Tegaserod: a new 5-HT(4) agonist in the treatment of irritable bowel syndrome

Management of bloating

Abdominal bloating is a subjective sensation of trapped abdominal gas, producing abdominal pressure, fullness sensation, and, in some patients, associated objective abdominal distension. In this month's edition of the journal, a new validated questionnaire to assess the prevalence and impact of gas-related symptoms is presented by Duracinsky et al., showing that gas-related abdominal symptoms are prevalent in patients with irritable bowel syndrome and have a measurable impact on patients daily life. A parallel study by Gardiner et al. assessing the severity of bloating in functional gastrointestinal disorders shows that severe bloating is associated with the severity of abdominal pain, constipation, and somatization, advancing our understanding of the clinical characteristics and relevance of gas-related symptoms in the broad spectrum of functional gastrointestinal disorders. Management of bloating includes non-pharmacological and pharmacological strategies. Dietary interventions to reduce intestinal fermentation and ingestion of food supplements like prebiotics or probiotics can reduce bloating by reducing gas production. The main targets of pharmacological treatments are to improve transit and evacuation with prokinetics, to improve intestinal gas tolerance with antispasmodics and/or neuromodulators, and to modify intestinal microbiota with antibiotics. Secretagogues act by increasing intestinal secretion and decreasing visceral sensitivity and have been reported to be an effective treatment alternative for patients with bloating associated with constipation. Biofeedback therapy addressed to correct abdomino-phrenic dysynergia may be useful for patients with objective abdominal distension, and patients with bloating associated with outlet obstructed defecation may benefit from anorectal biofeedback.

Estrogen and serotonin enhance stress-induced visceral hypersensitivity in female rats by up-regulating brain-derived neurotrophic factor in spinal cord

BACKGROUND

We previously reported that female offspring of dams subjected to chronic prenatal stress (CPS) develop enhanced visceral hypersensitivity (VHS) following exposure to chronic stress in adult life that is mediated by up-regulation of spinal cord BDNF. The aims of this study were to examine the roles of estrogen receptor alpha (ERα) and an increase in spinal serotonin signaling in promoting this enhanced VHS in female rats and up-regulation of spinal cord BDNF transcription.

METHODS

Pregnant dams were exposed to chronic stress from E11 until delivery. At 8 weeks, a chronic adult stress (CAS) protocol was applied for nine days.

KEY RESULTS

Ovariectomy before CAS or treatment with letrozole before and during CAS significantly prevented the development of enhanced VHS in female CPS+CAS rats. Intrathecal application of ERα siRNA significantly reduced VHS, decreased lumbar-sacral spinal cord expression of both ERα and BDNF, and reversed pro-transcriptional epigenetic modifications at BDNF promoter lX. Cerebrospinal fluid serotonin levels and 5HT3A receptor expression in the LS spinal cord were both significantly increased in female CPS+CAS rats. During CAS, intrathecal infusion of alosetron significantly decreased VHS, reduced BDNF and ERα expression in the LS spinal cord, and attenuated RNA pol II and ERα binding to the BNDF core promoter IX.

CONCLUSIONS & INFERENCES

Serotonin-mediated activation of 5HT3A receptors in the spinal cord drives the development of enhanced female-specific VHS in our two hit CPS+CAS through up-regulation of spinal cord ERα.

[Systemic sclerosis and the gastrointestinal tract. Diagnostic and therapeutic approach]

In systemic sclerosis esophagus is affected in 90% followed by anal and rectal involvement (50-70%), stomach (40-70%), colon (10-50%) and small bowel (40%). The main clinical findings are esophagic: dysphagia and sign of gastroesophageal reflux and its complications. Gastric symptomatology is a consequence of gastroparesis (postprandial fullness, nausea). Intestinal affection produces hypomotility (abdominal distention, deficient intestinal absorption, bacterial overgrowth). In colon there are diverticula, intestinal constipation, and fecal incontinence. For the diagnosis of GIT involvement the following are useful: studies of digestive tract with contrast media, endoscopy of upper GIT; gastric emptying; pH metry; esophageal and rectal manometry, as well as test to investigate deficient intestinal absorption syndrome. The prokinetic are a cornerstone for the treatment of hypomotility of GIT, along with pump proton inhibitors for the esophageal alteration and antibiotics for bacterial overgrowth.

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.

Effect of tegaserod on gut transit in male and female subjects

Tegaserod is a novel selective serotonin receptor type-4 (5-HT(4)) partial agonist that stimulates gastrointestinal (GI) motility. Tegaserod has proven efficacy in irritable bowel syndrome with constipation in women and in men and women with chronic idiopathic constipation. The effects on gastric emptying, small bowel transit and colonic transit have not been studied in detail in male and female subjects. This study aimed therefore to assess the effect of gender on GI transit with and without tegaserod. A randomized, placebo-controlled, double-blind, crossover study was performed in 40 healthy subjects (23 males, 17 females). Each treatment period involved three and a half days of bid treatment with either 6 mg tegaserod or an identical placebo. Transit parameters were assessed by a scintigraphy. Tegaserod significantly accelerated gastric emptying, small bowel and colonic transit times (P<0.05-0.0001). The effect was more apparent in male subjects than in females (P=0.044 to P<0.0001). The most striking prokinetic effects were observed in the upper GI tract (stomach and small intestine). In both healthy male and female subjects, tegaserod markedly accelerated small intestinal transit, and induced a significant increase in gastric emptying time and colonic transit. The results imply that tegaserod is a potent prokinetic agent throughout the GI in both sexes.

Recognizing and managing patients with irritable bowel syndrome

PURPOSE

To address the diagnosis and clinical management of irritable bowel syndrome (IBS) and provide a discussion of the available serotonergic agents.

DATA SOURCES

Recent studies examining the pathophysiology of IBS.

CONCLUSIONS

Diagnostic testing may be required in the subset of patients with IBS who present with alarm symptoms, or "red flags," suggestive of underlying organic disease. An important role has been suggested for the neurotransmitter serotonin in both gut motility and visceral pain sensitivity.

IMPLICATIONS FOR PRACTICE

A diagnosis of IBS is largely based on symptoms; therefore, effective clinician-patient communication and careful attention to details of patient presentation, history, and physical examination are essential.

Severe gastrointestinal involvement in systemic sclerosis: report of five cases and review of the literature

OBJECTIVE

To review current literature on the gastrointestinal tract (GIT) manifestations of systemic sclerosis (SSc) and to report on 5 patients with severe gastrointestinal SSc.

MATERIALS AND METHODS

The clinical course and histopathology of 5 patients are described. A review of the medical literature registered in MedLine and PreMedLine databases from 1996 through mid-2004 was performed using the keywords systemic sclerosis and scleroderma and combining them with text words such as gastric, gastrointestinal, anorectal, colonic, and hepatic.

RESULTS

All 5 patients had severe GIT involvement: 4 with diffuse cutaneous SSc (dcSSc) and 1 with limited cutaneous SSc (lcSSc). Autopsy results of 2 patients who died from severe malnutrition and aspiration pneumonia are presented. Literature review includes involvement from oral cavity to anus with varying degrees of severity. Most GIT manifestations result from dysmotility secondary to infiltration of the gastrointestinal wall with fibrous tissue and can cause life-threatening malabsorption and malnutrition. Diagnostic tests, pathology, and treatments of GIT SSc are reviewed.

CONCLUSIONS

GIT involvement in SSc can be severely debilitating and even life-threatening. Although morbidity is inevitable, appropriate supportive treatment can prolong survival.

RELEVANCE

GI complications of SSc cause significant morbidity and mortality.

Chronic constipation in children: organic disorders are a major cause

Diagnostic tools for paediatric chronic constipation have been limited, leading to over 90% of patients with treatment-resistant constipation being diagnosed with chronic idiopathic constipation, with no discernible organic cause. Work in our institution suggests that a number of children with intractable symptoms actually have slow colonic transit leading to slow transit constipation. This paper reviews recent data suggesting that a significant number of the children with chronic treatment-resistant constipation may have organic causes (slow colonic transit and outlet obstruction) and suggests new approaches to the management of children with chronic treatment-resistant constipation.

A double-blind, placebo-controlled, randomized study to evaluate the efficacy, safety and tolerability of tegaserod in patients with irritable bowel syndrome

BACKGROUND

Tegaserod has been shown to be an effective therapy for the multiple symptoms of irritable bowel syndrome (IBS) in Western and Asia-Pacific populations. This study evaluated the efficacy, safety and tolerability of tegaserod versus placebo in patients with IBS.

METHODS

Patients with IBS (excluding those whose primary bowel symptom was diarrhoea) were randomized to receive either tegaserod 6 mg b.i.d. (n = 327) or placebo (n = 320) for a 12-week double-blind treatment period. The primary efficacy variable (over weeks 1 to 4) was the response to the question: 'Over the past week do you consider that you have had satisfactory relief from your IBS symptoms?' Secondary efficacy variables assessed overall satisfactory relief over 12 weeks and the individual IBS symptoms.

RESULTS

Overall satisfactory relief was greater in the tegaserod group than in the placebo group. Over weeks I to 4, the odds ratio was 1.54, that is, the odds of satisfactory relief were 54% higher in the tegaserod group than in the placebo group (95% confidence interval for odds ratio (CI) (1.14, 2.08), P = 0.0049). Over weeks 1 to 12, the odds ratio was 1.78, that is, the odds of satisfactory relief were 78% higher in the tegaserod group than in the placebo group (95% CI (1.35, 2.34), P < 0.0001). A statistically significant therapeutic gain over placebo was observed for the majority of weeks from week 1 to week 12 (except weeks I and 4), with a mean therapeutic gain of 7.3 and 10.6 percentage points over weeks 1-4 and weeks 1-12, respectively. Headache was the most commonly reported adverse event (8.0% tegaserod versus 4.7% placebo). Diarrhoea was reported by 9.2% of patients on tegaserod (1.3% on placebo) and led to discontinuation in 2.8% of tegaserod patients.

CONCLUSION

Tegaserod 6 mg b.i.d. is an effective, safe and well-tolerated treatment in patients suffering from IBS without diarrhoea as primary bowel symptom.

Benefit-Risk Assessment of Tegaserod in Irritable Bowel Syndrome

Tegaserod is a new partial agonist of serotonin 5-HT4 receptors specifically developed for the treatment of nondiarrhoeal forms of irritable bowel syndrome (IBS). Among its various effects is the stimulation of the peristaltic reflex with its promotility action appearing to affect the whole length of the gastrointestinal tract. Tegaserod has been assessed in a number of international multicentre trials and its use leads to an improvement in abdominal pain and bowel dysfunction as well as global well-being, at the expense of remarkably few adverse effects. It is noteworthy that it also appears to improve bloating, a benefit that has not been previously reported for a medication used in IBS. The optimal dose is 6 mg twice daily and the advantage of tegaserod over placebo in different trials varies from 5-20% with the number needed to treat ranging from 5-15 depending on the time at which this effect is calculated during the course of a trial. Recent experience with other drugs acting on 5-HT receptors has focused attention on possible safety issues such as prolongation of the QTc interval on the electrocardiogram and ischaemic colitis. However, data from efficacy trials and studies specifically designed to address the safety of tegaserod have not revealed any evidence of cardiotoxicity or the potential for causing ischaemic colitis. Furthermore, investigation of possible interactions with other drugs such as warfarin or the oral contraceptive have not resulted in any prescribing restrictions. Inappropriate prescription of tegaserod to a subgroup of IBS patients for which the drug was not designed, does not appear to have any serious consequences. Most of the efficacy data on tegaserod has been accumulated in females, simply as a result of the failure to recruit adequate numbers of males or restriction of trials to females. There is therefore insufficient information to assess whether there might be any potential gender differences in responsiveness. For this reason, the drug is currently only licensed for use in females.