Treatment of chronic constipation with cisapride and placebo

Evidence-Based Clinical Guidelines for Chronic Constipation 2023

The Japan Gastroenterological Association published the first version of its clinical guidelines for chronic constipation 2023. Based on the latest evidence, these guidelines describe the definition, classification, diagnostic criteria, diagnostic testing methods, epidemiology, pathophysiology, and treatment of chronic constipation. They include flowcharts for both diagnosis and treatment of chronic constipation. In the treatment of chronic constipation, the first step involves differentiating between secondary forms, such as organic disease-associated constipation, systemic disease-associated constipation, and drug-induced constipation. The next step is to determine whether the chronic constipation stems from a motility disorder, a form of primary chronic constipation. For functional constipation and constipation-predominant irritable bowel syndrome, treatment should be initiated after evaluating symptoms like reduced bowel movement frequency type or defecation difficulty type. The first line of treatment includes the improvement of lifestyle habits and diet therapy. The first drugs to consider for oral treatment are osmotic laxatives. If these are ineffective, secretagogues and ileal bile acid transporter inhibitors are candidates. However, stimulant laxatives are exclusively designated for as-needed use. Probiotics, bulk-forming laxatives, prokinetics, and Kampo medicines, for which there is insufficient evidence, are considered alternative or complementary therapy. Providing the best clinical strategies for chronic constipation therapy in Japan, these clinical guidelines for chronic constipation 2023 should prove useful for its treatment worldwide. The Japan Gastroenterological Association published the first version of its clinical guidelines for chronic constipation 2023. Based on the latest evidence, these guidelines describe the definition, classification, diagnostic criteria, diagnostic testing methods, epidemiology, pathophysiology, and treatment of chronic constipation. They include flowcharts for both diagnosis and treatment of chronic constipation. In the treatment of chronic constipation, the first step involves differentiating between secondary forms, such as organic disease-associated constipation, systemic disease-associated constipation, and drug-induced constipation. The next step is to determine whether the chronic constipation stems from a motility disorder, a form of primary chronic constipation. For functional constipation and constipation-predominant irritable bowel syndrome, treatment should be initiated after evaluating symptoms like reduced bowel movement frequency type or defecation difficulty type. The first line of treatment includes the improvement of lifestyle habits and diet therapy. The first drugs to consider for oral treatment are osmotic laxatives. If these are ineffective, secretagogues and ileal bile acid transporter inhibitors are candidates. However, stimulant laxatives are exclusively designated for as-needed use. Probiotics, bulk-forming laxatives, prokinetics, and Kampo medicines, for which there is insufficient evidence, are considered alternative or complementary therapy. Providing the best clinical strategies for chronic constipation therapy in Japan, these clinical guidelines for chronic constipation 2023 should prove useful for its treatment worldwide.

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

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

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

BACKGROUND AND PURPOSE

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

EXPERIMENTAL APPROACH

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

KEY RESULTS

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

CONCLUSION AND IMPLICATIONS

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

Oral domperidone has no additional effect on chronic functional constipation in children: a randomized clinical trial

BACKGROUND

Chronic constipation represents a common problem in children. The treatment of functional constipation is challenging. Some studies have investigated the effect of prokinetic agents as potential therapies for motility disorders of the lower gastrointestinal tract with paradoxical results. The present study aimed to investigate the effect of oral domperidone in the treatment of chronic functional constipation in children.

METHOD

A total of 105 children with chronic functional constipation (according to Rome III criteria) who were referred to the Pediatric Gastroenterology Clinic were recruited in this double-blind randomized clinical trial. The study subjects were randomly divided into two groups, the first of which received polyethylene glycol (PEG) solution 0.6 g/kg/day two times a day for 6 months and domperidone syrup 0.15 mL/kg three times a day for 3 months (case group) while the second one received PEG with the same dose for 6 months and placebo for 3 months with the same dose (control group). The two groups were compared regarding their symptoms and Rome III criteria through 1, 3, and 6 months following therapy. Primary outcome was response to treatment, and a response was defined as decrease in signs and symptoms that did not fulfill Rome III criteria. Secondary outcome measures were side effects during the course of treatment.

RESULTS

A significant difference was observed both before and after PEG and domperidone treatment and before and after PEG and placebo treatment regarding Rome III criteria. There was no significant difference in response to treatment between the two study groups during 1 (p = 1), 3 (p = 0.799), and 6 (p = 0.403) month follow up periods. Also, the two groups were not significantly different regarding the Rome III criteria during the mentioned follow up periods. There were no side effects during the course of treatment.

CONCLUSION

There was no additional effect of domperidone as adjunct to PEG in the treatment of children with constipation.

Discovery of TD-8954, a clinical stage 5-HT(4) receptor agonist with gastrointestinal prokinetic properties

The discovery of a series of 5-HT4 receptor agonists based on a novel 2-alkylbenzimidazole aromatic core is described. Optimization of the 2-substituent of the benzimidazole ring led to a series of agonists with subnanomolar binding affinity and moderate-to-high intrinsic activity relative to that of 5-HT. Consistent with our previously described multivalent design approach to this target, subsequent optimization of the linker and secondary binding group regions of the series afforded compound 18 (TD-8954), a potent and selective 5-HT4 receptor agonist in vitro with demonstrated prokinetic activity in multiple species.

Systematic review: cardiovascular safety profile of 5-HT(4) agonists developed for gastrointestinal disorders

BACKGROUND

The nonselective 5-HT(4) receptor agonists, cisapride and tegaserod have been associated with cardiovascular adverse events (AEs).

AIM

To perform a systematic review of the safety profile, particularly cardiovascular, of 5-HT(4) agonists developed for gastrointestinal disorders, and a nonsystematic summary of their pharmacology and clinical efficacy.

METHODS

Articles reporting data on cisapride, clebopride, prucalopride, mosapride, renzapride, tegaserod, TD-5108 (velusetrag) and ATI-7505 (naronapride) were identified through a systematic search of the Cochrane Library, Medline, Embase and Toxfile. Abstracts from UEGW 2006-2008 and DDW 2008-2010 were searched for these drug names, and pharmaceutical companies approached to provide unpublished data.

RESULTS

Retrieved articles on pharmacokinetics, human pharmacodynamics and clinical data with these 5-HT(4) agonists, are reviewed and summarised nonsystematically. Articles relating to cardiac safety and tolerability of these agents, including any relevant case reports, are reported systematically. Two nonselective 5-HT(4) agonists had reports of cardiovascular AEs: cisapride (QT prolongation) and tegaserod (ischaemia). Interactions with, respectively, the hERG cardiac potassium channel and 5-HT(1) receptor subtypes have been suggested to account for these effects. No cardiovascular safety concerns were reported for the newer, selective 5-HT(4) agonists prucalopride, velusetrag, naronapride, or for nonselective 5-HT(4) agonists with no hERG or 5-HT(1) affinity (renzapride, clebopride, mosapride).

CONCLUSIONS

5-HT(4) agonists for GI disorders differ in chemical structure and selectivity for 5-HT(4) receptors. Selectivity for 5-HT(4) over non-5-HT(4) receptors may influence the agent's safety and overall risk-benefit profile. Based on available evidence, highly selective 5-HT(4) agonists may offer improved safety to treat patients with impaired GI motility.

Cisapride: what can we learn from the rise and fall of a prokinetic?

Cisapride, the prototype serotonergic agent, evolved from a body of research that defined the key roles of serotonergic receptors in gastrointestinal motor and sensory function. Impressed by its in vitro properties and encouraged by clinical trial data, cisapride became the drug of choice for the treatment of a wide range of motility disorders and clinicians appeared impressed by its efficacy and comfortable with its side-effect profile. Once serious cardiac events began to be reported in association with cisapride therapy, dark clouds rapidly gathered and soon enveloped the drug, leading to its widespread withdrawal from markets. What lessons can we learn from the story of cisapride? How can its brief but spectacular rise and equally sensational demise inform the development of new drugs which are so sorely needed in the management of motility and functional gastrointestinal disorders? This review explores the background to the development of cisapride, its history in clinical trials and the experience with adverse events and, in so doing, attempts to identify lessons for the future in the therapeutics of enteric neuromodulatory drugs.

The Pharmacology of TD-8954, a Potent and Selective 5-HT(4) Receptor Agonist with Gastrointestinal Prokinetic Properties

This study evaluated the in vitro and in vivo pharmacological properties of TD-8954, a potent and selective 5-HT(4) receptor agonist. TD-8954 had high affinity (pK(i) = 9.4) for human recombinant 5-HT(4(c)) (h5-HT(4(c))) receptors, and selectivity (>2,000-fold) over all other 5-hydroxytryptamine (5-HT) receptors and non-5-HT receptors, ion channels, enzymes and transporters tested (n = 78). TD-8954 produced an elevation of cAMP in HEK-293 cells expressing the h5-HT(4(c)) receptor (pEC(50) = 9.3), and contracted the guinea pig colonic longitudinal muscle/myenteric plexus preparation (pEC(50) = 8.6). TD-8954 had moderate intrinsic activity in the in vitro assays. In conscious guinea pigs, subcutaneous administration of TD-8954 (0.03-3 mg/kg) increased the colonic transit of carmine red dye, reducing the time taken for its excretion. Following intraduodenal dosing to anesthetized rats, TD-8954 (0.03-10 mg/kg) evoked a dose-dependent relaxation of the esophagus. Following oral administration to conscious dogs, TD-8954 (10 and 30 μg/kg) produced an increase in contractility of the antrum, duodenum, and jejunum. In a single ascending oral dose study in healthy human subjects, TD-8954 (0.1-20 mg) increased bowel movement frequency and reduced the time to first stool. It is concluded that TD-8954 is a potent and selective 5-HT(4) receptor agonist in vitro, with robust in vivo stimulatory activity in the gastrointestinal (GI) tract of guinea pigs, rats, dogs, and humans. TD-8954 may have clinical utility in patients with disorders of reduced GI motility.

Cisapride for intestinal constipation

BACKGROUND

Cisapride is a propulsive agent, withdrawn from most of the world's health institutes because of its recorded fatalities in addition to serious side effects such as severe arrhythmias. However it is widely available in third world countries and can be easily purchased through the Internet.  We did a systematic review to assess its efficacy and safety in relieving constipation.

OBJECTIVES

The primary objective is to assess Cisapride's role and safety as a prokinetic drug in the management of constipation and constipation predominant Irritable bowel syndrome (C-IBS).The secondary objective is to assess Cisapride's efficacy in improving symptoms of constipation and IBS.

SEARCH STRATEGY

Cochrane methodology was followed to find available RCTs that assessed the efficacy of cisapride. Electronic databases searched November 2009:Cochrane Central Register of Controlled Trials (CENTRAL) on The Cochrane Library 2009 issue 4MEDLINE (from 1966)EMBASE (from 1980)

SELECTION CRITERIA

All RCTs comparing cisapride to placebo or to active comparators were included. We included patients of all ages who had functional constipation or C-IBS.

DATA COLLECTION AND ANALYSIS

Eight RCTs were included, comparing cisapride to a placebo on patients with constipation or C-IBS. The studies were pooled and analysed and a combined effect was calculated using meta-analysis.

MAIN RESULTS

8 trials included in the review for a total 424 patients who were randomised to Cisapride or placebo, of which 157 were children and 284 were female. Intervention duration was 8 to 12 weeks. Dosage of Cisapride in the adult and children trials were 5mg TDS and 0.2mg/kg/dose TDS respectively.Cisapride showed significant benefit in investigators' assessment of clinical improvement (OR: 0.45, P=0.03), likelihood of passing daily stools (OR: 0.22, P<0.001), passage of normal stools (OR: 0.06, P<0.001) and total gastrointestinal transit time (MD: -19.47, P<0.00001). However Cisapride showed no benefit in global improvement of symptoms (MD: 0.11, P=0.99), abdominal pain (MD: 1.94, P=0.56), stool frequency: weekly (MD: 3.36, P=0.11), visual analogue scale (MD: -0.23, P=0.66), stool consistency (MD: 0.32, P=0.50), bloating (MD: 3.93, P=0.44), persistent bloating(OR: 1.11, P=0.83), 'feeling of incomplete evacuation' (MD: -3.80, P=0.08), straining (MD -0.95, p=0.19).

AUTHORS' CONCLUSIONS

No clear benefit can be demonstrated with cisapride. We do not feel that cisapride can be justifiably used for chronic constipation or irritable bowel disease given its side effects of arrhythmia and associated 175 recorded deaths.

Role of prucalopride, a serotonin (5-HT(4)) receptor agonist, for the treatment of chronic constipation

Constipation affects up to a quarter of the population in developed countries and is associated with poor quality of life and significant economic burden. Many patients with chronic constipation are dissatisfied with current therapy due to lack of long-term efficacy or side effects. Previous nonselective 5-hydroxytryptamine receptor 4 (5-HT₄) agonists have been associated with significant interactions with other receptors (5-HT_1B, 5-HT_1D, and 5-HT_2B for tegaserod; hERG for cisapride), leading to adverse cardiovascular events resulting in withdrawal of these drugs from the market. Prucalopride is a novel gastrointestinal prokinetic agent. It acts as a high affinity, highly-selective 5-HT₄ agonist. Its efficacy in patients with chronic constipation has been demonstrated in several phase II and phase III clinical trials showing significant improvements in bowel transit, bowel function, gastrointestinal symptoms, and quality of life, with benefit maintained for up to 24 months in open label, multicenter, follow-up studies. Prucalopride’s high selectivity for the 5-HT₄ receptor may explain its favorable safety and tolerability profiles, even in elderly subjects with stable cardiovascular disease. Prucalopride is a well tolerated and efficacious prokinetic medication that should enhance the treatment of chronic constipation unresponsive to first-line treatments.

The in vivo gastrointestinal activity of TD-5108, a selective 5-HT(4) receptor agonist with high intrinsic activity

The in vivo preclinical pharmacodynamic profile of TD-5108, a selective 5-HT(4) receptor agonist with high intrinsic activity, was compared to that of the clinically studied gastrointestinal pro-kinetic agents, tegaserod, cisapride and mosapride. The activity of TD-5108 was evaluated in guinea pig colonic transit, rat oesophageal relaxation and dog gastrointestinal smooth muscle contractility models. Subcutaneous administration of TD-5108, tegaserod, cisapride and mosapride increased guinea pig colonic transit (rank order of potencies: TD-5108 > tegaserod > cisapride > mosapride). Following intravenous and intraduodenal dosing, TD-5108, tegaserod, cisapride and mosapride produced dose-dependent relaxation of the rat oesophagus. On a molar basis, TD-5108 was approximately twofold less potent than tegaserod following intravenous dosing but 6- or 86-fold more potent than cisapride or mosapride, respectively, and 9- or 18-fold more potent than tegaserod or cisapride, respectively, after intraduodenal administration. Orally dosed TD-5108 increased the contractility of the canine antrum, duodenum and jejunum with higher potency than tegaserod. The selective 5-HT(4) receptor agonist, TD-5108, demonstrates robust in vivo activity in the guinea pig, rat and dog gastrointestinal tracts.

The in vitro pharmacological profile of TD-5108, a selective 5-HT(4) receptor agonist with high intrinsic activity

The in vitro pharmacological profile of TD-5108, a novel, selective 5-HT(4) receptor agonist, was compared to that of clinically efficacious gastroprokinetic 5-HT(4) receptor agonists. TD-5108 produced an elevation of cyclic adenosine monophosphate in human embryonic kidney 293 cells expressing the human recombinant 5-HT(4(c)) (h5-HT(4(c))) receptor (pEC(50) = 8.3) and 5-HT(4) receptor-mediated relaxation of the rat esophagus (pEC(50) = 7.9) and contraction of the guinea pig colon (pEC(50) = 7.9). In all in vitro assays, TD-5108 was a high intrinsic activity agonist, unlike tegaserod, mosapride, and cisapride which, in the majority of test systems, had lower intrinsic activity. TD-5108 had high affinity (pK (i) = 7.7) and selectivity (> or =25-fold) for h5-HT(4(c)) receptors over other biogenic amine receptors. TD-5108 was >500-fold selective over other 5-HT receptors (including h5-HT(2B) and h5-HT(3A)) and, at 3 microM, had no effect on human ether-à-go-go-related gene K+ channels. In conclusion, TD-5108 is a selective 5-HT(4) receptor agonist in vitro. The high intrinsic activity and preferential binding of TD-5108 to 5-HT4 over other 5-HT receptors may result in an improved clinical profile for the treatment of gastrointestinal disorders of reduced motility.

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.

The rationale, efficacy and safety evidence for tegaserod in the treatment of irritable bowel syndrome

A growing body of evidence implicates abnormal serotonergic regulation of gastrointestinal function in the pathogenesis of the irritable bowel syndrome (IBS). Drugs targeting this system are therefore attractive concepts. The partial 5-HT4 receptor agonist tegaserod might be predicted to have positive therapeutic effects on a constipated and uncomfortable gut. However, IBS runs a chronic, benign course and carries no associated mortality, so it is imperative that the safety profile of new pharmacological agents made available to physicians is exemplary. The authors review the evidence for 5-HT in the aetiology of IBS and its symptoms, and the data available concerning the partial 5-HT4 receptor agonist tegaserod, in terms of rationale, efficacy and safety.

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

Chronic constipation is a highly prevalent disorder that is associated with significant direct and indirect costs and has substantial impact on patient quality of life. It is more common among women and non-white populations and is evenly distributed across adult age groups. Constipation is a heterogeneous disorder associated with multiple symptoms and aetiologies. Recent research has increased our understanding of the pathogenesis of this disorder and the central role of the neurotransmitter serotonin in mediating gastrointestinal motility, secretion and sensation. Abnormal serotonin signalling and reuptake appear to play central roles in the symptoms of a subset of patients with chronic constipation. This observation provides a rationale for the use of targeted serotonergic agents for the treatment of chronic constipation. As the role of serotonin in gastrointestinal function is further elucidated and additional candidate drugs are developed, it is likely that serotonergic agents will afford additional treatment options for patients with chronic constipation. This article provides a concise review of the evidence supporting a role for serotonin in the pathogenesis of chronic constipation and a summary of the currently available evidence supporting the use of serotonergic agents for this disorder.

Efficacy and safety of traditional medical therapies for chronic constipation: systematic review

OBJECTIVES

Constipation is common, and its treatment is unsatisfactory. Although many agents have been tried, there are limited data to support their use. Our aim was to undertake a systematic review of the efficacy and safety of traditional medical therapies for chronic constipation and to make evidence-based recommendations.

METHODS

We searched the English literature for drug trials evaluating treatment of constipation by using MEDLINE and PUBMED databases from 1966 to 2003. Only studies that were randomized, conducted on adult subjects, and published as full manuscripts were included. Studies were assigned a quality score based on published methodology. Standard forms were used to abstract data regarding study design, duration, outcome measures, and adverse events. By using the cumulative evidence of published data for each agent, recommendations were made regarding their use following the United States Preventive Services Task Force guidelines.

RESULTS

Good evidence (Grade A) was found to support the use of polyethylene glycol (PEG) and tegaserod. Moderate evidence (Grade B) was found to support the use of psyllium, and lactulose. There was a paucity of quality data regarding many commonly used agents including milk of magnesia, senna, bisacodyl, and stool softeners.

CONCLUSIONS

There is good evidence to support the use of PEG, tegaserod, lactulose, and psyllium. Surprisingly, there is a paucity of trials for many commonly used agents. These aspects should be considered when designing trials comparing new agents with traditional therapies because their use may not be well validated.

Management of opioid-induced bowel dysfunction in cancer patients

The gastrointestinal (GI) effects of morphine and other opioids may result in opioid-induced bowel dysfunction (OBD) and the need for treatment. Although OBD is very common in morphine-treated patients, it is usually under-diagnosed. Opioids deliver their GI effect through central and peripheral mechanisms. Laxatives are the pharmaceuticals prescribed most in this area. Prokinetics as well as cholinergic agonists have been used satisfactorily. One-third of patients with OBD have to be treated rectally. The use of opioid antagonists has been favored, but the bioavailability of oral forms is poor. Opioid antagonists with a quaternary structure have a high affinity for peripheral opioid receptors and therefore do not interfere with the analgesia, nor do they generate alkaloid withdrawal syndrome. Opioid rotation is another strategy for maintaining or improving analgesic quality directed toward decreasing the effects of previous opiates on the GI tract.

Myths and misconceptions about chronic constipation

There are many strongly held beliefs about constipation that are not evidence based. The purpose of this review is to address these beliefs concerning various aspects of constipation. There is no evidence to support the theory that diseases may arise via "autointoxication," whereby poisonous substances from stools within the colon are absorbed. Dolichocolon, defined as an elongated colon, should not be seen as a cause of constipation. The role of sex hormones altering gut function during the menstrual cycle appears to be minimal. During pregnancy they may play a role in slowing gut transit. Hypothyroidism can cause constipation, but among patients presenting with constipation, hypothyroidism is rare. A diet poor in fiber should not be assumed to be the cause of chronic constipation. Some patients may be helped by a fiber-rich diet but many patients with more severe constipation get worse symptoms when increasing dietary fiber intake. There is no evidence that constipation can successfully be treated by increasing fluid intake unless there is evidence of dehydration. In the elderly constipation may correlate with decreased physical activity, but many cofactors are likely to play a role. Intervention programs to increase physical activity as part of a broad rehabilitation program may help. It is unlikely that stimulant laxatives at recommended doses are harmful to the colon. A proportion of patients with chronic constipation is dependent of laxatives to achieve satisfactory bowel function, but this is not the result of prior laxative intake. Tolerance to stimulant laxatives is uncommon. There is no indication for the occurrence of "rebound constipation" after stopping laxative intake. While laxatives may be misused, there is no potential for addiction.

Role of serotonin in the pathophysiology of the irritable bowel syndrome

The irritable bowel syndrome (IBS) is a complex disorder that is associated with altered gastrointestinal motility, secretion, and sensation. Serotonin (5-HT) is an important neurotransmitter and paracrine signalling molecule in the gastrointestinal tract. 5-HT release from enterochromaffin (EC) cells initiates peristaltic, secretory, vasodilatory, vagal and nociceptive reflexes. The enteric nervous system (ENS) comprises a semiautonomous effector system that is connected to the central autonomic network. Parasympathetic and sympathetic nerves modulate the ENS via afferent and efferent communications. Ongoing, bidirectional brain-gut interactions involving 5-HT pathways occur that significantly influence the effector systems. Altered 5-HT signalling may lead to both intestinal and extraintestinal symptoms in IBS. 5-HT directly and indirectly affects intestinal motor and secretory function and abnormalities may lead to either constipation or diarrhea. 5-HT modulates sensation and perception of visceral stimulation at peripheral and central sites. Therapeutic agents targeting altered 5-HT signalling may provide new, effective treatments for patients with IBS.

The 5-HT4 receptor agonist, tegaserod, is a potent 5-HT2B receptor antagonist in vitro and in vivo

1 Tegaserod (Zelnorm) is a potent 5-hydroxytryptamine4 (5-HT4) receptor agonist with clinical efficacy in disorders associated with reduced gastrointestinal motility and transit. The present study investigated the interaction of tegaserod with 5-HT2 receptors, and compared its potency in this respect to its 5-HT4 receptor agonist activity. 2 Tegaserod had significant binding affinity for human recombinant 5-HT2A, 5-HT2B and 5-HT2C receptors (pKi=7.5, 8.4 and 7.0, respectively). The 5-HT2B receptor-binding affinity of tegaserod was identical to that at human recombinant 5-HT4(c) receptors (mean pKi=8.4) in human embryonic kidney-293 (HEK-293) cells stably transfected with the human 5-HT4(c) receptor. 3 Tegaserod (0.1-3 microm) inhibited 5-HT-mediated contraction of the rat isolated stomach fundus potently (pA2=8.3), consistent with 5-HT(2B) receptor antagonist activity. Tegaserod produced, with similar potency, an elevation of adenosine 3',5' cyclic monophosphate in HEK-293 cells stably transfected with the human 5-HT4(c) receptor (mean pEC50=8.6), as well as 5-HT4) receptor-mediated relaxation of the rat isolated oesophagus (mean pEC50=8.2) and contraction of the guinea-pig isolated colon (mean pEC50=8.3). 4 Following subcutaneous administration, tegaserod (0.3 or 1 mg kg(-1)) inhibited contractions of the stomach fundus in anaesthetized rats in response to intravenous dosing of alpha-methyl 5-HT (0.03 mg kg(-1)) and BW 723C86 (0.3 mg kg(-1)), selective 5-HT2B receptor agonists. At similar doses, tegaserod (1 and 3 mg kg(-1) subcutaneously) evoked a 5-HT4 receptor-mediated increase in colonic transit in conscious guinea-pigs. 5 The data from this study indicate that tegaserod antagonizes 5-HT2B receptors at concentrations similar to those that activate 5-HT4 receptors. It remains to be determined whether this 5-HT2B receptor antagonist activity of tegaserod contributes to its clinical profile.

Serotonergic modulating drugs for functional gastrointestinal diseases

After many years of basic research we have now begun to learn how to manipulate the serotonergic mechanisms within the gut. This has lead to a number of significant advances including 5HT3 antagonists for the treatment of functional diarrhoea, 5HT4 agonists for the treatment of constipation and 5HT1 agonists for the treatment of impaired fundal relaxation. Initial enthusiasm has been somewhat dented by the withdrawal of alosetron because of ischaemic colitis, but it remains to be seen whether this adverse event will be seen with other 5HT3 antagonists. Finally it should be recognized that, in a substantial proportion of patients attending clinics complaining of functional symptoms, anxiety is a major component. The drugs so far described are by and large devoid of CNS effects. It remains possible therefore that a drug which combines both peripheral and central effects would likely to be beneficial.

Tegaserod, a 5-HT(4) receptor partial agonist, relieves symptoms in irritable bowel syndrome patients with abdominal pain, bloating and constipation

AIM

To investigate the efficacy and safety of tegaserod, a novel 5-HT(4) receptor partial agonist, in a randomized, double-blind, placebo-controlled, 12-week treatment, multicentre study.

METHODS

Eight hundred and eighty-one patients with irritable bowel syndrome, characterized by abdominal pain, bloating and constipation, received tegaserod, 2 mg b.d. or 6 mg b.d., or placebo for 12 weeks.

RESULTS

Tegaserod, 2 mg b.d. and 6 mg b.d., showed a statistically significant relief of overall irritable bowel syndrome symptoms, measured by a weekly, self-administered questionnaire. At end-point, treatment differences from placebo were 12.7% and 11.8% for 2 mg b.d. and 6 mg b.d., respectively. The effect of tegaserod was noted as early as week 1, and was sustained over the 12-week treatment period. Individual irritable bowel syndrome symptoms assessed daily also showed a statistically significant improvement of abdominal discomfort/pain, number of bowel movements and stool consistency, and a favourable trend for reducing days with significant bloating. Adverse events were similar in all groups, with transient diarrhoea being the only adverse event seen more frequently with tegaserod than placebo.

CONCLUSIONS

Based upon the results of this study, tegaserod offers rapid and sustained relief of the abdominal pain and constipation associated with irritable bowel syndrome. Tegaserod is also well tolerated.

The in vitro pharmacological profile of prucalopride, a novel enterokinetic compound

Prucalopride is a novel enterokinetic compound and is the first representative of the benzofuran class. We set out to establish its pharmacological profile in various receptor binding and organ bath experiments. Receptor binding data have demonstrated prucalopride's high affinity to both investigated 5-HT(4) receptor isoforms, with mean pK(i) estimates of 8.60 and 8.10 for the human 5-HT(4a) and 5-HT(4b) receptor, respectively. From the 50 other binding assays investigated in this study only the human D(4) receptor (pK(i) 5.63), the mouse 5-HT(3) receptor (pK(i) 5.41) and the human sigma(1) (pK(i) 5.43) have shown measurable affinity, resulting in at least 290-fold selectivity for the 5-HT(4) receptor. Classical organ bath experiments were done using isolated tissues from the rat, guinea-pig and dog gastrointestinal tract, using various protocols. Prucalopride was a 5-HT(4) receptor agonist in the guinea-pig colon, as it induced contractions (pEC(50)=7.48+/-0.06; insensitive to a 5-HT(2A) or 5-HT(3) receptor antagonist, but inhibited by a 5-HT(4) receptor antagonist) as well as the facilitation of electrical stimulation-induced noncholinergic contractions (blocked by a 5-HT(4) receptor antagonist). Furthermore, it caused relaxation of a rat oesophagus preparation (pEC(50)=7.81+/-0.17), in a 5-HT(4) receptor antagonist sensitive manner. Prucalopride did not cause relevant inhibition of 5-HT(2A), 5-HT(2B), or 5-HT(3), motilin or cholecystokinin (CCK(1)) receptor-mediated contractions, nor nicotinic or muscarinic acetylcholine receptor-mediated contractions, up to 10 microM. It is concluded that prucalopride is a potent, selective and specific 5-HT(4) receptor agonist. As it is intended for treatment of intestinal motility disorders, it is important to note that prucalopride is devoid of anti-cholinergic, anticholinesterase or nonspecific inhibitory activity and does not antagonise 5-HT(2A), 5-HT(2B) and 5-HT(3) receptors or motilin or CCK(1) receptors.

AGA technical review on constipation. American Gastroenterological Association

This literature review and the recommendations therein were prepared for the American Gastroenterological Association Clinical Practice and Practice Economics Committee. The paper was approved by the Committee on March 4, 2000, and by the AGA Governing Board on May 21, 2000.

Cisapride for the treatment of constipation in children: A double-blind study

OBJECTIVE

To determine whether cisapride is effective in the treatment of children with constipation.

STUDY DESIGN

Double-blind, placebo-controlled study in which children with chronic constipation were randomly assigned to treatment with cisapride or placebo for 12 weeks.

RESULTS

Forty children were enrolled, and 36 completed the therapy. Treatment successes occurred in 13 of 17 (76%) subjects in the cisapride group and 8 of 19 (37%) subjects in the placebo group (P <.03). The odds ratio for response after cisapride administration was 8.2 times higher (95% CI 1.3 to 49.4). During cisapride therapy, there was a significant improvement in number of spontaneous bowel movements per week (from 0.9 +/- 0.1 to 4.1 +/- 1.1), and there was a significant decrease in number of fecal soiling episodes per day (1.8 +/- 0.5 to 0.08 +/- 0.4), percent with encopresis (82% vs 23%), number of laxative doses per week (from 10.3 +/- 2.6 to 0.8 +/- 0.6), percent using laxatives (77% to 24%), and total gastrointestinal transit time (from 115.0 +/- 3.7 hours to 77.0 +/- 11.1 hours). With placebo, there were no significant changes in the number of spontaneous bowel movements (from 1.0 +/- 0.8 to 2.2 +/- 0.6), percent with encopresis (74% vs 47%), or total gastrointestinal transit time (from 112.5 +/- 4.9 hours to 95.4 +/- 9.8 hours); but there was a significant decrease in number of fecal soiling episodes per day (from 1.3 +/- 0.4 to 0.4 +/- 0.2) and number of laxative doses used per week (from 11.5 +/- 2.9 to 2.05 +/- 0.7). The final number of spontaneous bowel movements, fecal soiling episodes, laxatives used, or percent patients with encopresis was not different when patients receiving cisapride were compared with those receiving placebo.

CONCLUSION

Cisapride was effective in the treatment of children with constipation.

A prospective, randomized, double-blinded, placebo-controlled trial of cisapride after colorectal surgery

BACKGROUND

The predominant factor prolonging hospitalization and delaying oral intake after colorectal surgery continues to be return of large bowel function. We investigated the effect of the cisapride on postoperative bowel motility.

METHODS

Patients were started on cisapride versus a placebo on postoperative day 1 after colorectal surgery. Endpoints included the time to patients' first bowel movement, time of advancement to regular diet, time of hospitalization, and cost analysis. Results were analyzed using a Mann-Whitney test.

RESULTS

Thirty-five patients were entered in the study, consisting of 17 in the cisapride group and 18 in the placebo group. The median time to first bowel movement, advancement of diet, and hospital discharge was 1 day less in the cisapride group compared with the placebo group (P <0.05). There was a substantial cost savings in the study group.

CONCLUSIONS

Cisapride use results in statistically significant improvement in postoperative bowel motility. Cisapride should be added as adjunct treatment in postoperative care after colorectal surgery.

Constipation, diarrhea, and irritable bowel syndrome

Constipation, diarrhea, and irritable bowel syndrome are commonly encountered in the primary care practice. Most episodes of constipation and diarrhea are benign and self-limited. Patients with chronic constipation should undergo a screening evaluation to exclude organic disease, after which most can be managed successfully with dietary modification and fiber supplementation. The cause of chronic diarrhea usually can be discerned clinically, with irritable bowel syndrome, inflammatory bowel disease, and lactose intolerance being diagnosed most frequently. Irritable bowel syndrome is a functional gastrointestinal disorder characterized by abdominal pain and disordered defecation, which is successfully managed with a strong physician-patient relationship and periodic pharmacologic intervention.

Challenging problems presenting as constipation

Patients who seek medical care for constipation present challenges which may involve communication problems, difficulties in diagnosis, lack of optimal therapy, uncorrectable underlying disorders, or psychiatric issues which complicated management. This review describes some of these challenges, and presents management approaches that may increase the likelihood of satisfactory treatment outcomes. Situations which are reviewed include the diagnostic evaluation of the new patient with constipation; syndromes of uncertain pathophysiology including irritable bowel syndrome, slow transit constipation, and pelvic floor dysfunction; constipation associated with neurologic disorders including spinal cord injury, Parkinson's disease, and multiple sclerosis; and psychiatric issues which complicate the management of constipation, including recognition of associated psychiatric diseases, unusual attitudes toward bowel function, eating disorders, and referral for psychiatric care.

Scintigraphic measurement of regional gastrointestinal transit in the dog

Scintigraphic techniques can measure sequentially gastric emptying, small bowel transit, and colonic transit in humans, and comparable methods for experimental studies in animals would be useful. We developed such a method in dogs and examined the effects of prokinetic drugs on regional transit. Two isotopes were given to fasting dogs. Polystyrene pellets labeled with 99mTc were mixed in a can of dog food and 111In- labeled pellets were given in a gelatin capsule coated with a pH-sensitive polymer, designed to dissolve in the distal bowel. Gamma camera images were obtained for up to 24 h. Prokinetic drugs were given by intravenous injection. Duplicate baseline studies showed good agreement in seven dogs. In a second group (n = 4), intra- and interanimal variabilities were established. Two novel prokinetic drugs (AU-116 and AU-130) accelerated small bowel and colonic transit. A simple noninvasive method for measuring whole gut transit in dogs was developed and validated. Two new prokinetics accelerated small bowel and colonic transit.

A novel series of N-(hexahydro-1,4-diazepin-6-yl) and N-(hexahydroazepin- 3-yl)benzamides with high affinity for 5-HT3 and dopamine D2 receptors

A novel series of benzamides with a hexahydro-1,4-diazepine or hexahydroazepine ring in the amine moiety were prepared, and their binding affinities for 5-HT3 and dopamine D2 receptors were evaluated. The R isomer of the 1-ethyl-4-methylhexahydro-1,4-diazepinylbenzamide (R)-22 had potent affinity for both receptors. The R-enantiomer of the corresponding 1-ethylhexahydroazepinylbenzamide 28 showed potent affinity for dopamine D2 receptors with reduced affinity for 5-HT3 receptors, while the S isomer was found to be a potent and selective 5-HT3 receptor antagonist.

Use of cisapride in treatment of constipation in children

BACKGROUND

Chronic constipation is a common problem in children. We observed the effects of cisapride in the management of idiopathic constipation in children.

METHODS

Thirty-seven children with a history of constipation (i.e., pain and difficulty or delay in defecation for > 3 months) were recruited and randomly assigned to 8 weeks of treatment with either cisapride, 0.2 mg/kg three times daily, or matching placebo after a 2-week run-in period in a double-blind, parallel-group study design. In phase 1 (2 weeks), patients had plain abdominal radiographs to assess degree of faecal load, and those with impaction were given laxatives. After satisfactory clearance of faeces, total gastrointestinal transit time and orocaecal transit time were measured. In phase 2, after 8 weeks of treatment with either cisapride or placebo (0.2 mg/kg t.d.s.), the transit studies were repeated.

RESULTS

Compared with placebo, cisapride did not improve either stool frequency or transit time in this study population.

CONCLUSION

This study did not demonstrate a clinical role for the use of cisapride in the treatment of idiopathic constipation in children.

Newer aspects of the irritable bowel syndrome

IBS is a challenging, functional GI disorder that affects many individuals around the world. Early life experiences, the biologic nature of the condition, and the psychosocial milieu interact to affect the severity and outcome of symptoms. Most people do not seek medical attention for their GI symptoms, or they require intermittent, limited medical therapy and assurance from their physician. Fewer patients, but still a significant number, demand frequent interaction with their physician, who may select pharmacotherapy or psychological and behavioral treatments to control symptoms, depending on the severity. A biopsychosocial approach with attention to the patient-doctor relationship is recommended as the basis for treatment.

Cisapride in chronic idiopathic constipation: clinical response and effect on colonic transit time

OBJECTIVES

To evaluate the effect of cisapride on the total and segmental colonic transit times (CTT's) and on the clinical symptoms in patients with chronic idiopathic constipation, and to elucidate whether the correction of the CTT parallels the symptomatic improvement.

METHODS

An open prospective trial of cisapride, 10 mg t.i.d. orally for 8 weeks, was done in 25 adult patients (M: F6: 19) with chronic idiopathic constipation of 1 year or longer duration. CTT was measured at baseline and after 8 weeks of cisapride therapy. Frequency, consistency and difficulty in passage of bowel movements were evaluated at baseline and after 2, 4 and 8 weeks of cisapride therapy.

RESULTS

19 cases continued to participate until the end of 4 weeks of therapy and 15 cases completed the entire 8 weeks' trial. No serious side effect was experienced during the study period. Total and right segmental CTT's shortened with 8 weeks of cisapride treatment. Defecation frequency increased and difficulty in stool passage improved with 2 to 8 weeks of treatment. Stool consistency had a tendency toward normal after 8 weeks of treatment (p = 0.06). The global response was excellent in 7 cases (46.7%), good in 5 (33.3%) and poor in 3 (20.0%). If all dropped-out cases were assumed to be poor responders, the good or excellent responders after 8 weeks of cisapride might be 48.0% of all recruited patients. The response to cisapride could not be predicted by the various clinical parameters of the patients.

CONCLUSION

Cisapride is an effective drug in at least half of the patients with chronic idiopathic constipation.

Chronic idiopathic constipation: pathophysiology and treatment

Chronic constipation is common in the general population, especially in women, in its idiopathic form. However, confusion still surrounds its definition, despite recent efforts to standardize it. Constipation can be divided in two large subgroups-normal transit and slow transit. The have different pathophysiological bases still not completely understood. Most patients respond to simple therapeutic measures aimed at correcting dietary fiber intake and lifestyle. Others, however, need more aggressive treatment, including laxatives, psychological therapy, and biofeedback. In a few patients with intractable constipation, surgery might be indicated to give relief.

Treatment of intractable constipation in children: experience with cisapride

To establish whether cisapride is beneficial in children with intractable constipation, an open trial was performed. Chronically constipated children who had failed at least 12 weeks of medical therapy received cisapride at a dose of 0.2 mg/kg/dose TID for 12 weeks. Children with pelvic floor dyssynergia were excluded. Patients were followed prospectively for at least 12 months. Thirty children were initially enrolled, and 27 (14 boys, 13 girls) completed the study. At the end of 12 weeks of cisapride treatment, there was a significant increase in the number of bowel movements per week (1.43 +/- 0.52 to 6.48 +/- 4.16; p < 0.05) and significant decreases in the number of accidents per day (2.86 +/- 2.71 to 0.52 +/- 1.23; p < 0.05) and doses of laxatives used per week (14.33 +/- 5.84 to 3.37 +/- 7.10; p < 0.05). Encopresis disappeared in 65.2% of cases (p < 0.0001) and improved in 26%. Sixty-nine percent of the patients stopped using laxatives (p < 0.001). After 12 weeks 18 patients (66.6%) were asymptomatic, seven (25.9%) showed some improvement in bowel movement frequency and number of accidents, and two (7.4%) showed no improvement. The cisapride was well tolerated. After long-term follow-up (20 +/- 9.8 months), 37% of patients had recovered (asymptomatic and off laxatives and cisapride) and 29.6% were still asymptomatic but were using laxatives or cisapride. There were no differences in baseline characteristics between recovered and nonrecovered patients. We conclude that cisapride is effective in the treatment of some children with intractable constipation without pelvic floor dyssynergia.

Cisapride for the treatment of chronic idiopathic constipation

Cisapride appears to be useful as therapy for chronic constipation that is not associated with underlying organic abnormalities or pregnancy and that is refractory to other treatments, such as increased dietary fiber intake or bulk laxatives. Dosages of cisapride that have demonstrated efficacy in chronic constipation range from 5 mg po tid to 20 mg po bid. Treatment for 8-12 weeks may be necessary for an optimal effect to occur. Further studies are needed to evaluate the most effective dosage regimen for the treatment of constipation and to compare the efficacy and cost-efficiency of cisapride with those of conventional therapy. Until these studies are completed, cisapride should not be recommended routinely for patients with constipation. However, it may be a viable option for patients with chronic idiopathic constipation that is refractory to conventional therapy.