Tegaserod accelerates orocecal transit in patients with constipation-predominant irritable bowel syndrome

Does co-administration of a non-selective opiate antagonist enhance acceleration of transit by a 5-HT4 agonist in constipation-predominant irritable bowel syndrome? A randomized controlled trial

Opioid neurons exhibit tonic restraint on intestinal motility; opioid antagonists stimulate peristalsis and increase transit. In vitro, 5-hydroxytryptamine (5-HT4) agonists combined with selective opioid antagonists significantly increased colonic propulsion relative to a 5-HT4 agonist alone. We hypothesized that the combination of 5-HT4 agonist and non-selective opioid antagonist enhances intestinal transit more than either treatment alone in female constipation-predominant irritable bowel syndrome (C-IBS) patients. Our aim was to examine the effect of tegaserod 6 mg b.i.d. alone and combined with naltrexone 50 mg on intestinal transit and stool characteristics in females with C-IBS. Forty-eight patients were randomized to tegaserod alone, naltrexone alone or in combination with tegaserod or placebo for 6 days. Small bowel, ascending colon half-life (in pharmacokinetics) (t1/2), and colonic geometric centre (8, 24, 48 h) were assessed by scintigraphy. Tegaserod increased small bowel (P < 0.01) and colon transit (P < 0.01). Naltrexone did not accelerate colonic transit relative to placebo. Combination treatment did not significantly accelerate transit relative to tegaserod alone. Tegaserod and tegaserod with naltrexone resulted in looser stool form (P < 0.01). In female C-IBS patients, tegaserod accelerates small bowel and colon transit and contributed to looser stool consistency. Use of naltrexone, 50 mg, does not support the hypothesis that combination of 5-HT4 agonist and non-selective opioid antagonist enhances intestinal transit.

Effect of 5 days linaclotide on transit and bowel function in females with constipation-predominant irritable bowel syndrome

BACKGROUND & AIMS

Oral linaclotide, a novel agonist of guanylate cylase-C, stimulates intestinal fluid secretion and transit, and decreases visceral hypersensitivity in animal studies. In healthy volunteers, linaclotide was safe, well tolerated, increased stool frequency, and decreased stool consistency and time to first bowel movement. This randomized, double-blind, placebo-controlled study evaluated the effects of oral linaclotide, 100 and 1000 microg once daily, in 36 women with constipation-predominant irritable bowel syndrome; colonic transit was normal in >50% patients.

METHODS

Participants underwent 5-day baseline and 5-day treatment periods; gastrointestinal transit (by validated scintigraphy) and bowel function (by daily diaries) were assessed. Treatment effects were compared using analysis of covariance (baseline colonic transit as covariate) with pairwise comparisons of each dose vs placebo.

RESULTS

There was a significant overall treatment effect on ascending colon emptying half-time (P = .015) and overall colonic transit at 48 hours (P = .02) but not overall transit at 24 hours (P = ns), with a significant acceleration by linaclotide 1000 microg vs placebo (P = .004 and P = .01, respectively) but no significant effect of linaclotide 100-microg dose. There were significant overall treatment effects on stool frequency, stool consistency, ease of passage, and time to first bowel movement with a strong dose response for stool consistency (overall, P < .001). No safety issues were identified.

CONCLUSIONS

In women with constipation-predominant irritable bowel syndrome, linaclotide 1000 microg once daily significantly accelerated ascending colonic transit and altered bowel function. Further randomized controlled trials of clinical efficacy of linaclotide are warranted.

Irritable bowel syndrome: current approach to symptoms, evaluation, and treatment

There are frequent advances in knowledge about the clinical presentation, pathophysiology, and treatment of irritable bowel syndrome. It is important for clinicians to be aware of available therapies and the supporting evidence for those therapies to increase patient satisfaction. This is best achieved with a collaborative and long-term clinician-patient relationship and mutual commitment to modify therapy and try new modalities until the greatest relief of symptoms and improvement in health-related quality of life is achieved. This article reviews symptoms, comorbidities, gender differences, and measure of severity in irritable bowel syndrome and current and evidence-based approaches to evaluation and treatment, and the new symptom-based Rome III diagnostic criteria are reviewed and explained.

Constipation: evaluation and treatment of colonic and anorectal motility disorders

This article focuses on the colonic and anorectal motility disturbances that are associated with chronic constipation and their management. Functional chronic constipation consists of three overlapping subtypes: slow transit constipation, dyssynergic defecation, and irritable bowel syndrome with constipation. The Rome criteria may serve as a useful guide for making a clinical diagnosis of functional constipation. Today, an evidence-based approach can be used to treat patients with chronic constipation. The availability of specific drugs for the treatment of chronic constipation, such as tegaserod and lubiprostone, has enhanced the therapeutic armamentarium for managing these patients. Randomized controlled trials have also established the efficacy of biofeedback therapy in the treatment of dyssynergic defecation.

Sigmoid-colonic motility in health and irritable bowel syndrome: a role for 5-hydroxytryptamine

Abstract Evidence suggests that sigmoid-colonic motility is increased in patients with irritable bowel syndrome (IBS). 5-Hydroxytryptamine (5-HT) plays a role in the control of motility, but its involvement in the dysmotility seen in IBS remains unclear. To investigate the relationship between platelet depleted plasma 5-HT (PDP 5-HT) concentration and sigmoid-colonic motility in patients with IBS and healthy volunteers. Pre- and postprandial PDP 5-HT concentrations were assessed while recording sigmoid-colonic motility in 35 IBS patients (aged 19-53 years, eight male) and 16 healthy volunteers (aged 18-39 years, six male). Motility was recorded using a five-channel solid-state catheter introduced to a depth of 35 cm into an unprepared bowel. 5-Hydroxytryptamine concentration was measured by reverse-phase HPLC with fluorimetric detection. Irritable bowel syndrome patients had elevated concentrations of PDP 5-HT under fasting (P < 0.004) and fed (P = 0.079) conditions compared with controls. Likewise, they exhibited increased sigmoid-colonic motility under fasting (activity index: P < 0.02) and fed (P < 0.05) conditions compared with controls. Platelet depleted plasma 5-HT concentration positively correlated with colonic activity index under both fasting (r = 0.402; P = 0.003) and fed (r = 0.439; P = 0.001) conditions. These data show a possible relationship between endogenous concentrations of 5-HT and sigmoid-colonic motility recorded in both IBS and healthy subjects.

Mechanisms of serotonergic agents for treatment of gastrointestinal motility and functional bowel disorders

Most of the body's serotonin is released in the gut where it plays an important role in the control of gastrointestinal (GI) motility, sensitivity and muscle tone by activating different receptor subtypes. This review focuses on the known effects of selective serotonin reuptake inhibitor and serotonin receptor agonists and antagonists on the sensorimotor function of the GI tract and describes the therapeutic potential of these actions for GI motility and functional bowel disorders.

Effect of tegaserod on colonic transit time in male patients with constipation-predominant irritable bowel syndrome

BACKGROUND AND AIMS

Tegaserod is approved for the treatment of constipation-predominant irritable bowel syndrome (C-IBS) in females. The aim of this study was to evaluate the effect of tegaserod on colonic transit time (CTT) and symptoms in male patients with C-IBS.

METHODS

Forty-four males with C-IBS (Rome II) were enrolled. After a baseline washout period of 2 weeks, 40 patients were randomized to 6 mg twice daily of tegaserod or placebo for 12 weeks. Daily bowel habits and weekly satisfactory relief of symptoms were recorded. Total and segmental CTT were measured using radiopaque markers at baseline and after treatment.

RESULTS

The mean +/- SD for the total colonic, right colonic, left colonic and rectosigmoid transit time (in hours) were 18.96 +/- 3.92, 7.74 +/- 1.55, 5.64 +/- 1.51 and 5.58 +/- 2.2 in the tegaserod group compared to 22.47 +/- 3.73, 9.69 +/- 2.33, 6.6 +/- 1.32 and 6.18 +/- 2.22 in the placebo group at the end of 12 weeks. There was a statistically significant difference in the total, right and left CTT in the tegaserod group (P < 0.05) at the end of treatment. Global satisfactory relief at the end of 12 weeks was 75% in the tegaserod group and 50% in the placebo group (P > 0.05). Greater stool frequency occurred in the tegaserod group (P > 0.05). There was a significant decrease in the stool consistency at the end of 12 weeks in patients treated with tegaserod (P < 0.05).

CONCLUSIONS

Tegaserod causes significant acceleration of CTT in male patients with C-IBS. Although there was a trend towards improvement in bowel symptoms in the treated group, this effect was not statistically significant.

Pharmacogenomics and serotonergic agents: research observations and potential clinical practice implications

Pharmacogenomics of serotonin are potentially relevant in research and clinical practice. There are few proven examples of the importance of pharmacogenetics of serotonin-modifying agents used in functional gastrointestinal or motility disorders. Drug metabolism is dependent on function of the cytochrome P450 enzymes, such as 2D6 and 3A4. Genetic variations in transporters and translation mechanisms have been associated with responses to treatment in irritable bowel syndrome and in obesity. Research on the impact of polymorphisms of key proteins on the pharmacokinetics and pharmacodynamics of drugs that alter serotonin-mediated signalling will assist in explaining diverse responses to those drugs and ultimately improve clinical practice, individualizing medicine.

Effect of tegaserod on recto-sigmoid tonic and phasic activity in constipation-predominant irritable bowel syndrome

OBJECTIVES

In irritable bowel syndrome (IBS), the modulation of neural pathways may be altered and we have recently shown that postprandial recto-sigmoid tone modification is impaired. On pathophysiological grounds, we do not know whether this alteration may have a role in symptom onset and, in particular, whether an effective drug, such as tegaserod, can improve this response together with symptom severity.

METHODS

Twenty-two female patients with constipation-predominant IBS (IBS-C), diagnosed according to Rome II criteria, were studied. All subjects underwent an evaluation of the presence and severity of IBS symptoms and the recto-sigmoid barostat test to measure fasting and postprandial recto-sigmoid tone and phasic contractility. They were then randomly assigned to receive either tegaserod 6 mg b.i.d (12 patients) or placebo tablets (10 patients) for 4 wk, according to a double-blind protocol. Symptom assessment and recto-sigmoid tone and contractility were re-evaluated at the end of the treatment.

RESULTS

Both symptom severity and postprandial modification of recto-sigmoid tone improved only in the tegaserod group and a significant correlation was evident between the improvement of bloating and the improvement of postprandial recto-sigmoid tone modification. No effect of tegaserod on recto-sigmoid motility index or correlation between motility index and symptom improvement was evident.

CONCLUSIONS

In IBS-C female patients, the administration of tegaserod improves symptom severity and is accompanied by an improvement of recto-sigmoid tone response to a meal.

Recent advances in understanding the role of serotonin in gastrointestinal motility in functional bowel disorders: alterations in 5-HT signalling and metabolism in human disease

Serotonin (5-hydroxytryptamine, 5-HT) is present in abundance within the gut, most stored in enterochromaffin cell granules. It is released by a range of stimuli, most potently by mucosal stroking. Released 5-HT stimulates local enteric nervous reflexes to initiate secretion and propulsive motility. It also acts on vagal afferents altering motility and in large amounts induces nausea. Rapid reuptake by a specific transporter (serotonin transporter, SERT) limits its diffusion and actions. Abnormally increased 5-HT is found in a range of gastrointestinal disorders including chemotherapy-induced nausea and vomiting, carcinoid syndrome, coeliac disease, inflammatory bowel disease and irritable bowel syndrome (IBS) with diarrhoea (IBS-D), especially that developing following enteric infection. Impaired SERT has been described in IBS-D and might account for some of the increase in mucosal 5-HT availability. 5-HT(3) receptor antagonists inhibit chemotherapy-induced nausea and diarrhoea associated with both carcinoid syndrome and IBS. While IBS-D is associated with increased 5-HT postprandially, IBS with constipation (IBS-C) is associated with impaired 5-HT response and responds to 5-HT(4) agonists such as Prucalopride and 5-HT(4) partial agonists such as Tegaserod.

Economic evaluation of tegaserod vs. placebo in the treatment of patients with irritable bowel syndrome: an analysis of the TENOR study

OBJECTIVES

Tegaserod is effective, safe, and well-tolerated in the treatment of patients with irritable bowel syndrome (IBS) with constipation. The aim of this study was to assess, from a payer perspective, the cost-effectiveness of tegaserod in the treatment of IBS patients, based on the TEgaserod in NORdic region (TENOR) trial data.

METHODS

Female and male patients (Rome II criteria) were randomized to receive tegaserod 6 mg b.i.d. or placebo for 12 weeks. Patients (247 tegaserod; 238 placebo) completed the EuroQol EQ-5D questionnaire at baseline, Week 4, and Week 12. A 12-week economic study was undertaken to assess the incremental cost-effectiveness ratio (ICER) of tegaserod in terms of cost per quality-adjusted life-year (QALY) gained. Cost-effectiveness acceptability curves were calculated to estimate the probability of tegaserod being cost-effective at different benchmark values of cost per QALY gained.

RESULTS

By assuming a daily drug cost to payers of Euro 2, Euro 3, and Euro 4, the ICER of tegaserod ranges between Euro 19,000 and Euro 38,000 per QALY gained, with the percentage of the bootstrap estimates below the willingness to pay level of Euro 50,000 per QALY gained ranging between 90% and 69%.

CONCLUSIONS

This study established directly from a randomized controlled clinical trial that tegaserod is cost-effective in the treatment of non-D-IBS patients.

Novel and alternative therapies for childhood constipation

Constipation is a worldwide problem that affects many children. Treatment of constipation is largely based on clinical experience rather than on evidence-based controlled clinical trials. Stool softeners and cathartic agents in combination with behavioral interventions constitute the programs most commonly used to facilitate painless and frequent defecation. Long-term treatment is needed for most patients, and approximately 30% of children beyond puberty continue to struggle with symptoms of constipation, such as infrequent, painful evacuation of stools and fecal incontinence. Not surprisingly, chronicity of these bowel complaints may cause significant interference with the child's emotional growth and development. Development of new therapeutic strategies is necessary in order to treat these challenging patients more effectively. This review provides an overview of novel and alternative therapies, such as new drugs, surgery, and probiotics, that are being proposed for the treatment of childhood chronic constipation.

Irritable bowel syndrome and the Rome III criteria: for better or for worse?

The paper by Sperber et al. in this issue is an early evaluation of the Rome III criteria against the Rome II criteria for irritable bowel syndrome that throws up several important observations. A three to four-fold increase was observed in irritable bowel syndrome prevalence with the Rome III criteria. Individuals with the Rome II criteria had more doctor visits, perception of stress and a negative global feeling. There could be a shift of individuals between irritable bowel syndrome and other functional bowel disorder diagnostic groups such as functional constipation and functional bloating. In this review, it is suggested that rigid application of the symptom frequency and duration requirements of the older Rome criteria could have introduced a selection bias for patients with greater psychological disturbance, and that this could have impacted negatively on our perception and management of irritable bowel syndrome. The findings of Sperber et al. suggest that the new Rome III criteria may enable us to pay more attention to the average irritable bowel syndrome patient we see in our clinics as opposed to the chronically severe patient. It is proposed that improved management of our average patient may translate into better outcomes in terms of reduction in specialist referral, unnecessary surgery and potentially harmful alternative treatments.

Tegaserod for constipation-predominant irritable bowel syndrome

Tegaserod, a selective and partial agonist at the 5-hydroxytryptamine (5-HT [serotonin]) receptor subtype 4 (5-HT4), is the only United States Food and Drug Administration-approved drug for the treatment of constipation-predominant irritable bowel syndrome (IBS) in women. The drug's stimulation of 5-HT4 receptors on intestinal enterocytes increases peristaltic activity and fluid secretion into the gut lumen, facilitating stool passage. In addition, affinity of tegaserod for 5-HT4 receptors modulates visceral sensitivity, which helps alleviate abdominal pain associated with constipation-predominant IBS. The drug's pharmacokinetic and pharmacodynamic parameters do not differ significantly with age or sex. Tegaserod safely and effectively relieves overall gastrointestinal symptoms and abdominal discomfort and normalizes bowel habits in patients with constipation-predominant IBS. It is associated with few drug interactions. In clinical studies, tegaserod was well tolerated, and its adverse-effect profile was similar to that of placebo. Severe diarrhea, as well as abdominal pain, flatulence, headache, and nausea, were the most commonly reported events. Patients who experience severe diarrhea should discontinue the drug. With the data available, tegaserod remains an option for patients with constipation-predominant IBS.

Significant enhancement of esophageal pre-epithelial defense by tegaserod: implications for an esophagoprotective effect

BACKGROUND & AIMS

Tegaserod, a serotonin 5-hydroxytryptamine (5-HT)4 receptor agonist, is thought to stimulate intestinal secretions. The aim of the current study was to assess the effect of tegaserod vs placebo on salivary and esophageal protective factors in patients with gastroesophageal reflux disease (GERD).

METHODS

This study was a randomized, double-blind, placebo-controlled, cross-over trial in 38 GERD patients treated with tegaserod 6 mg twice a day vs placebo. Salivary samples were collected basally and during mastication. In addition, in 32 GERD patients, salivary and esophageal secretions also were collected during infusion of NaCl, HCl/pepsin, and NaCl in a consecutive fashion using a specially designed esophageal catheter. Saliva and esophageal perfusates were assessed for the pH, volume, content of buffers, protein, mucin, epidermal growth factor (EGF), transforming growth factor alpha (TGFalpha), and prostaglandin E (PGE)2 and analyzed statistically.

RESULTS

Salivary flow rates during administration of tegaserod increased over corresponding values during both basal conditions (P < .01) and mastication (P < .001). The rate of secretion of salivary bicarbonate and nonbicarbonate buffers also increased in basal conditions (P < .001 and P < .01, respectively) and during mastication (P < .05 and P = .05). Salivary EGF increased during mastication (P < .05), whereas PGE2 and TGF alpha increased in basal conditions (P < .05 and P < .01). Esophageal perfusate volumes increased during administration of tegaserod in basal conditions (P < .05), whereas esophageal EGF secretion increased after mucosal exposure to HCl/pepsin and subsequent final perfusion with NaCl (P < .05).

CONCLUSIONS

Significant stimulatory impact of 5-HT4 agonist on several salivary protective factors as well as esophageal EGF secretion may have esophagoprotective implications in patients with GERD and may help to address new therapies in the future.

A double-blind, randomized, placebo-controlled trial of itopride (100 and 200 mg three times daily) on gastric motor and sensory function in healthy volunteers

Itopride, a dopamine D2 antagonist and acetylcholinesterase inhibitor, significantly improved symptoms in patients with functional dyspepsia in one phase II randomized trial. However, the mechanisms by which itopride may improve symptoms are unknown. We aimed to compare the effects of two doses of itopride and placebo on gastric volumes, gastric emptying, small bowel transit and satiation in female and male healthy volunteers. Randomized, double-blind, placebo-controlled study evaluated gastric function before and after 7 days of itopride 100 mg (n = 16) or 200 mg (n = 15) or placebo (n = 15) t.i.d. Validated methods were used to study gastric accommodation (single photon emission computed tomography), gastric emptying and orocecal transit and satiation postnutrient challenge. The three arms were comparable with regard to age, gender and body mass index. There were no statistically significant effects of itopride on gastric emptying, orocecal transit, fasting gastric volume, maximum tolerated volume or aggregate symptom score with nutrient drink challenge. Postprandial (PP) change in gastric volume differed in the three groups (P = 0.019): 625[+/-28 (SEM)], 555(+/-26) and 512(+/-33) in placebo, itopride 100 and 200 mg groups, respectively. In healthy subjects, itopride reduced total PP gastric volume without accelerating gastric emptying or significantly altering gastric motor and sensory function in healthy individuals.

Tegaserod in the treatment of irritable bowel syndrome (IBS) with constipation as the prime symptom

Irritable bowel syndrome with constipation (IBS-C) as the predominant bowel symptom is a prevalent disorder, characterized by recurring abdominal pain/discomfort, bloating, and constipation, and imposes a significant socio-economic burden. Traditional treatments generally address just one of the multiple IBS symptoms. The efficacy and safety profile of tegaserod, a serotonin 5-HT(4) receptor agonist, has been demonstrated in several randomized, placebo-controlled, and open-label trials. This review discusses the major clinical trials of tegaserod, which have involved 8948 IBS patients. Overall, data reveal that tegaserod is an effective treatment for IBS-C, providing statistically significant relief of overall and multiple individual IBS-C symptoms (abdominal pain/discomfort, bloating, and constipation) in both placebo-controlled and "real-life" open-label settings. Repeat treatments with tegaserod were also shown to be effective, which is noteworthy given the chronic and episodic nature of IBS. Moreover, tegaserod was associated with improvements in patients' quality of life and work productivity. Data also indicate that tegaserod is well tolerated over the short-term (4 weeks), long-term (12 months), and repeated treatments. Diarrhea is the only adverse event consistently associated with tegaserod and was generally mild and transient. Overall, tegaserod has been demonstrated to offer effective and well-tolerated treatment of IBS-C, providing patients with meaningful symptom relief.

Efficacy of tegaserod for functional constipation in Chinese subjects: a randomized double-blind controlled trial in a single centre

BACKGROUND

Tegaserod has been shown to be effective in chronic constipation in Western population. Aim We investigated if tegaserod is equally effective in Chinese population.

MATERIALS AND METHODS

Two hundred and fifty patients were randomized to a double-blinded 8-week treatment of tegaserod 6 mg b.d. or placebo. Response during weeks 1-4 was defined as an increase in complete spontaneous bowel motion >/=1/week. Secondary efficacy included response during weeks 1-8, individual symptoms and scores, quality of life and global assessment of bowel habits and constipation.

RESULTS

One hundred and nine patients from the treatment group and 107 from the placebo group completed the 8-week treatment. Responder rates was 47.7% vs. 29% for the treatment and placebo groups (P = 0.005). The sustained complete spontaneous bowel motion rate was 29.4% vs. 15.7% in the two groups (P = 0.016). The response rates were higher than that reported previously in the Caucasian studies. There was improvement in the scores for stool form scale, bothersomeness of constipation, abdominal distension/bloating and satisfaction of bowel habit (P < 0.05). The mental score was higher in the treatment group (46.8 +/- 9 vs. 43.6 +/- 10, P = 0.01).

CONCLUSIONS

Tegaserod is effective in relieving chronic constipation in Chinese population. The efficacy observed may be higher than that in Western population.

A randomized, double-blind, placebo-controlled trial assessing the efficacy and safety of tegaserod in patients from China with chronic constipation

AIM

To evaluate the efficacy and safety of tegaserod, 6 mg twice daily (b.i.d.), in men and women with chronic constipation (CC) from China.

METHODS

This was a multicenter, double-blind, placebo-controlled study. Following a 2-wk treatment-free baseline period, patients were randomized to receive either tegaserod (6 mg b.i.d.) or placebo (b.i.d.) for 4 wk. An analysis of covariance with repeated measures was used to determine the overall effect of treatment for the primary efficacy variable; the change from baseline in the number of complete spontaneous bowel movements (CSBMs) during the 4-wk treatment period. Secondary efficacy endpoints included other measures of response in terms of CSBMs, and patients' daily and weekly assessment of bowel habits. Safety was also assessed, based on the incidence and severity of adverse events (AEs).

RESULTS

A total of 607 patients were randomized to receive either tegaserod (n = 304) or placebo (n = 303). Tegaserod treatment resulted in a rapid and significant increase from baseline in the adjusted mean number of CSBMs per week over wk 1-4 compared with placebo (1.39 vs 0.91, P = 0.0002). A statistically significant difference in favor of tegaserod was also observed for a mean increase > or = 1 CSBM/wk over wk 1-4 (47.7% vs 35.0%, tegaserod vs placebo, respectively, P = 0.0018) and for the absolute number of > or = 3 CSBMs/wk over wk 1-4 (25.0% vs 14.5%, tegaserod vs placebo, respectively, P = 0.0021). Improvements in other symptoms of CC were also seen in the tegaserod group, including improved stool form and reduced straining. In addition, more patients in the tegaserod group reported satisfactory relief from their constipation symptoms. The frequency and severity of AEs was comparable between tegaserod and placebo groups, with the exception of a greater incidence of diarrhea in patients receiving tegaserod (3.6%) compared with placebo (1.7%).

CONCLUSION

Tegaserod treatment improved multiple symptoms of CC and was associated with a favorable safety profile.

Efficacy of tegaserod in chronic constipation in men

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Pharmacodynamic effects of a novel prokinetic 5-HT receptor agonist, ATI-7505, in humans

ATI-7505, an investigational 5-HT(4) receptor agonist, was designed to have similar activity as cisapride without the cardiac adverse effects, i.e. without QT prolongation. In addition, ATI-7505 is not metabolized by CYP450. The aim of the study was to assess the effect of ATI-7505 on gastrointestinal (GI) and colonic transit in healthy humans. A randomized, parallel-group, double-blind, placebo-controlled study evaluated effects of 9-day treatment with ATI-7505 (3, 10 or 20 mg t.i.d.) on scintigraphic GI and colonic transit in healthy volunteers (12 per group). Primary endpoints were gastric-emptying (GE) T(1/2), colonic geometric centre (GC) at 24 h and ascending colon (AC) emptying T(1/2). Daily stool diaries were kept. Analysis of covariance assessed overall treatment group differences, followed by post hoc unadjusted pairwise comparisons. There were borderline overall treatment effects (decrease) on GE T(1/2) (P = 0.154); the 20 mg t.i.d. of ATI-7505-accelerated GE vs placebo (P = 0.038). ATI-7505 increased colonic transit (GC24, P = 0.031) with fastest transit at 10 mg t.i.d. vs placebo (P = 0.065). ATI-7505 accelerated AC emptying T(1/2) (overall P = 0.075) with 10 mg dose vs placebo (P = 0.042). There was looser stool (Bristol stool form scale, overall P = 0.056) with the 10 and 20 mg t.i.d. doses. No safety issues were identified. ATI-7505 accelerates overall colonic transit and tends to accelerate GE and AC emptying and loosen stool consistency.

The serotonin signaling system: from basic understanding to drug development for functional GI disorders

Serotonin is an important gastrointestinal signaling molecule. It is a paracrine messenger utilized by enterochromaffin (EC) cells, which function as sensory transducers. Serotonin activates intrinsic and extrinsic primary afferent neurons to, respectively, initiate peristaltic and secretory reflexes and to transmit information to the central nervous system. Serotonin is also a neurotransmitter utilized by a system of long descending myenteric interneurons. Serotonin is synthesized through the actions of 2 different tryptophan hydroxylases, TpH1 and TpH2, which are found, respectively, in EC cells and neurons. Serotonin is inactivated by the serotonin reuptake transporter (SERT)-mediated uptake into enterocytes or neurons. The presence of many serotonin receptor subtypes enables selective drugs to be designed to therapeutically modulate gastrointestinal motility, secretion, and sensation. Current examples include tegaserod, a 5-HT(4) partial agonist, which has been approved for treatment of irritable bowel syndrome (IBS) with constipation in women and for chronic constipation in men and women. The 5-HT(3) antagonists, granisetron and ondansetron, are useful in combating the nausea associated with cancer chemotherapy, and alosetron is employed in the treatment of IBS with diarrhea. Serotonergic signaling abnormalities have also been putatively implicated in the pathogenesis of functional bowel diseases. Other compounds, for which efficacy has not been rigorously established, but which may have value, include tricyclic antidepressants and serotonin selective reuptake inhibitors to combat IBS, and 5-HT(1) agonists, which enhance gastric accommodation, to treat functional dyspepsia. The initial success encountered with serotonergic agents holds promise for newer and more potent insights and therapies of brain-gut disorders.

Irritable bowel syndrome in the 21st century: perspectives from Asia or South-east Asia

Asian irritable bowel syndrome (IBS) studies not only confirm the truth of this functional disorder but also describe the current disease situation of this continent, with its variable socioeconomic backgrounds. Most Asian community IBS prevalence is within 5-10%, regardless of gender or ethnic character. As well as meeting the main Rome II criteria, Asian IBS subjects also have many minor symptoms. Thus this recommendation remains useful to diagnose Asian IBS. Also, female patients commonly express constipation-predominant (C-) symptoms. Extra-colonic symptoms are common in Asia, for example dyspepsia, insomnia and irritable urinary bladder. Asian IBS subjects do experience psychological disturbances including anxiety, depression, agoraphobia and neuroticism. Accordingly, their quality of life is poor and there is absenteeism leading to excessive physician visits. Abnormal gut motor and sensory functions have been indicated among the Asian IBS subjects. Now, there is evidence of altered colonic neuroimmune function leading to gut hypersensitivity and dysmotility. An Asia-Pacific trial also confirmed tegaserod efficacy on female C-IBS subjects. More than 90% of nurses have very limited IBS knowledge, and are unable even to explain it clearly. In conclusion, Western recommended criteria clearly diagnose Asian IBS and many factors are mutual leading to IBS. Current IBS treatments remain useful but additional reeducation for medical professionals appears to be needed.

Role of motility in chronic diarrhoea

Patients complaining of 'chronic diarrhoea' usually mean the passage of loose, urgent stools. Chronic diarrhoea is a feature of malabsorption; it may also be seen in the 'dumping syndrome' which follows gastric surgery, small intestinal bacterial overgrowth, bile salt malabsorption and in malabsorption of simple sugars including most commonly lactose, fructose and sorbitol. Excessively rapid entry of chyme into the small or large intestine generates propulsive motor patterns leading to accelerated transit. Inflammation is associated with decreased normal mixing motor patterns but increased propulsive motility including high amplitude propagated contractions (HAPCs). Evidence for abnormal small intestinal motility in the diarrhoea associated with irritable bowel syndrome (IBS) is conflicting and any difference appears small. Increased colonic HAPCs with increased propulsion is seen in IBS with diarrhoea (IBS-D). Stress-induced colonic motility is increased in IBS-D with hyper-responsiveness to corticotrophin releasing factor (CRF). Long-lasting increases in mucosal serotonin availability may contribute to the chronic diarrhoea seen in IBS-D and coeliac disease. Treatments for abnormal motility in chronic diarrhoea include those designed to correct specific underlying abnormalities including octreotide, antibiotics, colestyramine, specific food avoidance and anti-inflammatory agents. There are also treatments aimed primarily at altering motility directly including opiates, 5HT3 receptor antagonists and amitriptyline.

Fecal Incontinence: a woman's view

Fecal incontinence (FI) has a prevalence of 2-7% in the general community and increases substantially in hospitalized patients and nursing home residents. Incontinent patients often isolate themselves from society for fear of having an incontinent episode in public. Few of these patients ever discuss this ailment with their doctor, despite a significant increase in depression and anxiety. Women have gender-specific medical and surgical conditions that predispose them to FI such as pregnancy, scleroderma, MS, IBS, childbirth, and pelvic surgeries. This article will address multiple facets of FI, but will focus specifically on issues related to women.

Intestinal motility disturbances in intensive care patients pathogenesis and clinical impact

BACKGROUND

Gastrointestinal motility disturbances in critically ill patients are frequent in the ICU setting, causing considerable discomfort and are associated with increased rates of morbidity and mortality. This review focuses on the pathophysiological basis of intestinal motility, the major patterns of pathological motility alterations, the impact on patient outcome, and current therapeutic options.

DISCUSSION

Intestinal motility is controlled by the enteric nervous system, modulated by hormones and extrinsic afferent and efferent neurons. Pathological motility disturbances can affect the stomach, small bowel, and colon separately or in combination. Changes in esophageal motor activity contribute to the aspiration of gastric juice, whereas early enteral feeding most frequently fails due to gastric intolerance. Disturbances in digestive and interdigestive motility patterns and the inability to switch motor activity from the interdigestive to the digestive pattern also contribute to feeding disability and thus to increased morbidity and mortality as well.

CONCLUSIONS

The therapeutic options for motility disturbances in critically ill patients include the adjustment of electrolyte imbalances, tailored fluid management, early enteral feeding, appropriate management of catecholamines and drugs used for analgosedation, and prokinetic drugs. Unfortunately, the therapeutic options for treating motility disturbances in ICU patients are still limited. This situation requires careful assessment of ICU patients with respect to gut motility disturbances and their pathophysiological mechanisms and an individually tailored treatment to prevent further aggravation of existing motility disturbances.

Irritable bowel syndrome: recent and novel therapeutic approaches

Irritable bowel syndrome (IBS) is a highly prevalent functional gastrointestinal disorder affecting up to 3-15% of the general population in Western countries. It is characterised by unexplained abdominal pain, discomfort and bloating in association with altered bowel habits. The pathophysiology of IBS is considered to be multifactorial, involving disturbances of the brain-gut-axis: IBS has been associated with abnormal gastrointestinal motor functions, visceral hypersensitivity, psychosocial factors, autonomic dysfunction and mucosal inflammation. Traditional IBS therapy is mainly symptom oriented and often unsatisfactory. Hence, there is a need for new treatment strategies. Increasing knowledge of brain-gut physiology, mechanisms, and neurotransmitters and receptors involved in gastrointestinal motor and sensory function have led to the development of several new therapeutic approaches. This article provides a systematic overview of recently approved or novel medications that show promise for the treatment of IBS; classification is based on the physiological systems targeted by the medication. The article includes agents acting on the serotonin receptor or serotonin transporter system, novel selective anticholinergics, alpha-adrenergic agonists, opioid agents, cholecystokinin antagonists, neurokinin antagonists, somatostatin receptor agonists, neurotrophin-3, corticotropin releasing factor antagonists, chloride channel activators, guanylate cyclase-c agonists, melatonin and atypical benzodiazepines. Finally, the role of probiotics and antibacterials in the treatment of IBS is summarised.

Arzneimitteltherapie des Reizdarmsyndroms

The therapy of patients with irritable bowel syndrome (IBS) is often challenging, especially if a broad spectrum of symptoms is present and trigger factors, such as the influence of diet or stress, are lacking. Current pathogenetic concepts propose central or peripheral alterations that cause disturbed gastrointestinal function (motility, visceral sensitivity) and subsequent symptoms. These alterations are possibly related to psychological (stress, depression, anxiety) and biological (post-infectious residuals, micro-inflammation) influences. Since no universally effective medical treatment is available to treat the causes of the disease, standard medical therapy is symptom directed (especially for pain, constipation and diarrhoea). In addition to well established drugs (like spasmolytics, opioids and laxatives), newly developed compounds including those with other primarily indications (e.g. antidepressants) are available for highly differentiated individualized therapies. New medical approaches which are currently undergoing evaluation, promise further progress in the treatment of IBS.

The effects of tegaserod on oesophageal function and bolus transport in healthy volunteers: studies using concurrent high-resolution manometry and videofluoroscopy

BACKGROUND

Tegaserod is a partial 5-hydroxytryptamine 4 receptor agonist with prokinetic effects on the gastrointestinal tract, its effects on oesophageal function are unknown.

AIM

A randomized, placebo controlled, double-blind trial assessed the effect of tegaserod on the oesophagus in healthy, asymptomatic subjects.

METHOD

A 7-day course of tegaserod 6 mg b.d. vs. placebo was prescribed (n = 17/21 completed both phases of study). High-resolution manometry and pH measurements were performed before and after a test meal. Bolus transport of liquids and solids was studied by high-resolution manometry and videofluoroscopy.

RESULTS

Tegaserod had no effect on lower oesophageal sphincter pressure compared with placebo, peristaltic velocity increased (P < 0.001) and distal contractile pressure decreased slightly (P < 0.05). Transient lower oesophageal sphincter relaxations and reflux were infrequent regardless of treatment. During the studies of bolus transport, high-resolution manometry revealed that tegaserod promoted mid-oesophageal contractility (P < 0.02) and shortened the 'proximal transition zone' (P < 0.05), the level where bolus escape occurred most frequently. These effects had no effect on liquid bolus transport; however a non-significant trend to improved solid bolus transport was observed (66% vs. 31%;P = 0.07).

CONCLUSION

Tegaserod did not alter lower oesophageal sphincter pressure, but had significant effects on peristaltic function. High-resolution manometry promoted mid-oesophageal contractility during bolus transport. This effect was associated with a non-significant trend to improved solid bolus transit.

Update on gastrointestinal scintigraphy

Nuclear medicine offers a variety of studies for evaluating motility throughout the gastrointestinal tract. Gastric emptying remains the "gold standard" for studying gastric motor function, but its application in most centers remains limited to measuring only total gastric emptying in spite of data that show assessment of both fundal and antal function is of clinical value for evaluating patients with dyspepsia. Similarly, newer methods to study small bowel and colon transit have not gained widespread use. This review summarizes the state-of-the-art of prior established and newer scintigraphic studies with an emphasis on their clinical applications.

Double-blind, randomized, placebo-controlled study to evaluate the effects of tegaserod on gastric motor, sensory and myoelectric function in healthy volunteers

BACKGROUND

The effects of tegaserod on gastric accommodation and postprandial satiety remain unclear.

AIM

To compare the effects of tegaserod 6 mg twice daily vs. placebo on gastric volumes, postprandial symptoms, gastric emptying, small bowel transit and the surface electrogastrogram in female and male healthy volunteers.

METHODS

Randomized, double-blind, placebo-controlled study evaluated gastric function before and after 7 days of tegaserod 6 mg twice daily (n = 21) vs. placebo (n = 20) in healthy volunteers. Validated methods were used to study gastric emptying, myoelectrical activity, volumes and satiation postnutrient challenge.

RESULTS

There were no significant effects of tegaserod on the primary endpoints assessing gastric function: emptying of solids or liquids, total gastric volumes or myoelectrical activity. Maximum tolerated volume and aggregate symptom score with nutrient challenge on placebo were 1,035 mL (+/-44) and 130 (+/-15) vs. 989 mL (+/-43) and 117 (+/-15) during tegaserod, respectively (all P = N.S.). Postprandial change in proximal gastric volume by single photon emission-computed tomography was decreased in females on tegaserod (246 +/- 30) vs. placebo (358 +/- 32) (P = 0.015). Proximal fasting volumes in females were increased on tegaserod (126 +/- 12) vs. placebo (92 +/- 13) (P = 0.066).

CONCLUSIONS

While tegaserod decreased proximal gastric volume change after a meal, it does not appear to have significant effects on gastric motor and sensory function in healthy individuals. Further studies are required in patients with disturbances of gastric motor and sensory function.

Emerging drugs for irritable bowel syndrome

Irritable bowel syndrome (IBS) is one of the most common chronic gastrointestinal disorders, yet its pathophysiology is incompletely understood and pharmacological treatments remain unsatisfactory. Current therapeutic choices include a range of drugs aimed at normalising bowel habits, reducing pain or treating comorbid psychological symptoms. However, this individual symptom-targeted approach remains unsatisfactory in terms of global symptom relief and patient satisfaction. In the last decade, further characterisation of IBS pathophysiology has provided new and exciting targets at different levels of the brain-gut axis for the development of several candidate drugs. Advances in clinical trial design will help to evaluate these compounds in different IBS patient populations.

Use of novel prokinetic agents to facilitate return of gastrointestinal motility in adult critically ill patients

PURPOSE OF REVIEW

Intolerance of enteral feeding due to impaired gastrointestinal motility is common in critically ill patients. Strategies to prevent or treat gastrointestinal hypomotility include the use of prokinetic agents. Many currently employed prokinetic agents are associated with serious adverse drug reactions. The novel prokinetic agents - alvimopan, tegaserod, and dexloxiglumide - are reviewed.

RECENT FINDINGS

Alvimopan exerts mixed, but generally favorable, effects on restoration of gastrointestinal motility in patients with postoperative ileus. The observation of increased opioid requirements (without increased pain scores) and associated clinical ramifications requires further study. Tegaserod stimulates the peristaltic reflex and improves motility in multiple sites along the gastrointestinal tract. Its efficacy in improving gastrointestinal hypomotility in the critically ill population has not yet been determined. Furthermore, its use has been associated with the development of ischemic colitis and increased requirement for abdominal/pelvic surgery. Dexloxiglumide may be beneficial for improving gastric emptying in critically ill patients, especially those receiving lipid-enriched enteral feeds.

SUMMARY

Novel prokinetic agents show promise for management of gastrointestinal hypomotility in the critically ill population. However, further study is required before these agents can be recommended for use.

Pseudo-obstruction intestinale chronique

Chronic intestinal pseudo-obstruction (CIPO) is a disease characterized by episodes resembling mechanical obstruction in the absence of organic, systemic, or metabolic disorders. Pseudo-obstruction is an uncommon condition and can result from primary (40%) or secondary (60%) causes. The most common symptoms are nausea, vomiting, abdominal distension, abdominal pain and constipation or diarrhea. These symptoms are usually present many years before CIPO diagnosis. They can lead to severe electrolyte disorders and malnutrition. Principles for management of patients with CIPO are: to establish a correct clinical diagnosis in excluding mechanical obstruction; to perform a symptomatic and physiologic assessment of the gastrointestinal tract involved; to look for extra-intestinal manifestations, especially for myopathy and neuropathy; to discuss in some cases a surgery for full-thickness intestinal biopsies, and/or a neuromuscular biopsy in case of mitochondrial cytopathy suspicion. The management is primarily focused on symptom control and nutritional support to prevent weight loss and malnutrition. Treatment of CIPO includes prokinetic agents which may help to reduce gastrointestinal symptoms Courses of antibiotics may be needed in patients with symptoms suggestive of bacterial overgrowth. When necessary, enteral nutrition is preferred. In carefully selected patients, feeding jejunostomy with or without decompression gastrostomy may be tried. Long term parenteral nutrition should be reserved for patients who can not tolerate enteral nutrition. Intestinal transplantation can be discussed in selected patients.

Modulation of intestinal gas dynamics in healthy human volunteers by the 5-HT receptor agonist tegaserod

OBJECTIVES

Bloating in irritable bowel syndrome (IBS) may result from impaired intestinal gas transit and is reduced by the 5-HT4 agonist tegaserod. Abnormal serotonergic function underlies many IBS symptoms, but the role of 5-HT4 pathways in regulating gas dynamics under healthy conditions is unexplored. We hypothesized that 5-HT4 activation by tegaserod stimulates gas transit in healthy individuals.

METHODS

Sixteen normal volunteers underwent jejunal perfusion of gas mixtures (88% N2, 5.5% O2, 6.5% CO2) at 11.2 mL/min x 3 h under control conditions and 3 h after oral tegaserod 6 mg on separate days. Gas collected from an intrarectal catheter was quantified using a barostat.

RESULTS

Under control conditions, gas evacuation after a lag period (1,959 +/- 428 s) was predominantly pulsatile with expulsion of 1,984 +/- 90 mL. A mean of 29 +/- 2 boluses with volumes of 72 +/- 5 mL were expelled. In 10 subjects with physiologic degrees of gas retention in control studies (248 +/- 73 mL), tegaserod increased expulsion from 1,768 +/- 73 to 1,973 +/- 37 mL and decreased retention to 43 +/- 37 mL (p < 0.05). Total volumes expelled as boluses were greater after tegaserod (1,708 +/- 73 vs 1,846 +/- 59 mL, p < 0.05) from increased bolus numbers in four subjects and increased bolus volumes in seven. Nonpulsatile continuous flow tended to increase with tegaserod (43 +/- 7 vs 126 +/- 43 mL, p= 0.10). Tegaserod did not increase evacuation in individuals without physiologic gas retention.

CONCLUSIONS

The 5-HT4 agonist tegaserod promotes evacuation of jejunally perfused gas mixtures in healthy humans. These findings provide the foundation for future investigations into use of 5-HT4 agonists in conditions of pathologic gas retention.

Irritable bowel syndrome and chronic constipation: emerging drugs, devices, and surgical treatments

Irritable bowel syndrome (IBS) and chronic constipation (CC) are two of the most common functional disorders of the gut. CC and IBS are estimated to affect up to 20% and 27% of the North American population respectively. Although not life-threatening, CC and IBS can profoundly and negatively affect quality of life and are associated with a significant economic burden related to direct and indirect annual health-care costs. Possible etiologies for IBS and CC include alterations in visceral sensation and gastrointestinal motility. IBS may be caused by disturbances in brain-gut interactions affecting gastrointestinal motility and visceral sensitivity. Research efforts in CC have begun to identify abnormalities in myenteric neurons, alterations in neurotransmitters and their receptors, and incoordination of the muscles of the pelvic floor or anorectum. Both disorders may be influenced by genetic predisposition, environmental factors, and stress. In this article, the safety and efficacy of traditional and emerging therapies for CC and IBS are examined. In addition, their pathophysiology and symptoms are briefly reviewed.

Disturbed bowel habits in patients with non-ulcer dyspepsia

BACKGROUND; Emerging medications for non-ulcer-dyspepsia, such as the serotonin-receptor modulators, also affect bowel habits by altering colonic transit. If drugs that alter colonic function were to prove useful in non-ulcer dyspepsia, knowledge of baseline bowel habit disturbances would be potentially critical.

AIM

To estimate the rate of non-ulcer dyspepsia patients with clinically relevant constipation or diarrhoea potentially precluding use of motility agents.

METHODS

Consecutive patients with non-ulcer dyspepsia (n = 79), gastro-oesophageal reflux disease (n = 135) and organic upper gastrointestinal disease (upper gastrointestinal disease; n = 36) completed a validated symptom questionnaire evaluating predominant bowel habits in the last year.

RESULTS

Prevalence of constipation was higher in non-ulcer dyspepsia (34%) than in gastro-oesophageal reflux disease (P = 0.01) and organic upper gastrointestinal disease (P = 0.01), prevalence of alternating diarrhoea/constipation (24%) and diarrhoea (22%) was similar, while prevalence of normal bowel habits was significantly less in non-ulcer dyspepsia (20%; P = 0.01 vs. gastro-oesophageal reflux disease and P < 0.01 vs. organic upper gastrointestinal disease). Constipation was particularly frequent in ulcer-like and dysmotility-like non-ulcer dyspepsia, while prevalence of diarrhoea was lowest in dysmotility-like non-ulcer dyspepsia. A normal bowel habit was equally uncommon in male (21%) and female non-ulcer dyspepsia patients (20%).

CONCLUSIONS

Only one of five non-ulcer dyspepsia patients had normal bowel habits based on clinical symptoms; constipation is particularly prevalent. Patients with functional dyspepsia who are prescribed motility altering drugs should be evaluated by taking a thorough bowel habit history.

Current gut-directed therapies for irritable bowel syndrome

Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder that can present with a wide array of symptoms that make treatment difficult. Current therapies are directed at relieving symptoms of abdominal pain or discomfort, bloating, constipation, and diarrhea. Pharmacologic agents used to treat IBS-associated pain include myorelaxants, peppermint oil, and peripherally acting opiates. Dicyclomine and hyoscyamine, the two myorelaxants available in the United States, have not been proven effective in reducing abdominal pain in patients with IBS. The efficacy of peppermint oil is debated, but methodological problems with existing studies preclude definitive judgment. Loperamide is ineffective for relief of abdominal pain. For IBS patients with excessive abdominal bloating, a small number of studies suggest that bacterial eradication with gut-directed antibiotics and bacterial reconstitution with nonpathogenic probiotics may reduce flatulence. For constipation-predominant (C-IBS) symptoms, current treatment options include fiber supplementation, polyethylene glycol, and tegaserod. Soluble fibers (ispaghula, calcium polycarbophil, psyllium) are more effective than insoluble fibers (wheat bran, corn fiber) in alleviating global symptoms and relieving constipation, although fiber in general has marginal benefit in treatment of overall IBS symptoms. Polyethylene glycol increases bowel frequency in chronic constipation, but its overall efficacy against IBS is unclear. Tegaserod, a 5-HT(4) agonist, demonstrates superiority over placebo in improving bowel frequency and stool consistency and alleviating abdominal pain and bloating in women with C-IBS. Overall global symptoms are modestly improved with tegaserod when compared with placebo. Additional agents under investigation for C-IBS include the ClC(2) chloride channel opener lubiprostone, mu-opioid receptor antagonist alvimopan, and 5-HT(4) agonist renzapride. For diarrhea-predominant (D-IBS) symptoms, available therapies include loperamide, alosetron, and clonidine. Alosetron, a 5-HT(3) antagonist, is superior to placebo for reducing bowel frequency, improving stool consistency, and relieving abdominal pain in women with D-IBS. However, alosetron is available under a restricted license because of concerns for ischemic colitis and severe constipation necessitating colectomy. Clonidine may be helpful in alleviating global symptoms for D-IBS patients.

Effects of a 5-HT(4) receptor agonist on oesophageal function and gastro-oesophageal reflux: studies using combined impedance-manometry and combined impedance-pH

BACKGROUND

5-HT(4) receptor agonists are used as promotility agents of the stomach, small and large intestine. There is limited information on the influence of 5-HT(4) receptor agonists on oesophageal function and gastro-oesophageal reflux.

AIM

To evaluate the effects of tegaserod, a 5-HT(4) agonist on oesophageal function using impedance-manometry and postprandial reflux using impedance-pH monitoring.

METHODS

Twenty healthy volunteers were enrolled in a double-blind randomized three-period crossover placebo-controlled study. Impedance-manometry and impedance-pH monitoring after a refluxogenic meal were performed at baseline and after 2 days of dosing with tegaserod 6 mg b.d. or placebo. Multichannel intraluminal impedance-EM recorded pressure and bolus transit data during standardized swallows. Multichannel intraluminal impedance-pH monitoring recorded the number of 2-h postprandial acid and non-acid reflux episodes.

RESULTS

We found no significant difference in distal oesophageal amplitude when subjects received placebo (median 94.5; range: 53-243 mmHg) or tegaserod (93.6; 43-216 mmHg). Bolus transit time was similar during dosing with placebo (7.1; 5.3-9.4 s) and tegaserod (7.2; 5.9-11.1 s). We observed similar numbers of acid and non-acid reflux episodes during dosing with placebo (5; 0-15 and 3; 0-18, respectively) and tegaserod (2; 0-11 and 4; 0-19, respectively).

CONCLUSION

Tegaserod, a 5-HT(4) receptor agonist does not change oesophageal motility and gastro-oesophageal reflux parameters in healthy volunteers.

Safety and tolerability of tegaserod in patients with chronic constipation: pooled data from two phase III studies

BACKGROUND & AIMS

Studies show that tegaserod effectively relieves the symptoms of chronic constipation/idiopathic constipation (CC). This pooled analysis assessed the safety and tolerability of tegaserod in a large dataset of CC patients.

METHODS

Adverse event (AE) data were pooled from 2 double-blind, placebo-controlled phase III trials of 12 weeks' duration. Post hoc analysis was conducted for the most frequent AEs (incidence, >or=3%).

RESULTS

Eight hundred eighty-one, 861, and 861 patients received tegaserod 6 mg twice a day, 2 mg twice a day, or placebo, respectively. Most AEs were mild/moderately severe. AE incidence was similar for the tegaserod 6 mg and 2 mg twice a day (57.1% and 56.3%, respectively) and placebo groups (59.6%) and most frequent in the gastrointestinal system (tegaserod 6 mg twice a day, 25.8%; 2 mg twice a day, 22.5%; placebo, 24.6%). Headache, the most common AE, was slightly more frequent in the placebo group (tegaserod 6 mg twice a day, 11.0%; 2 mg twice a day, 10.1%; placebo, 13.2%). Diarrhea (generally transient and resolved with continued treatment) was the only AE with a statistically significant difference between groups (tegaserod 6 mg twice a day 6.6% vs placebo 3.0%, P=.0005). Serious AE incidence (1.4% overall) was comparable across treatment groups, although abdominal surgery was less common in the combined tegaserod (0.5%) than the placebo group (1.0%). Discontinuation as a result of AEs was slightly higher in tegaserod 6 mg twice a day patients (5.7%; 2 mg twice a day, 3.3%; placebo, 3.7%), mainly because of diarrhea. Laboratory and electrocardiogram parameters were comparable across groups.

CONCLUSIONS

Tegaserod is well tolerated by patients with CC during 12 weeks of treatment.

Effect of a selective chloride channel activator, lubiprostone, on gastrointestinal transit, gastric sensory, and motor functions in healthy volunteers

Chloride channels modulate gastrointestinal neuromuscular functions in vitro. Lubiprostone, a selective type 2 chloride channel (ClC-2) activator, induces intestinal secretion and has been shown to relieve constipation in clinical trials; however, the effects of lubiprostone on gastric function and whole gut transit in humans are unclear. Our aim was to compare the effects of the selective ClC-2 activator lubiprostone on maximum tolerated volume (MTV) of a meal, postprandial symptoms, gastric volumes, and gastrointestinal and colonic transit in humans. We performed a randomized, parallel-group, double-blind, placebo-controlled study evaluating the effects of lubiprostone (24 microg bid) in 30 healthy volunteers. Validated methods were used: scintigraphic gastrointestinal and colonic transit, SPECT to measure gastric volumes, and the nutrient drink ("satiation") test to measure MTV and postprandial symptoms. Lubiprostone accelerated small bowel and colonic transit, increased fasting gastric volume, and retarded gastric emptying. MTV values were reduced compared with placebo; however, the MTV was within the normal range for healthy adults in 13 of 14 participants, and there was no significant change compared with baseline measurements. Lubiprostone had no significant effect on postprandial gastric volume or aggregate symptoms but did decrease fullness 30 min after the fully satiating meal. Thus the ClC-2 activator lubiprostone accelerates small intestinal and colonic transit, which confers potential in the treatment of constipation.

Identification of neurons that express 5-hydroxytryptamine4 receptors in intestine

5-Hydroxytryptamine (5-HT) is an endogenous stimulant of intestinal propulsive reflexes. It exerts its effects partly through 5-HT4 receptors; 5-HT4 receptor agonists that are stimulants of intestinal transit are in clinical use. Both pharmacological and recent immunohistochemical studies indicate that 5-HT4 receptors are present on enteric neurons but the specific neurons that express the receptors have not been determined. In the present work, we describe the characterization of an anti-5-HT4 receptor antiserum that reveals immunoreactivity for enteric neurons and other cell types in the gastrointestinal tract. With this antiserum, 5-HT4 receptor immunoreactivity has been found in the muscularis mucosae of the rat oesophagus, a standard assay tissue for 5-HT4 receptors. It is also present in the muscularis mucosae of the guinea-pig and mouse oesophagus. In guinea-pig small intestine and rat and mouse colon, 5-HT4 receptor immunoreactivity occurs in subpopulations of enteric neurons, including prominent large neurons. Double-staining has shown that these large neurons in the guinea-pig small intestine are also immunoreactive for two markers of intrinsic primary afferent neurons, cytoplasmic NeuN and calbindin. Some muscle motor neurons in the myenteric ganglia are immunoreactive for this receptor, whereas it is rarely expressed by secretomotor neurons. Immunoreactivity also occurs in the interstitial cells of Cajal but is faint in the external muscle. Expression of the protein and mRNA has been confirmed in extracts containing enteric neurons. The observations suggest that one site of action of 5-HT4 receptor agonists is the intrinsic primary afferent neurons.

Physiological modulation of intestinal motility by enteric dopaminergic neurons and the D2 receptor: analysis of dopamine receptor expression, location, development, and function in wild-type and knock-out mice

Dopaminergic neurons are present in both plexuses of the murine bowel and are upregulated after extrinsic denervation but play unknown roles in enteric nervous system (ENS) physiology. Transcripts encoding dopamine (DA) receptors D1-D5 were analyzed by reverse transcription-PCR in stomach approximately duodenum approximately ileum approximately proximal > > distal colon. Dissected muscle and myenteric plexus contained transcripts encoding D1-D3 and D5, whereas mucosa contained D1 and D3-D5. D1-D5 expression began in fetal gut [embryonic day 10 (E10)], before the appearance of neurons (E12), and was sustained without developmental regulation through postnatal day 1. In situ hybridization revealed that subsets of submucosal and myenteric neurons contained mRNA encoding D2 or D3. Immunoblots confirmed that D1, D2, and D5 receptor proteins were present from stomach through distal colon. Subsets of submucosal and myenteric neurons were also D1, D2, or D3 immunoreactive. When double labeled by in situ hybridization, these neurons contained mRNA encoding the respective receptors. Total gastrointestinal transit time (TGTT) and colonic transit time (CTT) were measured in mice lacking D2, D3, or D2 plus D3. Both TGTT and CTT were decreased significantly (motility increased) in D2 and D2 plus D3, but not D3, knock-out animals. Mice lacking D2 and D2 plus D3 but not D3 were smaller than wild-type littermates, yet ate significantly more and had greater stool frequency, water content, and mass. Because motility is abnormal when D2 is absent, the net inhibitory DA effect on motility is physiologically significant. The early expression of DA receptors is also consistent with the possibility that DA affects ENS development.

Treatment of gastroparesis: a multidisciplinary clinical review

This clinical review on the treatment of patients with gastroparesis is a consensus document developed by the American Motility Society Task Force on Gastroparesis. It is a multidisciplinary effort with input from gastroenterologists and other specialists who are involved in the care of patients with gastroparesis. To provide practical guidelines for treatment, this document covers results of published research studies in the literature and areas developed by consensus agreement where clinical research trials remain lacking in the field of gastroparesis.

Systematic review: pathophysiology and management of gastrointestinal dysmotility in systemic sclerosis (scleroderma)

Gastrointestinal dysmotility in systemic sclerosis (scleroderma) is prevalent in 90% of patients, increasing morbidity and in some cases mortality. The resultant gastrointestinal complications are usually extensive, involving many regions of the gut from the oesophagus to the anus. Collagen replacement of vascular and enteric smooth muscle results in hypomotility, lumen dilatation, tensile rigidity and eventual loss of organ functions. The aim of this paper is to provide an overview of systemic sclerosis-related gastrointestinal dysmotility and available/potential therapeutic options. We evaluated published data on the pathophysiology and management of gastrointestinal dysmotility in systemic sclerosis patients using the MEDLINE database for English and non-English articles from 1966 to July 2005. Based on this systematic review, lifestyle and medical therapy approaches are preferred as they often improve and/or ameliorate symptoms. Surgery is only recommended with serious, rare complications such as bowel perforation or ischaemia. Alternative therapies such as acupuncture-based therapies are well tolerated, with clinical improvement and may be of potential therapeutic benefit for systemic sclerosis gastrointestinal dysmotility. Further elucidation of initiating and persistent mechanisms of systemic sclerosis-related gastrointestinal dysmotility will optimize the development of a multidisciplinary and more directed treatment regimen.

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.