The symptomatic effect of cisapride in patients with irritable bowel syndrome and constipation

Tegaserod for the Treatment of Irritable Bowel Syndrome

Background: Tegaserod (Zelnorm®) is a 5-hydroxytryptamine (serotonin) type 4 receptor agonist for the treatment of hypomotility disorders of the lower gastrointestinal tract associated with the irritable bowel syndrome with constipation (IBS-C).

Objective: The authors provide the reader with a better understanding on tegaserod mechanism of action, on its pharmacodynamics and pharmacokinetic properties, on safety and tolerability, with a summary of the key published clinical trials conducted in patients with irritable bowel syndrome (IBS). Its effects on colon inflammation have also been described.

Results: Tegaserod was withdrawn in 2007 due to increased risks of cardiovascular adverse effects. The manufacturer denied this, because pre-existing cardiovascular disease or risk factors were attributed to all affected patients. Thus, no causal relationship between tegaserod use and cardiovascular events was clearly shown. A matched case-control study of tegaserod-treated with untreated patients found no association between tegaserod and adverse cardiovascular outcomes. Despite its adverse effects, tegaserod resulted to be effective in treating chronic constipation in adult women aged < 65 years with IBS-C, while the safety and effectiveness of tegaserod in men with IBS-C have not been established.

Conclusion: Tegaserod was resubmitted to the Food and Drug Administration in 2018 for use in a low-risk population. Moreover, tegaserod has also been shown to improve symptoms, enhance gastric accommodation and significantly attenuate visceral pain arising from the colon in functional dyspepsia patients. Treatment with tegaserod seems also to exert a protective effect in inflamed colons, reducing the severity of colitis in animal models.

Mixed 5-HT3 antagonists/5-HT4 agonists for irritable bowel syndrome: a systematic review

AIM: To systematically review the evidence for the efficacy and safety of mixed 5-HT₃ antagonists/5-HT₄ agonists in the treatment of irritable bowel syndrome (IBS).

METHODS: According to the recommendations of the Cochrane Collaboration, a meta-analysis was conducted on 2 841 patients from eight eligible trials with respect to the usage of these drugs.

RESULTS: The unimprovement in IBS global symptoms [42.7% vs 46.9%, RR = 0.91, 95% CI (0.58, 1.43)], abdominal pain [53.2% vs 59.3%, RR = 0.90, 95% CI (0.72, 1.11)] or constipation [54.0% vs 58.5%, RR = 0.91, 95%CI (0.74, 1.12)] did not differ significantly in the presence of cisapride vs placebo. In the presence of renzapride, lower doses (1 mg/d and 2 mg/d) were found not to be superior to placebo in attenuating global symptoms [RR = 0.95, 95% CI (0.67, 1.35); RR = 0.79, 95% CI (0.67, 1.17)]; however, high dose of renzapride (4 mg/d) resulted in a significant difference [67.8 % vs 73.9%, RR = 0.91, 95% CI (0.86, 0.96)]. There was no significant difference in the incidence of adverse events among cisapride [RR = 1.52, 95% CI (0.58, 3.99)], renzapride [RR = 1.11, 95% CI (0.98, 1.24)] and placebo.

CONCLUSION: Except for high dose of renzapride (4 mg/d) which could relieve the global symptoms in IBS-C patients, there was no sufficient evidence to indicate that low dose renzapride or cisapride might be used to improve the global symptoms, abdominal pain as well as constipation discomfort.

Review article: the treatment of functional abdominal bloating and distension

BACKGROUND

Abdominal bloating and distension are common symptoms in patients with functional gastrointestinal disorders (FGIDs), however, relatively little is known about their treatment.

AIM

To review the treatment trials for abdominal bloating and distension.

METHODS

A literature review in Medline for English-language publications through February 2010 of randomised, controlled treatment trials in adults. Study quality was assessed according to Jadad's score.

RESULTS

Of the 89 studies reviewed, 18% evaluated patients with functional dyspepsia, 61% with irritable bowel syndrome (IBS), 10% with chronic constipation and 10% with other FGIDs. No studies were conducted in patients diagnosed with functional abdominal bloating. The majority of trials investigated the efficacy of prokinetics or probiotics, although studies are heterogeneous with respect to diagnostic criteria and outcome measures. In general, bloating and/or distension were evaluated as secondary endpoints or as individual symptoms as part of a composite score rather than as primary endpoints. A greater proportion of IBS patients with constipation reported improvement in bloating with tegaserod vs. placebo (51% vs. 40%, P<0.0001) and lubiprostone (P<0.001). A greater proportion of nonconstipating IBS patients reported adequate relief of bloating with rifaximin vs. placebo (40% vs. 30%, P<0.001). Bloating was significantly reduced with the probiotics, Bifidobacterium infantis 35624 (1×10(8) dose vs. placebo: -0.71 vs. -0.44, P<0.05) and B. animalis (live vs. heat-killed: -0.56±1.01 vs. -0.31±0.87, P=0.03).

CONCLUSIONS

Prokinetics, lubiprostone, antibiotics and probiotics demonstrate efficacy for the treatment of bloating and/or distension in certain FGIDs, but other agents have either not been studied adequately or have shown conflicting results.

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.

Meta-analysis: factors affecting placebo response rate in the irritable bowel syndrome

BACKGROUND

Irritable bowel syndrome (IBS) is a functional disorder of the gastrointestinal tract with a significant placebo response.

AIM

To conduct a systematic review and meta-analysis examining the magnitude of placebo response rate in treatment trials for IBS.

METHODS

MEDLINE, EMBASE and the Cochrane central register of controlled trials were searched to identify randomized controlled trials (RCTs) comparing pharmacological therapies with placebo in adult IBS patients. Studies reported either global assessment of IBS symptom cure or improvement or abdominal pain cure or improvement. Data were extracted as intention-to-treat analyses with drop-outs assumed to be treatment failures and pooled using a random-effects model. Proportion of placebo patients experiencing symptom improvement or resolution was reported with a 95% confidence interval (CI). Effect of trial characteristics on magnitude of placebo response was examined.

RESULTS

In all, 73 RCTs were eligible, including 8364 patients with IBS allocated to placebo. Pooled placebo response rate across all RCTs was 37.5% (95% CI 34.4-40.6%). Rates were higher in European RCTs, RCTs that used physician-reported outcomes and RCTs using shorter duration of therapy.

CONCLUSIONS

Placebo response rates across RCTs of pharmacological therapies in IBS were high. Future research should identify patient characteristics predicting placebo response.

Efficacy of 5-HT3 antagonists and 5-HT4 agonists in irritable bowel syndrome: systematic review and meta-analysis

OBJECTIVES

Irritable bowel syndrome (IBS) is a chronic functional disorder. 5-Hydroxytryptamine (5-HT) is a key modulator of gastrointestinal sensorimotor function. Many patients have IBS that can be difficult to treat, which has led to the development of newer agents, such as 5-HT(3) antagonists and 5-HT(4) agonists. We conducted a systematic review and meta-analysis of randomized controlled trials (RCTs) to estimate the efficacy of all available 5-HT agents in IBS.

METHODS

MEDLINE, EMBASE, and the Cochrane Controlled Trials Register were searched (up to June 2008). Trials recruiting adults with IBS in primary, secondary, or tertiary care comparing 5-HT(3) antagonists or 5-HT(4) agonists with placebo were eligible. Dichotomous symptom data were pooled to obtain a relative risk (RR) of remaining symptomatic after therapy, with a 95% confidence interval (CI). The number needed to treat (NNT) was calculated from the reciprocal of the risk difference.

RESULTS

The strategic search identified 1,593 citations. A total of 29 RCTs were eligible for inclusion; placebo was compared with 5-HT(3) antagonists in 11 RCTs, with tegaserod in 11, and with mixed 5-HT(3) antagonists/5-HT(4) agonists in 7. The study quality was generally high. The RR of IBS symptoms persisting with 5-HT(3) antagonists vs. placebo was 0.78 (95% CI: 0.71-0.86), with a similar benefit for both alosetron and cilansetron. Tegaserod was also superior to placebo (RR=0.85; 95% CI: 0.80-0.90). Renzapride and cisapride had no benefit in IBS.

CONCLUSIONS

Alosetron, cilansetron, and tegaserod are all effective in the treatment of IBS. Serious adverse events were rare in the eligible RCTs included in this systematic review.

Development and psychometric testing of the Visual Analogue Scale for Irritable Bowel Syndrome (VAS-IBS)

BACKGROUND

The aim of this study was to develop and psychometrically test a short, patient-reported questionnaire to be used in clinical practice for patients with Irritable Bowel Syndrome (IBS). The Visual Analogue Scale for Irritable Bowel Syndrome (VAS-IBS) questionnaire was designed to measure the treatment response of symptoms and well-being in patients suffering from IBS.

METHODS

The VAS-IBS was psychometrically tested for content and criterion validity, scale acceptability, item-reduction, internal reliability consistency, simplicity, and speed. Two samples were used. One expert panel (five physicians and four registered nurses), who gave their opinion on the content validity, and one of 71 patients with IBS (mean age 38 years SD +13, range 19-65), who completed the VAS-IBS, as well as the Gastrointestinal Symptom Rating Scale and the Psychological General Well-Being Index for criterion validity.

RESULTS

The items in the VAS-IBS capture the main physical concerns women with IBS might present and the psychometric testing confirmed that the VAS-IBS is an acceptable homogeneous patient-reported questionnaire indicated by Cronbach's alpha internal consistency reliability coefficient, with a value of 0.85. All correlations to test the criterion validity performed by using Pearson's correlation test, were statistically significant (p < 0.0001) and in the expected directions. The VAS-IBS is easy to complete and unproblematic to calculate.

CONCLUSION

The VAS-IBS appears to be reliable and user-friendly, for patients as well as for health professionals. The final version of the VAS-IBS including nine items needs to be further tested in clinical practice cross-culturally in women as well as in men.

Systematic review: the efficacy of treatments for irritable bowel syndrome--a European perspective

BACKGROUND

Irritable bowel syndrome (IBS) is a common, chronic disorder, characterized by abdominal pain/discomfort, bloating and altered bowel habit.

AIM

To conduct a systematic evidence-based review of pharmacological therapies currently used, or in clinical development, for the treatment of IBS in Europe. The safety and tolerability of these therapies are the subject of an accompanying review.

METHODS

A literature search was completed for randomized controlled studies which included adult patients with IBS and an active or placebo control, assessed IBS symptoms, and were published in English between January 1980 and June 2005. The level of evidence for efficacy was graded according to the quality of the trial design and the study outcome.

RESULTS

There is some evidence for improvement of individual IBS symptoms with antidiarrhoeals (diarrhoea), antispasmodics (abdominal pain/discomfort), bulking agents (constipation), tricyclic antidepressants (abdominal pain/discomfort) and behavioural therapy. In contrast, there is strong evidence for the improvement of global IBS symptoms with two new serotonergic agents: the 5-HT4 selective agonist tegaserod (IBS with constipation) and the 5-HT3 antagonist alosetron (IBS with diarrhoea). Further data are required for the 5-HT3 antagonist, cilansetron, and the mixed 5-HT3 antagonist/5-HT4 agonist renzapride before their utility in IBS can be appraised.

CONCLUSIONS

There is limited evidence for the efficacy, safety and tolerability of therapies currently available in Europe for the treatment of IBS. Overall, there is an absence of pharmacological agents licensed specifically for the treatment of IBS subtypes, and new agents are awaited in Europe that will allow changes in clinical practice to focus on and improve global IBS symptoms.

Systematic review: the safety and tolerability of pharmacological agents for treatment of irritable bowel syndrome--a European perspective

AIM

To use an evidence-based approach to evaluate the safety and tolerability of the treatments available for irritable bowel syndrome (IBS), or in clinical development, in Europe. A separate review appraises the evidence for the efficacy of these therapies.

METHODS

A literature search (for 1980 to 2005) was completed for all relevant clinical trial data and other articles which included safety information on the use of pharmacological IBS therapies. Clinical trials were scored according to the level of safety information, and adverse event incidence reported when possible.

RESULTS

The tolerability of many of the agents used to treat IBS in Europe is poorly understood. However, serotonergic agents, such as tegaserod and alosetron, which are currently unavailable in Europe, have undergone rigorous assessment in IBS and their benefits have been established. Following initial marketing of alosetron for use in patients with IBS with diarrhoea, concerns about severe constipation and ischaemic colitis resulted in restriction of its use to women with severe IBS symptoms. This highlights the importance of post-marketing surveillance and post-marketing studies in refining the therapeutic indication of new IBS therapies, which will help to identify appropriate recipients for the drug and establish the impact of adverse reactions in clinical practice.

CONCLUSIONS

There is a significant lack of data on the safety and tolerability of the therapies currently used routinely to treat IBS in Europe. The newer agents have undergone rigorous assessment, such that their benefits and risks in treating IBS are established. Defining their place among the spectrum of available therapies remains challenging when the benefits and risks of the older treatments are so poorly characterized.

Herbal medicines for treatment of irritable bowel syndrome

BACKGROUND

Traditional herbal therapies have been used for a long time to treat gastrointestinal disorders including irritable bowel syndrome, and their effectiveness from clinical research evidence needs to be systematically reviewed.

OBJECTIVES

To assess the effectiveness and safety of herbal medicines in patients with irritable bowel syndrome.

SEARCH STRATEGY

We searched the following electronic databases till July 2004: The Cochrane Library (CENTRAL), MEDLINE, EMBASE, AMED, LILACS, the Chinese Biomedical Database, combined with hand searches of Chinese journals and conference proceedings till end of 2003. No language restriction was used.

SELECTION CRITERIA

Randomised controlled trials of herbal medicines compared with no treatment, placebo, pharmacological interventions were included.

DATA COLLECTION AND ANALYSIS

Data were extracted independently by two authors. The methodological quality of trials was evaluated using the components of randomisation, allocation concealment, double blinding, and inclusion of randomised participants.

MAIN RESULTS

Seventy-five randomised trials, involving 7957 participants with irritable bowel syndrome, met the inclusion criteria. The methodological quality of three double-blind, placebo-controlled trials was high, but the quality of remaining trials was generally low. Seventy-one different herbal medicines were tested in the included trials, in which herbal medicines were compared with placebo or conventional pharmacologic therapy. Herbal medicines were also combined with conventional therapy and compared to conventional therapy alone.Compared with placebo, a Standard Chinese herbal formula, individualised Chinese herbal medicine, STW 5 and STW 5-II, Tibetan herbal medicine Padma Lax, traditional Chinese formula Tongxie Yaofang, and Ayurvedic preparation showed significantly improvement of global symptoms. Compared with conventional therapy in 65 trials testing 51 different herbal medicines, 22 herbal medicines demonstrated a statistically significant benefit for symptom improvement, and 29 herbal medicines were not significantly different than conventional therapy. In nine trials that evaluated herbal medicine combined with conventional therapy, six tested herbal preparations showed additional benefit from the combination therapy compared with conventional monotherapy. No serious adverse events from the herbal medicines were reported.

AUTHORS' CONCLUSIONS

Some herbal medicines may improve the symptoms of irritable bowel syndrome. However, positive findings from less rigorous trials should be interpreted with caution due to inadequate methodology, small sample sizes, and lack of confirming data. Some herbal medicines deserve further examination in high-quality trials.

The placebo effect in irritable bowel syndrome trials: a meta-analysis

BACKGROUND

Despite the apparent high placebo response rate in randomized placebo-controlled trials (RCT) of patients with irritable bowel syndrome (IBS), little is known about the variability and predictors of this response.

OBJECTIVES

To describe the magnitude of response in placebo arms of IBS clinical trials and to identify which factors predict the variability of the placebo response.

METHODS

We performed a meta-analysis of published, English language, RCT with 20 or more IBS patients who were treated for at least 2 weeks. This analysis is limited to studies that assessed global response (improvement in overall symptoms). The variables considered as potential placebo modifiers were study design, study duration, use of a run-in phase, Jadad score, entry criteria, number of office visits, number of office visits/study duration, use of diagnostic testing, gender, age and type of medication studied.

FINDINGS

Forty-five placebo-controlled RCTs met the inclusion criteria. The placebo response ranged from 16.0 to 71.4% with a population-weighted average of 40.2%, 95% CI (35.9-44.4). Significant associations with lower placebo response rates were fulfillment of the Rome criteria for study entry (P=0.049) and an increased number of office visits (P=0.026).

CONCLUSIONS

Placebo effects in IBS clinical trials measuring a global outcome are highly variable. Entry criteria and number of office visits are significant predictors of the placebo response. More stringent entry criteria and an increased number of office visits appear to independently decrease the placebo response.

Treatments targeting putative mechanisms in irritable bowel syndrome

The pathophysiology of irritable bowel syndrome (IBS) is heterogeneous; it is possible for several mechanisms to be disturbed in the same patient. Isolating a single target for pharmacological manipulation is also difficult because of the complexity and overlap of the neural circuitry in the enteric and central nervous system. This review summarizes the rationale and efficacy of current and future therapies for IBS, on the basis of putative pathophysiological models. The modulation of gastrointestinal sensorimotor function, intestinal gas handling, the gastrocolonic reflex, neurohormonal stress responses, central processing of afferent information, and microbial flora are the current frontiers for experimental therapeutics for IBS. Patients presumed to have POSTINFECTIOUS IBS have also been targeted as a distinct group. In the very near future, it is unlikely that a single drug will come to the fore as a suitable and successful treatment for everyone with IBS, but new data on potential therapeutic targets lend hope for the improved long-term management of IBS. Disease modification rather than just symptom-based treatments must remain the goal.

Meta-analysis: The treatment of irritable bowel syndrome

To evaluate therapies available for the treatment of irritable bowel syndrome, and provide consensus recommendations for their use, a total of 51 double-blind clinical trials using bulking agents, prokinetics, antispasmodics, alosetron, tegaserod and antidepressants were selected. The quality of studies was assessed using 5-point scale. Meta-analyses were performed on all studies, and on 'high-quality studies'. The efficacy of fibre in the global irritable bowel syndrome symptoms relief (OR: 1.9; 95% CI:1.5-2.4) was lost after exclusion of low-quality trials (OR: 1.4; 95% CI: 1.0-2.0, P = 0.06). When excluding the low-quality trials, an improvement of global irritable bowel syndrome symptoms with all antispasmodics (OR: 2.1; 95% CI:1.8-2.9) was maintained only for octylonium bromide, but on the basis of only two studies. Antidepressants were effective (OR: 2.6, 95% CI: 1.9-3.5), even after exclusion of low-quality studies (OR: 1.9, 95% CI: 1.3-2.7). Alosetron (OR: 2.2; 95% CI: 1.9-2.6) and tegaserod (OR: 1.4; 95% CI: 1.2-1.5) showed a significant effect in women. We recommend the use of tegaserod for women with irritable bowel syndrome with constipation and alosetron for women with severe irritable bowel syndrome with diarrhoea. Antidepressants can be beneficial for irritable bowel syndrome with diarrhoea patients with severe symptoms. Loperamide can be recommended in painless diarrhoea. Evidence is weak to recommend the use of bulking agents in the treatment of irritable bowel syndrome with constipation.

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.

Cisapride treatment of constipation-predominant irritable bowel syndrome is not superior to placebo

BACKGROUND AND AIM

Previous studies with cisapride reported conflicting results in patients with constipation-predominant irritable bowel syndrome (IBS). To gain further evidence, this randomized double-blind study was carried out.

METHODS

Eighty-two symptomatic outpatients were randomized to receive either 5 mg oral cisapride or placebo three times daily for a period of 12 weeks. In patients without satisfactory improvement after 4 weeks, the dose was doubled. Symptom evaluation used visual analog scales (VAS) and the investigators' global assessment.

RESULTS

After 4 weeks, in 18 (45%) cisapride and 24 (57%) placebo patients the dose was doubled because of insufficient improvement of symptoms. The mean VAS score for patients' global rating of IBS symptoms at baseline was 67.5 mm for cisapride versus 70.7 mm for placebo, and improved to 38.4 mm versus 44.5 mm after 12 weeks of treatment. Investigators rated the overall effect of therapy as good or excellent in 70% of the cisapride and 50% of the placebo group. Neither these nor further efficacy parameter differences reached statistical significance.

CONCLUSIONS

These results indicate that the effect of 15-30 mg cisapride daily on symptoms of constipation-predominant IBS is not significantly superior to placebo. During the 12 week treatment of this trial cisapride proved to be safe and tolerable.

Update in the pharmaceutical therapy of the irritable bowel syndrome

The therapeutic management of the irritable bowel syndrome (IBS) is ineffective and not satisfying either patients or practitioners. Research in functions of the enteric nervous system and its interaction with the central nervous system is the basis for the development of emerging pharmaceuticals in therapy of the IBS. These pharmaceuticals include agents such as opioid agonists, psychotropic agents and particularly serotonin receptor modulators. These novel pharmaceuticals aim to provide a more comprehensive approach in the therapy of the IBS and will serve both patients and practitioners. So far, the US Food and Drug Administration has approved two agents specifically for the treatment of the IBS, both belonging to the group of serotonin receptor modulators. However, questions remain whether a single therapy is sufficient in the management of IBS because this disease is influenced by biological and psychological as well as cultural and social factors.

Medical management of fecal incontinence

Diarrhea and constipation are known risk factors for fecal incontinence. This report reviews how to diagnose and medically treat patients with chronic diarrhea, chronic constipation with overflow incontinence, and incontinence resulting from rectal mucosal prolapse secondary to hemorrhoids. Antidiarrheal agents (including loperamide, diphenoxylate, and difenoxin) and the tricyclic antidepressant amitriptyline improve continence in patients with diarrhea-associated incontinence. Other antidiarrheal agents are under investigation. The mechanism is believed to be decreased intestinal motility and stool frequency resulting in more formed stools. Increases in anal canal resting pressure may also contribute to improvement in continence. Adverse effects are constipation from excessive use. In addition to antidiarrheal drugs, fiber supplements may improve incontinence associated with diarrhea. Transient, benign cases of constipation usually respond to increasing fluid intake and dietary fiber, improving mobility, or eliminating the concurrent use of constipating drugs. For mild to moderate constipation, bulking agents, laxatives, and stool softeners are used cautiously so as not to excessively loosen stools and exacerbate anal incontinence. Laxatives have been shown to improve continence, possibly through the mechanism of eliminating fecal impaction. Prolapsing hemorrhoids may partially obstruct defecation and cause soilage from the passage of fecal material, mucus, or blood. With endoscopic banding, a ligator is attached to an endoscope and a tight band is placed around the enlarged vein, causing the hemorrhoid to thrombose.

Pharmacologic therapy for the irritable bowel syndrome

The management of the irritable bowel syndrome (IBS) remains unsatisfactory. For abdominal pain, antispasmodics are, at best, of only modest efficacy. Tricyclic antidepressants in low dose are useful (with the number needed to treat being three), but side effects and patient concerns regarding use of a centrally acting agent for depression remain limitations. Selective serotonin reuptake inhibitors are of uncertain efficacy in IBS. Opioid agonists, especially loperamide, are useful for diarrhea but not for pain in IBS; rebound constipation also remains a problem. Bile salt sequestering agents are not of established value in IBS but seem to be useful clinically in a small group of IBS patients with diarrhea. Aloestron, a 5HT(3) antagonist, should be reserved, if available, for women with severe diarrhea predominant IBS who have failed to respond to conventional therapy, and started at a low dose. Fiber and bulking agents may help constipation in some trials, but the evidence that they are efficacious in IBS is equivocal; they are frequently prescribed as first-line drugs for IBS regardless of the primary bowel disturbance but often increase bloating, gas, and pain. Laxatives are not of established value in IBS but are often taken by patients with constipation predominant IBS. Tegaserod, a partial 5HT(4) agonist, is now available in the United States and other countries for use in women with IBS whose primary bowel symptom is constipation; its efficacy in men and in those with alternating bowel habits is unknown. Probiotics are of uncertain efficacy. Chinese herbal medicine data are insufficient. Other new drugs in development include the cholecystokinin antagonists and novel visceral analgesics. Both current and potential therapies for IBS are reviewed in this article.

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

Tegaserod is a selective partial agonist acting on serotonergic type 4 receptors (5-HT(4)). Pharmacodynamic studies indicate that tegaserod is able to stimulate gut propulsion and secretion with a net prokinetic effect. In contrast to other 5-HT(4) agonists endowed with a complex pharmacological profile, tegaserod has a reliable prokinetic activity in the colon. Clinical trials show that tegaserod is effective and safe in the treatment of patients with irritable bowel syndrome. In particular, tegaserod relieves symptoms of abdominal pain, discomfort, abdominal bloating and constipation.

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.

Irritable bowel syndrome neuropharmacology. A review of approved and investigational compounds

Anticholinergics and prokinetics are mainstays of therapy for Irritable Bowel Syndrome (IBS) patients despite their limited efficacy and troublesome side-effect profile. The clinical limitations of these drugs are a result of their relative broad and nonspecific pharmacologic interaction with various receptors. Recent advances in gut physiology have led to the identification of various receptor targets that may play a pivotal role in the pathogenesis of IBS. Medicinal chemists searching for safe and effective IBS therapies are now developing compounds targeting many of these specific receptors. The latest generation of anticholinergics, such as zamifenacin, darifenacin, and YM-905, provide selective antagonism of the muscarinic type-3 receptor. Tegaserod, a selective 5-HT4 partial agonist, tested in multiple clinical trials, is effective in reducing the symptoms of abdominal pain, bloating, and constipation. Ezlopitant and nepadudant, selective antagonists for neurokinin receptors type 1 and type 2, respectively, show promise in reducing gut motility and pain. Loperamide, a mu (mu) opioid receptor agonist, is safe and effective for IBS patients with diarrhea (IBS-D) as the predominant bowel syndrome. Fedotozine, a kappa (kappa) opioid receptor agonist, has been tried as a visccral analgesic in various clinical trials with conflicting results. Alosetron, a 5-HT3 receptor antagonist, has demonstrated efficacy in IBS-D patients but incidents of ischemic colitis seen in post-marketing follow-up resulted its removal from the market. Compounds that target cholecystokinin. A, N-methyl-D-aspartate, alpha 2-adrenergic, and corticotropin-releasing factor receptors are also examined in this review.

Update in the therapeutic management of irritable bowel syndrome

Irritable bowel syndrome (IBS) is a remarkably frequent disorder that leads to relevant impairment in patients' quality of life. Four mechanisms are involved in the pathogenesis of IBS: altered intestinal motility; increased visceral sensitivity; disturbed intestinal reflexes (intrinsic and extrinsic), and psychological disorders. The close relationship between the central nervous system and the enteric nervous system (the brain-gut axis) is the basis of the actual research on IBS therapy. It is conceivable that in the near future a better understanding of IBS pathophysiology will help us to tailor treatment for different IBS patients. At the moment, the subclassification of the diverse patterns of symptomatology allows the adjustment of treatments for IBS according to the clinical predominance of each patient. Dietary modifications like fiber supplementation, antidiarrheal agents and antispasmodic drugs are the basis of the current treatment of IBS and depend on the predominant symptom (constipation, diarrhea or pain, respectively). If severe pain is present, antidepressant agents are an appropriate alternative. However, the scientific evidence supporting this current therapeutic approach is limited. Visceral analgesics and serotonin agonists and antagonists may play an important therapeutic role in the near future. However, it is not likely that one single treatment will help every IBS patient and many of them will need a more complex approach with multidisciplinary therapy (diet, psychotherapy, medications).

Irritable bowel syndrome: update on pathogenesis and management

Irritable bowel syndrome (IBS) comprises a major proportion of gastrointestinal and primary care practice worldwide. The past several years have seen the rapid evolution of a new and comprehensive model of IBS based on alterations in brain-gut interactions. Alterations in the bidirectional communication between the enteric nervous system and the central nervous system are implicated in the pathogenesis of IBS. 5-Hydroxytryptamine (5-HT; serotonin), a major neurotransmitter in the gastrointestinal tract, and its receptors 5-HT3 and 5-HT4 are involved in the control of gastrointestinal function. A number of abnormal motor and sensory patterns have been reported in patients with IBS. However, it is not known whether these abnormalities are related to symptoms or have a role in establishing a diagnosis of functional gastrointestinal disorders. Visceral hyperalgesia in IBS patients can be secondary to altered receptor sensitivity at the viscus itself and altered central modulation of sensation involving psychological influences in the interpretation of these sensations. The development of diagnostic criteria for IBS helps to avoid unnecessary and costly investigations. A detailed history allows us to diagnose IBS and search for another cause if warning symptoms are present. The Rome criteria are presently used to define IBS and are currently the most widely applied criteria used in clinical diagnosis and research purposes. Abdominal pain or discomfort associated with chronic altered bowel habits are the mainstay in diagnosis, while the supportive criteria may be used to further classify IBS patients into diarrhea-predominant or constipation-predominant subgroups. Minimal diagnostic tests have been advocated in the initial diagnostic approach to patients with suspected IBS, depending on the predominant symptom. The therapeutic goals in IBS must focus on the overall well-being of the patient, including abdominal symptoms and the accompanying nonbowel symptoms and affective disorders. It is important to establish an effective physician-patient relationship and to reassure the patient once the diagnosis of IBS is made. Dietary modification may be of value in some patients with IBS. Dietary fiber is frequently recommended for patients with constipation-predominant IBS. Two novel serotonin agonists are currently under development for constipated IBS patients, tegaserod and prucalopride. Antidiarrheal agents, including loperamide and diphenoxylate, may help patients with diarrhea-predominant IBS. 5-HT3 receptor antagonists may play a role in the management of such patients in the future. Psychological treatment and antidepressants should be considered when IBS symptoms are severe or refractory or associated with psychological distress and impaired quality of life.

Serotoninergic neuroenteric modulators

Irritable bowel syndrome (IBS) is common and can be disabling. Several drugs that modulate serotonin (5HT) and other neurotransmitters in the gut (neuroenteric modulators) have either become available or are in development, but progress has been slowed by toxicity. Blockade of 5HT(3) receptors slows colonic transit, increases fluid absorption and increases left colon compliance. Alosetron, a potent 5HT(3) receptor antagonist, has, in women but not in men, a clinically significant but modest therapeutic gain over placebo in the relief of abdominal pain and discomfort and bowel-habit disturbance (but not bloating) in diarrhoea-predominant IBS. However, the drug unexpectedly was associated with ischaemic colitis and, very rarely, severe constipation-induced complications, and alosetron has been withdrawn. Cilansetron may have similar efficacy in men and women. 5HT(4) receptor stimulation results in accelerated colonic transit, and tegaserod, a partial 5HT(4) receptor agonist, has modest but clinically significant advantage over placebo in constipation-predominant IBS; the benefit seems to be confined to females. Long-term published data are lacking and safety concerns have been raised. Prucalopride, a full 5HT(4) agonist that has been promising in idiopathic chronic constipation, may also be limited by toxicity. Other 5HT receptor antagonists and agonists are under development for IBS. However, for modulators of single receptors to achieve a substantial therapeutic gain, and to do so safely, drug targets based on the pathophysiology of IBS need to be better defined.

Drug treatment options for irritable bowel syndrome: managing for success

Irritable bowel syndrome (IBS) is a functional gut disorder the diagnosis of which is based on clinical symptoms as set forth by the Rome criteria. As the population ages, especially with the population of patients >75 years of age expanding greatly over the next 10 years, IBS is becoming one of the most common diseases of the elderly. Thus far, developing treatment strategies for patients with IBS has been difficult because of the lack of pharmacological targets and the wide range of symptomatology. Additionally, demonstration of a therapeutic benefit is difficult in the presence of a high placebo response observed regardless of the therapy employed. Fibre, antidiarrhoeals and antispasmodics all play some role in the symptomatic treatment of IBS. With the evolution of IBS as a disorder of visceral hypersensitivity, new drugs have been developed that target the enteric nervous system. Tricyclic antidepressants (TCAs) have been found to target the enteric neurons and play a role in pain modulation. Currently, the TCAs are recommended only for severe cases of IBS pain. The newest class of drugs to be approved for use in IBS are the serotonin (5-hydroxytryptamine; 5-HT) antagonists. Specifically, the 5-HT3 receptor antagonists have been shown to decrease symptoms in female patients with IBS. A related class of drugs, the 5-HT4 receptor agonists, is being developed for the treatment of constipation-predominant IBS. Further investigation into the role of spinal afferent neurons in visceral hypersensitivity is at the forefront of IBS research. Several experimental drug therapies for IBS are also discussed in this review including N-methyl-D-aspartate receptor antagonists, neurokinin-1 receptor antagonists, octreotide, clonidine and the selective M3 receptor antagonist, zamifenacin.

Irritable bowel syndrome: an update on therapeutic modalities

Irritable bowel syndrome (IBS) is the most common condition that a physician faces in the GI clinic. Of the general population, 10 - 25% suffer from symptoms judged to be IBS. The negative impact of this disease includes not only pain, suffering and direct medical expenses but also significant social and job-related consequences. IBS can be the result of dysfunction in any part of the brain-gut axis: alterations in the CNS caused by psychological or other factors, abnormal gastrointestinal motility, or heightened visceral sensations. Diagnosis is based on either the Manning or Rome-II criteria. Education, reassurance and emotional support are the cornerstones of successful treatment. The mainstays of the current therapeutic approach continue to be: stress management strategies, dietary modification entailing addition of dietary fibre and pharmacotherapy. Pharmacotherapy is still limited to treating symptoms. Newer drugs that modulate motility or drugs that modulate visceral sensation may be useful in selected cases. Psychopharmacological agents are useful in the treatment of IBS, especially in those with psychological co-morbidity. Alternative therapies such as homeopathy, acupuncture, special diets, herbal medication and several forms of psychological treatments and hypnotherapy are sought by many patients and are now being offered by physicians as treatment options, either alone or in conjunction with conventional forms of therapy in patients with refractory symptoms.

Review article: tegaserod

Tegaserod (Zelmac), an aminoguanidine indole derivative of serotonin, is a selective partial agonist highly selective for 5-HT(4) receptor with an affinity constant in the nanomolar range. Tegaserod does not cause adverse pharmacodynamic effects, is absorbed rapidly after oral administration and distributes widely into tissues. Pharmacokinetics of oral tegaserod are linear in the 2--12 mg dose range. After oral administration tegaserod is metabolized mainly pre-systemically; when absorbed, intact tegaserod is excreted as N-glucuronides mainly via the bile. No clinically relevant drug--drug interactions were identified. Tegaserod has proven safe in toxicity studies. In pharmacodynamic studies, tegaserod stimulated the peristaltic reflex in vitro, increased canine intestinal and colonic motility and transit, reduced visceral afferent firing or sensation in response to distension in animals, and accelerated gastric, small bowel and colonic transit in healthy patients, and small bowel transit in patients with constipation-predominant irritable bowel syndrome. Three large phase III randomized, double-blinded, and placebo-controlled trials were performed predominantly in females (approximately 85%) with constipation-predominant irritable bowel syndrome. Overall, phase III results support efficacy as assessed by the subject's global assessment of relief with significant improvement in secondary endpoints such as abdominal pain, bowel frequency and consistency. Tegaserod was well-tolerated; the most frequent adverse event was transient diarrhoea.

Symptom and health-related quality-of-life measures for use in selected gastrointestinal disease studies: a review and synthesis of the literature

Patient-rated symptom and health-related quality-of-life (HR-QOL) outcomes are important end-points for clinical trials of medical treatments for gastrointestinal (GI) disorders. Based on this review, patient outcomes research is focused on gastroesophageal reflux disease and dyspepsia, with a growing interest in irritable bowel syndrome but little research in gastroparesis. State-of-the-art for patient-rated symptom scales is rudimentary with an abundance of scales and little attention to systematic instrument development or comprehensive psychometric evaluation. Generally, disease-specific HR-QOL measures have been more systematically developed and evaluated psychometrically, but few have been incorporated into clinical trials. More comprehensive outcome assessments are needed to determine the effectiveness of new medical treatments for functional GI disorders. Future clinical trials of GI disorders should combine clinician assessments of outcomes and symptoms with patient-rated symptom and HR-QOL end-points.

Treatment of functional gastrointestinal disorders with antidepressant medications: a meta-analysis

BACKGROUND

Functional gastrointestinal disorders are common, accounting for up to 50% of gastroenterology referrals, and several randomized controlled trials have evaluated antidepressant therapy for their treatment.

METHODS

We performed a meta-analysis of published, English-language, randomized clinical trials on the use of antidepressants for the treatment of patients with functional gastrointestinal disorders.

RESULTS

Twelve randomized placebo-controlled trials of antidepressant treatment of functional gastrointestinal disorders were identified. One was excluded for using a combination of a tricyclic and neuroleptic agent. The medications included tricyclic antidepressants (amitriptyline [n = 3], clomipramine [n = 1], desipramine [n = 2], doxepin [n = 1], and trimipramine [n = 2]), and the antiserotonin agent, mianserin (n = 2). In addition, one trial compared two different antidepressants (mianserin and clomipramine) with placebo. Data were abstracted for the dichotomous outcome of symptom improvement in seven studies, and for the continuous variable of pain score in eight studies. The summary odds ratio for improvement with antidepressant therapy was 4.2 (95% confidence interval [CI]: 2.3 to 7.9), and the average standardized mean improvement in pain was equal to 0.9 SD units (95% CI: 0.6 to 1.2 SD units). On average 3.2 patients needed to be treated (95% CI: 2.1 to 6.5 patients) to improve 1 patient's symptom.

CONCLUSION

Treatment of functional gastrointestinal disorders with antidepressants appears to be effective. Whether this improvement is independent of an effect of treatment on depression needs further evaluation.

Effects of intravenous methylnaltrexone on opioid-induced gut motility and transit time changes in subjects receiving chronic methadone therapy: a pilot study

In this preliminary study, we evaluated the effects of methylnaltrexone, a peripheral opioid-receptor antagonist, on chronic opioid-induced gut motility and transit changes in four subjects with chronic methadone-induced constipation. Subjects participated in this single blind, placebo controlled study for up to 8 days. We gave placebo the first day; for the remainder of the study, we gave intravenous methylnaltrexone (0.05-0.45 mg/kg) twice daily. During the study period, we recorded oral-cecal transit time and opioid withdrawal symptoms, as well as laxation response based on the frequency and consistency of the stools. Subjects 1 and 2 who were administered methylnaltrexone 0.45 mg/kg, a dose previously administered in normal volunteers, showed immediate positive laxation. Subject 2, after positive laxation response, had severe abdominal cramping, but showed no opioid systemic signs of withdrawal. The subject was discontinued due to the cramping. In Subjects 3 and 4, we reduced the methylnaltrexone dose to 0.05-0.15 mg/kg. The latter two subjects also had an immediate laxation response during and after intravenous medication without significant side effects. The stool frequency of these four subjects increased from 1-2 times per week before the study to approximately 1.5 stool per day during the treatment period. Oral-cecal transit times of Subjects 1, 3, and 4 were reduced from 150, 150 and 150 min (after placebo) to 90, 60 and 60 min (with methylnaltrexone), respectively. Our preliminary results demonstrate that low dose intravenous methylnaltrexone effectively reversed chronic methadone-induced constipation and delay in gut transit time. Thus, we anticipate that cancer patients receiving chronic opioids may also have increased sensitivity to methylnaltrexone, and that low dose methylnaltrexone may have clinical utility in managing opioid-induced constipation in chronic-pain patients.

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.

Motility of the small intestine

Motility of the small intestine is controlled by myogenic, neural, and hormonal mechanisms and is modulated by external influences such as meals, central nervous system activation, and immune factors. Small-bowel dysmotility is recognized in a number of diseases, but its precise role in symptom generation remains unclear in many instances. We review publications that in the year under review added to the basic understanding of small-intestinal motility as well as its alteration in disease.

Evolving concepts in irritable bowel syndrome

Converging evidence from investigations of the peripheral and central aspects of bidirectional brain-gut interactions is beginning to shape a pathophysiological model of irritable bowel syndrome (IBS) and related functional gastrointestinal (GI) disorders. This neurobiological model includes alterations in autonomic, neuroendocrine, and pain modulatory mechanisms. The frequent association of IBS and other functional GI disorders with co-morbid affective disorders and temporal association of symptom exacerbation with psychosocial or physical stressors are consistent with alterations in the neurobiological mechanisms underlying the central stress response. Renewed interest in drug development for IBS has resulted in development of instruments for the better assessment of the impact of global symptoms on quality of life and in the development of candidate compounds undergoing clinical evaluation.