepressant use, more primary care/MD visits, fewer mental healthcare visits, and greater sleep disturbance than those without sexual dysfunction. No significant group differences in gastrointestinal or somatic symptoms were observed. Compared with usual care treatment, CSM increased sexual QOL scores and had a weaker effect on ASEX scores.

CONCLUSIONS

Severity of IBS symptoms at baseline did not differ between IBS women with or without sexual dysfunction. The CSM intervention can reduce the effect of IBS on sexual QOL.

Contrasting effects of linaclotide and lubiprostone on restitution of epithelial cell barrier properties and cellular homeostasis after exposure to cell stressors

BACKGROUND

Linaclotide has been proposed as a treatment for the same gastrointestinal indications for which lubiprostone has been approved, chronic idiopathic constipation and irritable bowel syndrome with constipation. Stressors damage the epithelial cell barrier and cellular homeostasis leading to loss of these functions. Effects of active linaclotide on repair of barrier and cell function in pig jejunum after ischemia and in T84 cells after treatment with proinflammatory cytokines, interferon-γ and tumor necrosis factor-α were examined. Comparison with effects of lubiprostone, known to promote repair of barrier function was carried out.

RESULTS

In ischemia-damaged pig jejunum, using measurements of transepithelial resistance, (3)H-mannitol fluxes, short-circuit current (Cl(-) secretion) and occludin localization, active linaclotide failed to effectively promote repair of the epithelial barrier or recovery of short-circuit current, whereas lubiprostone promoted barrier repair and increased short-circuit current. In control pig jejunum, 1 μM linaclotide and 1 μM lubiprostone both caused similar increases in short-circuit current (Cl(-) secretion). In T84 cells, using measurements of transepithelial resistance, fluxes of fluorescent macromolecules, occludin and mitochondrial membrane potential, active linaclotide was virtually ineffective against damage caused by interferon-γ and tumor necrosis factor-α, while lubiprostone protected or promoted repair of epithelial barrier and cell function. Barrier protection/repair by lubiprostone was inhibited by methadone, a ClC-2 inhibitor. Linaclotide, but not lubiprostone increased [cGMP]i as expected and [Ca(2+)]i and linaclotide depolarized while lubiprostone hyperpolarized the T84 plasma membrane potential suggesting that lubiprostone may lead to greater cellular stability compared to linaclotide. In T84 cells, as found with linaclotide but not with lubiprostone, transepithelial resistance was slightly but significantly decreased by guanylin, STa and 8-bromo cGMP and fluorescent dextran fluxes were increased by guanylin. However the physiological implications of these small but statistically significant changes remain unclear.

CONCLUSIONS

Considering the physiological importance of epithelial barrier function and cell integrity and the known impact of stressors, the finding that lubiprostone, but not active linaclotide, exhibits the additional distinct property of effective protection or repair of the epithelial barrier and cell function after stress suggests potential clinical importance for patients with impaired or compromised barrier function such as might occur in IBS.