Review article: The role of serotonergic agents in the treatment of patients with primary chronic constipation

Severity of constipation related to palonosetron during first-line chemotherapy: a retrospective observational study

PURPOSE

Palonosetron, a long-acting 5-HT₃ receptor antagonist, is an effective antiemetic agent for chemotherapy-induced nausea and vomiting; however, it sometimes causes severe constipation. The aim of the present study was to evaluate the severity of palonosetron-related constipation.

METHODS

We retrospectively analyzed the incidence and severity of constipation after intravenous administration of 0.75-mg palonosetron in 150 chemotherapy-naïve patients who received first-line chemotherapy at Saga University Hospital. Constipation was classified into grades 1-5 according to the Common Terminology Criteria for Adverse Events version 5.0. Multiple logistic regression analysis was performed to identify factors associated with palonosetron-related worsening of constipation to grade 2 or higher.

RESULTS

Palonosetron significantly increased the incidence and severity of constipation (incidence: before vs. after palonosetron, 35.4% vs. 74.0%, p < 0.0001, and severity: before vs. after palonosetron, 26.7% and 8.7% in grades 1 and 2, respectively, vs. 46.7%, 23.3%, and 4.0% in grades 1, 2, and 3, respectively, p < 0.0001). Despite the use of laxatives, 4.0% of patients had grade 3 constipation requiring manual evacuation. Combination treatment with aprepitant (odds ratio (OR), 10.9; 95% confidence interval (CI), 1.3-90.0; p = 0.026) and older age (OR, 1.25; 95% CI, 1.01-1.57; p = 0.039) were factors associated with the severity of constipation.

CONCLUSION

Constipation was more severe in patients receiving combination treatment with aprepitant than in those treated with palonosetron alone. Older age was also associated with increased risk of severe palonosetron-related constipation. Identification of risk factors can help target risk-based laxative therapy.

Novel Effects of Traditional Wooden Toothbrush on Bowel Motility Symptoms in Spinal Cord Injury Patients; Findings from a Pilot Quasi-experimental Study

BACKGROUND

The aim of this study was to investigate the therapeutic effect of traditional wooden toothbrush usage on most severe constipation, which usually occurs in spinal cord injury (SCI) patients.

METHODS

In a quasi-experimental study, 61 SCI patients were selected who had injuries in different spinal levels (cervical, thoracic, and lumbar), and severe constipation from one defection in a few days to 3 weeks. They were recommended to use traditional wooden toothbrush for 5 min twice a day, after breakfast and dinner, over a 6 weeks period. Two proper standard scales, called neurogenic bowel dysfunction (NBD), and "Constipation Assessment Scale (CAS)," were used for evaluating the changes in patients' gastrointestinal (GI) habits during the period of using the wooden toothbrush. Through these scales (NBD and CAS), the therapeutic effects of traditional wooden toothbrush usage on the severity of constipation before and after intervention were measured.

RESULTS

The mean of NBD and CAS scores were reduced significantly, from 8.95 ± 0.78 and 3.34 ± 0.28; respectively, to 3.03 ± 0.57 and 1.74 ± 0.25, after 6 weeks using traditional wooden toothbrush (P < 0.0001). There was a significant difference in terms of NBD scores in patients with different levels of injury (P < 0.01), particularly in patients with thoracic injury, before (10.52 ± 0.88) and after (3.13 ± 0.78) treatment, respectively (P < 0.0001). Eventually, all symptoms of bowel problems improved significantly after the intervention (P < 0.05).

CONCLUSIONS

The use of traditional wooden toothbrush lead to the improvement of bowel and defecation problems in SCI patients. Yet more studies, particularly randomized control clinical trials are needed to investigate the effect of using wooden toothbrush on other GI reflexes. In addition, if some clinical trials are devised to study the effects of wooden toothbrush on both conscious and unconscious patients in ICU, best results are expected to be found on keeping their mouth and teeth hygiene, as well as, getting rid of their constipations.

Diagnosis and management of chronic constipation in adults

Constipation is a heterogeneous, polysymptomatic, multifactorial disease. Acute or transient constipation can be due to changes in diet, travel or stress, and secondary constipation can result from drug treatment, neurological or metabolic conditions or, rarely, colon cancer. A diagnosis of primary chronic constipation is made after exclusion of secondary causes of constipation and encompasses several overlapping subtypes. Slow-transit constipation is characterized by prolonged colonic transit in the absence of pelvic floor dysfunction. This subtype of constipation can be identified using either the radio-opaque marker test or wireless motility capsule test, and is best treated with laxatives such as polyethylene glycol or newer agents such as linaclotide or lubiprostone. If unsuccessful, subspecialist referral should be considered. Dyssynergic defecation results from impaired coordination of rectoanal and pelvic floor muscles, and causes difficulty with defecation. The condition can be identified using anorectal manometry and balloon expulsion tests and is best managed with biofeedback therapy. Opioid-induced constipation is an emerging entity, and several drugs including naloxegol, methylnaltrexone and lubiprostone are approved for its treatment. In this Review, we provide an overview of the burden and pathophysiology of chronic constipation, as well as a detailed discussion of the available diagnostic tools and treatment options.

Lubiprostone Is Effective in the Treatment of Chronic Idiopathic Constipation and Irritable Bowel Syndrome: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

OBJECTIVE

To evaluate the efficacy and safety of lubiprostone in the treatment of chronic idiopathic constipation (CIC) and irritable bowel syndrome with constipation (IBS-C).

PATIENTS AND METHODS

We performed a literature search of the MEDLINE, Cochrane, Google Scholar, and ClinicalTrials.gov databases (from January 1, 2005, through January 31, 2015). Relevant studies meeting the inclusion criteria were manually searched by 2 independent reviewers. Efficacy outcomes evaluated at 1 week, 1 month, and 3 months of intervention were weekly frequency of spontaneous bowel movements, severity of constipation, consistency of stools, degree of abdominal pain/discomfort, degree of straining, and abdominal bloating.

RESULTS

Of 246 studies identified, data from 9 trials comprising 1468 patients (63.6%) in the lubiprostone group and 841 (36.4%) in the placebo group were analyzed. We found that lubiprostone treatment significantly improved the severity of constipation, stool consistency, abdominal pain, degree of straining, and abdominal bloating at 1 week (P≤.03) and 1 month (P≤.004), except for abdominal pain at 1 month, which was similar to that when treated with placebo (P=.21). At 3 months, except for abdominal bloating (P=.03), there was no difference between lubiprostone and placebo groups in all other outcomes (P≥.05). Adverse effects such as nausea, vomiting, and diarrhea were common (incidence rate, 2.4%-75%); however, the incidence of serious adverse effects was low (<5%) and was mostly unrelated to lubiprostone treatment.

CONCLUSION

Lubiprostone is a safe and efficacious drug for the treatment of chronic idiopathic constipation and irritable bowel syndrome with constipation, with limited adverse effects in 3 months of follow-up.

Efficacy and safety of prucalopride in adults and children with chronic constipation

INTRODUCTION

Chronic constipation (CC) is a debilitating condition with high prevalence rates both in children and adults. Despite the broad range of medical and pharmaceutical treatments, the bowel function does not restore in a fair amount of patients. Prucalopride is a first-in-class selective, high affinity serotonin 5-hydroxytryptamine type 4 (5-HT4) receptor agonist promoting gastro-intestinal prokinetic activity and has been evaluated for the treatment of CC.

AREAS COVERED

A PubMed search (1965 - 2014) using the following terms alone or in combination: prucalopride, 5-HT4, R093877, safety, toxicity, pharmacokinetics, pharmacodynamics, transit, cardiac, human ether-a-go-go related gene (hERG), arrhythmia, potassium current, elderly, children.

EXPERT OPINION

Prucalopride, a highly selective 5-HT4 receptor agonist, stimulates gastrointestinal motility and has been proven to be effective in the treatment of CC in adults by increasing stool frequency, reducing constipation-related symptoms and improving quality of life (QoL). The safety and tolerability have been proven to be excellent. More research would be preferable on the effect of prucalopride on men, children and in other gastrointestinal motility disorders.

The pathophysiology of chronic constipation

Constipation is broadly defined as an unsatisfactory defecation characterized by infrequent stools, difficult stool passage or both. The common approach to the pathophysiology of constipation groups the disorder into primary and secondary causes. Primary causes are intrinsic problems of colonic or anorectal function, whereas secondary causes are related to organic disease, systemic disease or medications. The normal process of colonic transit and defecation is discussed, and the etiology of constipation is reviewed.

Prucalopride: the evidence for its use in the treatment of chronic constipation

Introduction:

Chronic constipation is a common condition that is difficult to treat. Existing options for the treatment of patients with different subgroups of constipation are limited. A new efficacious and safe drug is needed to limit the frequently observed adverse effects induced by laxatives, to improve general wellbeing and quality of life, and to provide an alternative for enemas or even resectional surgery in patients in whom stimulant laxatives cause disabling adverse effects or fail to increase bowel movement frequency.

Aims:

The purpose of this article is to assess the current evidence supporting the use of the selective and high affinity serotonin-4 (5-HT₄) receptor agonist prucalopride in the management of chronic constipation.

Evidence review:

There are now convincing data from phase II and multicenter phase III randomized, double-blind, placebo-controlled trials that prucalopride treatment results in a clinically meaningful increase in the number of spontaneous complete bowel movements, a reduction of perceived severity of symptoms and improved disease-related quality of life in a significant proportion of patients. There is a rapid onset of the effect and the improvement is maintained for at least 12 weeks.

Prucalopride in a dose of up to 4 mg per day appeared generally well tolerated and devoid of serious cardiac events. Adverse events, most frequently headache and nausea, are usually mild or moderate and occur mainly during the first days of treatment. Prucalopride should be used with prudence and with careful assessment of the benefit-risk ratio until more clinical and electrophysiologic data become available, because relatively few patients have been exposed to the drug for long periods of time.

Place in therapy:

Prucalopride 1–2 mg once daily may be given to patients suffering from chronic constipation for whom laxatives do not provide adequate relief of their symptoms. Patients with severe constipation and slow transit, who frequently develop tolerance to stimulant laxatives, are also eligible for prucalopride treatment.

Emerging pharmacological therapies for the irritable bowel syndrome

The irritable bowel syndrome (IBS) is a symptom-based disorder defined by the presence of abdominal pain and altered bowel habits. Clinical presentations of IBS are diverse, with some patients reporting diarrhea, some constipation, and others a mixture of both. Like the varied clinical phenotypes, the pathogenesis of IBS is also diverse. IBS is not a single disease entity, but rather likely consists of several different disease states. This fact has important implications for the choices and efficacy of IBS treatment. This article reviews the IBS drugs that have reached phase II or III clinical trials.

Pharmacologic management of chronic constipation

Chronic constipation is a common digestive problem in North America, with significant psychosocioeconomic implications. Dietary and lifestyle measures and low-cost traditional over-the-counter laxatives are usually the first line of therapy but help only half of the patients. Several newer agents that act by increasing colonic peristalsis, altering colonic secretion, and/or antagonizing enteric opioid receptors have been developed that are effective in treating constipation and its related symptoms as well as improving quality of life. This article focuses on the pharmacology of traditional and newer agents for the treatment of constipation.

Impact of the 5-HT3 receptor channel system for insulin secretion and interaction of ginger extracts

The relevance of serotonin and in particular that of 5-HT(3) receptors is unequivocal with respect to emetic/antiemetic effects, but it is controversial with respect to antidiabetic effects. The effects of tropisetron (5-HT(3) receptor antagonist) and various ginger (Zingiber officinale) extracts (known to interact with the 5-HT(3) receptor channel system) were investigated. Serotonin (32 to 500 microM) inhibits insulin release (RIA) from INS-1 cells which is reversed by tropisetron (10 to 100 microM) and two different ginger extracts (spissum and an oily extract). Their effects are obvious even in the absence of serotonin but are more pronounced in its presence (doubled to tripled). Specific 5-HT(3) binding sites are present in INS-1 cells using 0.4 nM [3H] GR65630 in displacement experiments. The in vitro data with respect to ginger are corroborated by in vivo data on glucose-loaded rats showing that blood glucose (Glucoquant) is decreased by approximately 35% and plasma insulin (RIA) is increased by approximately 10%. Both the spissum extract and the oily ginger extract are effective in two other models: they inhibit [(14)C] guanidinium uptake into N1E-115 cells (model of 5-HT(3) effects) and relax rat ileum both directly and as a serotonin antagonistic effect. Other receptors addressed by ginger are 5-HT(2) receptors as demonstrated by using methysergide and ketanserin. They weakly antagonize the serotonin effect as well. It may be concluded that serotonin and in particular the 5-HT(3) receptor channel system are involved in modulating insulin release and that tropisetron and various ginger extracts can be used to improve a diabetic situation.

Serotonin pharmacology in the gastrointestinal tract: a review

Serotonin (5-hydroxytryptamine or 5-HT) plays a critical physiological role in the regulation of gastrointestinal (GI) function. 5-HT dysfunction may also be involved in the pathophysiology of a number of functional GI disorders, such as chronic constipation, irritable bowel syndrome and functional dyspepsia. This article describes the role of 5-HT in the enteric nervous system (ENS) of the mammalian GI tract and the receptors with which it interacts. Existing serotonergic therapies that have proven effective in the treatment of GI functional disorders and the potential of drugs currently in development are also highlighted. Advances in our understanding of the physiological and pathophysiological roles of 5-HT in the ENS and the identification of selective receptor ligands bodes well for the future development of more efficacious therapies for patients with functional GI disorders.

5-HT4 receptor agonists: similar but not the same

5-Hydroxytryptamine(4) (5-HT(4)) receptors are an interesting target for the management of patients in need of gastrointestinal (GI) promotility treatment. They have proven therapeutic potential to treat patients with GI motility disorders. Lack of selectivity for the 5-HT(4) receptor has limited the clinical success of the agonists used until now. For instance, next to their affinity for 5-HT(4) receptors, both cisapride and tegaserod have appreciable affinity for other receptors, channels or transporters [e.g. cisapride: human ether-a-go-go-related gene (hERG) is K(+) channel and tegaserod: 5-HT(1) and 5-HT(2) receptors]. Adverse cardiovascular events observed with these compounds are not 5-HT(4) receptor-related. Recent efforts have led to the discovery of a series of selective 5-HT(4) receptor ligands, with prucalopride being the most advanced in clinical development. The selectivity of these new compounds clearly differentiates them from the older generation compounds by minimizing the potential of target-unrelated side effects. The availability of selective agonists enables the focus to shift to the exploration of 5-HT(4) receptor-related differences between agonists. Based on drug- and tissue-related properties (e.g. differences in receptor binding, receptor density, effectors, coupling efficiency), 5-HT(4) receptor agonists are able to express tissue selectivity, i.e. behave as a partial agonist in some and as a full agonist in other tissues. Furthermore, the concept of ligand-directed signalling offers great opportunities for future drug development by enlarging the scientific basis for the generation of agonist-specific effects in different cell types, tissues or organs. Selective 5-HT(4) receptor agonists might thus prove to be innovative drugs with an attractive safety profile for better treatment of patients suffering from hypomotility disorders.

Risk factors for chronic constipation and a possible role of analgesics

Constipation has an estimated prevalence of 15% in the general population. However, the etiopathogenesis of this condition remains relatively obscure. This study sought to identify potentially novel risk factors for chronic constipation. A valid self-report questionnaire was mailed to an age- and gender-stratified random sample of Olmsted County, Minnesota residents aged 30-64 years. A logistic regression model that adjusted for age, gender and somatic symptom score (SSC) was used to identify factors associated with chronic constipation. People reporting symptoms of irritable bowel syndrome (IBS) were excluded. Of the 892 eligible subjects, 653 (73%) returned the survey. Among the 523 subjects not reporting IBS symptoms, chronic constipation was reported by 93 (18%) of the respondents. Chronic constipation was significantly associated with use of acetaminophen [>or=7 tablets per week, OR = 2.7 (1.1-6.6)]; aspirin [OR = 1.7 (1.0-2.7)]; non-steroidal anti-inflammatory drugs [OR = 1.8 (1.1-3.0)]; and SSC. No association was detected for age, gender, body mass index, marital status, smoking, alcohol, coffee, education level, food allergy, exposure to pets, stress, emotional support, or water supply. Chronic constipation is associated with use of acetaminophen, aspirin and non-steroidal anti-inflammatory drugs. The explanation of these associations requires further investigation.

Serotonin and its role in colonic function and in gastrointestinal disorders

Serotonin (5-HT) is most commonly thought of as a neurotransmitter in the central nervous system. However, the predominant site of serotonin synthesis, storage, and release is the enterochromaffin cells of the intestinal mucosa. Within the intestinal mucosa, serotonin released from EC cells activates neural reflexes associated with intestinal secretion, motility, and sensation. Two important receptors for serotonin that are located in the neural circuitry of the intestines are the 5-HT(3) and 5-HT(4) receptors; these are the targets of drugs designed to treat gastrointestinal disorders. 5-HT(3) receptor antagonists are used to treat nausea and emesis associated with chemotherapy and for functional disorders associated with diarrhea. 5-HT(4) receptor agonists are used as promotility agents to promote gastric emptying and to alleviate constipation. Because of the importance of serotonin in normal gut function and sensation, a number of studies have investigated potential changes in mucosal serotonin signaling in pathologic conditions. Despite the inconsistencies in the current literature, changes in serotonin signaling have now been demonstrated in inflammatory bowel disease, irritable bowel syndrome, postinfectious irritable bowel syndrome, and idiopathic constipation. Emerging evidence has led to many contradictory theories regarding serotonin signaling and its roles in the pathology of gut disorders. This review summarizes the current medications affecting serotonin signaling and provides an overview of our current knowledge of the changes in serotonin that occur in pathologic conditions.

Efficacy of tegaserod in chronic constipation in men

OBJECTIVES

Chronic constipation/idiopathic constipation is highly prevalent in western countries and traditional treatments are suboptimal. This multicenter study evaluated the efficacy and safety of tegaserod, a selective 5-HT(4) agonist and promotility agent, in men with chronic constipation.

METHODS

After screening and baseline phases, men with chronic constipation were randomized to receive either tegaserod 6 mg twice daily or placebo in a double-blind manner for 12 wk. Patients recorded symptoms using a diary. Primary efficacy variable was the response rate for an increase in complete spontaneous bowel movements (CSBMs) during the first 4 wk of double-blind treatment. Other efficacy measures included patient assessment of symptoms and satisfaction with symptom relief. Safety and tolerability were also evaluated.

RESULTS

In total, 322 patients were randomized to tegaserod (N = 158) or placebo (N = 164). Increases of at least one CSBM per wk during the first 4 wk of treatment observed for tegaserod compared with placebo (40.5%vs 29.3%, P= 0.03) were sustained throughout the 12-wk treatment period. Response rate for CSBM was also superior for tegaserod (P= 0.04 vs placebo) over the treatment period. Benefits for tegaserod over placebo were also observed for some secondary efficacy variables, however, statistical significance was not achieved at all weeks. Frequency of adverse events was similar with tegaserod and placebo.

CONCLUSIONS

Tegaserod 6 mg twice daily was effective and well tolerated in the treatment of chronic constipation in men. Tegaserod provided rapid relief of constipation within 1 wk and the effects were sustained for up to 12 wk.

Irritable bowel syndrome: update on colonic neuromuscular dysfunction and treatment

Recent discoveries regarding the relatively autonomous workings of the enteric nervous system have expanded our understanding of the pathophysiology of irritable bowel syndrome (IBS). However, the heterogeneity of the pathogenesis of IBS continues to create unique challenges for clinicians who care for these patients. Advances in our understanding of the structure and functions of the brain-gut axis and its interplay with other potentially important factors, such as genetic predisposition, inflammation, and psychological unrest, have led to new developments in the field of targeted pharmacotherapy for IBS sufferers. Therapies designed specifically to modulate gut motility, secretion, and/or sensation have been created and introduced into the marketplace in recent years, and additional designer formulations are in various stages of development. Concurrently, new discoveries of potentially beneficial effects of agents approved for other, often non-gastroenterologic, conditions continue to be reported. This article reviews the accumulating body of evidence supporting the importance of neuromuscular dysfunction as a central cause of IBS symptoms and provides a rationale for the discussion of current and future drug development.