Effects of alosetron on gastrointestinal transit time and rectal sensation in patients with irritable bowel syndrome

BACKGROUND: Alosetron, a 5-HT3-receptor antagonist, relieves abdominal pain and improves bowel function in non-constipated, female patients with irritable bowel syndrome. 5-HT3 antagonists delay colonic transit, increase colonic compliance, and increase small intestinal water absorption. AIM: To evaluate the effects of alosetron on gastrointestinal and colonic transit, rectal compliance and rectal sensation in irritable bowel syndrome. METHODS: A double-blind, placebo-controlled, two-dose study of alosetron was performed in 25 non-constipated irritable bowel syndrome patients, with paired studies before and after 4 weeks of treatment with placebo (n=5), 1 mg alosetron (n=10) or 4 mg (n=10) alosetron b.d. Gastrointestinal and colonic transit were measured by scintigraphy. Rectal compliance and sensation were assessed by rectal balloon distention with a barostat. RESULTS: There was a trend (P=0.06) for 1 mg alosetron to increase rectal compliance (median pressure at half maximum volume 11 mmHg after alosetron vs. 15.6 mmHg before alosetron). The 1 mg b.d. alosetron dose non-significantly retarded proximal colonic transit. Alosetron and placebo reduced sensory scores relative to baseline values; none of the changes induced by alosetron was significant relative to placebo. CONCLUSIONS: Alosetron had no significant effect on gastrointestinal transit or rectal sensory and motor mechanisms in non-constipated irritable bowel syndrome patients in this study. Alosetron's effects on colonic sensorimotor function and central sensory mechanisms deserve further evaluation.     

Effect of alosetron on left colonic motility in non-constipated patients with irritable bowel syndrome and healthy volunteers

BACKGROUND: Alosetron is a 5-hydroxytryptamine-3 receptor antagonist reducing symptoms in female patients with diarrhoea-predominant irritable bowel syndrome, and is known to increase the colonic transit time. AIM: To study the effect of alosetron on left colonic phasic motility in ambulant non-constipated patients with irritable bowel syndrome and healthy volunteers. METHODS: In a double-blind, randomized, crossover design, 10 patients with irritable bowel syndrome and 12 sex- and age-matched volunteers were treated for two 7-day periods with alosetron, 4 mg b.d., or placebo b.d. On day 6 of each treatment period, a six-channel solid-state manometric catheter was positioned in the left colon and 24 h motility was studied on day 7. The periprandial phasic motility around dinnertime was evaluated in the descending and sigmoid colon. The high-amplitude propagated contraction frequency and characteristics were calculated. RESULTS: Alosetron appeared to increase the overall periprandial frequency in the sigmoid colon (P=0.043) and the mean amplitude of colonic contractions in the descending colon (P=0.007). The high-amplitude propagated contraction frequency was higher on alosetron during the second half of the day for patients with irritable bowel syndrome (P=0.002), with increased mean propagation length of high-amplitude propagated contractions (P=0.001). The stool frequency (P=0.024) and stool consistency score (P=0.002) were decreased by alosetron. CONCLUSIONS: The 5-hydroxytryptamine-3 receptor antagonist alosetron marginally increased left colonic periprandial phasic motility. Alosetron increased the number and propagation length of high-amplitude propagated contractions, which were paradoxically accompanied by a decrease in stool frequency and a firming of stool consistency.     

Alosetron, a 5-HT3 receptor antagonist, delays colonic transit in patients with irritable bowel syndrome and healthy volunteers

BACKGROUND: Alosetron is a potent and selective 5-HT3 receptor antagonist, which has been shown to be beneficial in the treatment of female patients with non-constipated irritable bowel syndrome. AIMS: To investigate the effect of alosetron on whole gut, small bowel and colonic transit in patients with irritable bowel syndrome (Study 1) and healthy volunteers (Study 2). SUBJECTS: Thirteen patients with irritable bowel syndrome and 12 healthy volunteers. METHODS: Both studies were randomized, double-blind, placebo-controlled with a two-way crossover design, in which each subject received alosetron (2 mg b.d. administered orally) or placebo for 8 days. Mean whole gut transit was determined from the excretion of radio-opaque markers; small bowel transit was determined from rise in breath hydrogen after a meal; and colonic transit and segmental transit were evaluated from abdominal X-ray. In addition, colonic transit was calculated by subtracting small bowel transit time from whole gut transit time. RESULTS: Alosetron increased colonic transit time by prolonging left colonic transit in both patients with irritable bowel syndrome and controls. This resulted in a tendency for the whole gut transit to be delayed in irritable bowel syndrome patients (P=0.128), which was confirmed in controls (P=0.047). CONCLUSION: Alosetron delays colonic transit by prolonging left colonic transit. These results add to the body of evidence suggesting that alosetron should have a therapeutic role in patients with non-constipated irritable bowel syndrome.     

Lipid-induced colonic hypersensitivity in irritable bowel syndrome: the role of 5-HT3 receptors

BACKGROUND: Irritable bowel syndrome patients demonstrate colonic hypersensitivity after duodenal lipid infusion. AIM: To investigate the role of 5-hydroxytryptamine-3 (5-HT3) receptors in this sensory component of the gastrocolonic response in irritable bowel syndrome. METHODS: Fifteen female patients with diarrhoea-predominant irritable bowel syndrome completed a trial with the 5-HT3 receptor antagonist alosetron (1 mg b.d.) or placebo (b.d.) over 15 days, followed by the alternative treatment. Each treatment period was followed by a colonic distension trial before and after duodenal lipids. Changes in colonic thresholds, tone and compliance and viscerosomatic referral pattern after lipids were compared between treatments. RESULTS: With placebo, the colonic thresholds after lipids were significantly reduced for all studied sensations, whereas, with alosetron, the thresholds were significantly reduced only for first sensation and discomfort, but not for gas and pain. The reductions in thresholds did not differ significantly between treatments, but the pain threshold after alosetron tended to be less reduced compared with placebo (P = 0.10). The effects of lipids on tone, compliance and viscerosomatic referral pattern were unaffected by alosetron relative to placebo. CONCLUSIONS: 5-HT3 receptor antagonism reduces the lipid-induced colonic hypersensitivity in irritable bowel syndrome. However, 5-HT3 receptors do not seem to be the principal mediator, but may be a cofactor for the exaggerated sensory component of the gastrocolonic response in irritable bowel syndrome.     

Improvement in pain and bowel function in female irritable bowel patients with alosetron, a 5-HT3 receptor antagonist

BACKGROUND: No currently available treatment provides consistent relief of irritable bowel syndrome. Colonic sensory and motor function are modulated partly through 5HT3-receptors. AIM: To evaluate effects of the 5HT3-receptor antagonist, alosetron, in irritable bowel syndrome. METHODS: Randomized, double-blind, placebo-controlled, dose-ranging (1, 2, 4, 8 mg b.d. alosetron), 12-week trial in 370 patients with diarrhoea-predominant or alternating constipation and diarrhoea irritable bowel syndrome. Weekly measurement of adequate relief was the key end-point; other irritable bowel syndrome symptoms were collected daily using an electronic phone system. RESULTS: Alosetron (1 mg or 2 mg b.d.) significantly (P < 0.05 vs. placebo) increased the proportion of females, but not males, reporting adequate relief. Stool consistency, frequency and percentage days with urgency improved over placebo (P < 0.05) within the first month with all doses of alosetron, and persisted throughout the trial with all doses in female patients. With 1 mg b.d. alosetron, females had improved stool consistency and urgency within the first week, and adequate relief and improved stool frequency within the first 2 weeks. There was no consistent improvement in bowel function among male patients. CONCLUSION: In female irritable bowel syndrome patients with predominant diarrhoea or alternating constipation and diarrhoea, alosetron is effective in treatment of abdominal pain and discomfort and bowel-related symptoms.     

A double-blind, randomized, placebo-controlled dose-ranging study to evaluate the efficacy of alosetron in the treatment of irritable bowel syndrome

BACKGROUND: Irritable bowel syndrome is a common gastrointestinal disorder characterized by abdominal pain and discomfort and altered bowel habit. Antagonism at the 5-HT3 receptor may be of benefit in the treatment of irritable bowel syndrome. AIMS: To evaluate the effect of 12 weeks of treatment with alosetron, a 5-HT3 receptor antagonist at doses of 0.1 mg b.d., 0.5 mg b.d. and 2 mg b.d. in irritable bowel syndrome patients. METHODS: A double-blind, placebo-controlled, parallel-group study with a 2-week screening and a 12-week treatment period was conducted. A total of 462 patients (335 female) recorded details of the severity of their abdominal pain, and bowel function daily on a diary card throughout the study. At monthly clinic visits patients recorded the severity of their abdominal pain/discomfort and diarrhoea on a visual analogue scale. RESULTS: In the total population and in the female subpopulation (but not in males) alosetron 2 mg b.d. significantly increased the proportion of pain-free days and decreased the visual analogue scale score for diarrhoea compared with placebo. Alosetron at doses of 0.5 mg b.d. and 2 mg b.d. led to a significant hardening of stool, and a reduction in stool frequency in the total population. CONCLUSION: Alosetron at a dose of 2 mg b.d. is an effective treatment for female patients with irritable bowel syndrome.     

Effect of long-term treatment with octreotide on rectal sensitivity in patients with non-constipated irritable bowel syndrome

BACKGROUND: Acute administration of octreotide reduces visceral perception and therefore has been suggested as potential treatment for irritable bowel syndrome. Whether prolonged treatment with octreotide also reduces visceral sensitivity and improves gastrointestinal symptoms remains, however, unknown. AIM: To investigate the effect of a slow release preparation of octreotide on rectal sensitivity and symptoms in irritable bowel syndrome patients. METHODS: Forty-six non-constipated irritable bowel syndrome patients (52% female, 19-63 years) participated. Before and after 8 weeks of treatment with octreotide (Sandostatin LAR 20 mg i.m.) or placebo, patients underwent a barostat study to assess the rectal sensitivity. During a 2-week run-in period and treatment, abdominal pain, defecation frequency, consistency and symptom relief were scored weekly. RESULTS: Octreotide, but not placebo, significantly increased the threshold for first sensation. Thresholds for urge to defecate and discomfort/pain and rectal compliance were not altered by either treatment. Octreotide improved stool consistency compared with placebo (loose stools after eight weeks: octreotide: 52%, placebo: 81%, P < 0.05). In contrast, abdominal pain and defecation frequency were not affected. CONCLUSIONS: Although the threshold of first rectal sensation increased and stool consistency improved, long-term treatment with octreotide, at least at the current dose used, has no visceral analgesic effect and fails to improve irritable bowel syndrome symptoms.     

Pharmacology and clinical experience with alosetron

Alosetron (Lotronex) is a potent, highly selective 5-HT₃ antagonist. Animal models have shown it to be active in anxiety, psychosis, cognitive impairment, emesis and drug withdrawal, though its application in humans has been almost entirely restricted to irritable bowel syndrome (IBS). Alosetron does not cause adverse pharmacodynamic effects, is absorbed rapidly after oral administration and is widely distributed throughout tissues after oral or iv. dosing in animals. Its metabolism is rapid and extensive with N-demethylation, hydroxylation and oxidation. The drug, or its two principal metabolites, is equally excreted through the biliary tract and kidneys. Alosetron has proved safe in a range of toxicity studies; at high repeated dosing, clinical signs were transient and repeated administration produced no significant adverse effects on fertility, reproductive performance or fetal development. In pharmacokinetic studies, bioavailability of alosetron in healthy volunteers is approximately 60% and the plasma half-life is about 1.5 h. There are some gender differences in the pharmacokinetic profile, with 30 - 50% higher alosetron concentrations in females. No consistent differences in alosetron serum concentrations between the young and elderly were observed. The pharmacokinetics of single, oral doses of alosetron are linear up to 8 mg. In human pharmacodynamic studies, alosetron increased basal jejunal water and electrolyte absorption, increased colonic transit time and, consequently, whole gut transit time. Alosetron has been evaluated in two large Phase II trials (randomised, double-blinded, placebo-controlled) and in Phase III trials which included a four-week observation period after cessation. Dose response studies suggested that the effective dosages could be between 1 and 2 mg, twice-daily. In Phase II trials, alosetron, 1 mg b.i.d., resulted in a greater proportion of non-constipated IBS patients reporting adequate relief of pain and discomfort, as well as improvement of bowel symptoms, frequency, urgency and stool consistency when compared with placebo. However, this beneficial effect was seen exclusively among females. Phase III studies evaluated exclusively females with non-constipated IBS and confirmed the results of the Phase II studies. Alosetron was well-tolerated in all studies, with the most frequently recorded adverse event being constipation. Thus, alosetron appears promising in the treatment of abdominal pain and discomfort and normalising of bowel function in patients with non-constipated IBS. It also improves quality of life, has a high degree of tolerability and has an excellent safety profile to date.     

Alosetron relieves pain and improves bowel function compared with mebeverine in female nonconstipated irritable bowel syndrome patients

BACKGROUND: Irritable bowel syndrome is one of the most common gastrointestinal disorders, yet no therapy convincingly controls the multiple symptoms of this syndrome. AIM: To compare the efficacy and tolerability of the new 5-HT3-receptor antagonist alosetron and the smooth muscle relaxant mebeverine in a double-blind, multicentre, randomized trial. METHODS: Six hundred and twenty-three nonconstipated females with irritable bowel syndrome were randomized to receive alosetron 1 mg twice daily (n=319) or mebeverine 135 mg three times daily (n=304) for 12 weeks, followed by a 4-week post-treatment period. The primary efficacy end-point was monthly responders for adequate relief of irritable bowel syndrome related abdominal pain and discomfort (defined as patients reporting adequate relief on at least 2 out of 4 weeks). Secondary end-points included assessments of bowel function, including urgency, stool frequency and stool consistency. RESULTS: There were significantly more responders in the alosetron group compared with mebeverine at months 2 and 3 (P < 0.01). Compared with mebeverine, the alosetron group experienced significant decreases in proportion of days with urgency and mean stool frequency, and had firmer stools within 1 week of starting treatment. A similar proportion of patients reported adverse events in the two treatment groups. CONCLUSIONS: In nonconstipated female irritable bowel syndrome patients, alosetron is significantly more effective than mebeverine in improving symptoms.     

Pharmacology and clinical experience with alosetron

Alosetron (Lotronex) is a potent, highly selective 5-HT(3) antagonist. Animal models have shown it to be active in anxiety, psychosis, cognitive impairment, emesis and drug withdrawal, though its application in humans has been almost entirely restricted to irritable bowel syndrome (IBS). Alosetron does not cause adverse pharmacodynamic effects, is absorbed rapidly after oral administration and is widely distributed throughout tissues after oral or iv. dosing in animals. Its metabolism is rapid and extensive with N-demethylation, hydroxylation and oxidation. The drug, or its two principal metabolites, is equally excreted through the biliary tract and kidneys. Alosetron has proved safe in a range of toxicity studies; at high repeated dosing, clinical signs were transient and repeated administration produced no significant adverse effects on fertility, reproductive performance or fetal development. In pharmacokinetic studies, bioavailability of alosetron in healthy volunteers is approximately 60% and the plasma half-life is about 1.5 h. There are some gender differences in the pharmacokinetic profile, with 30 - 50% higher alosetron concentrations in females. No consistent differences in alosetron serum concentrations between the young and elderly were observed. The pharmacokinetics of single, oral doses of alosetron are linear up to 8 mg. In human pharmacodynamic studies, alosetron increased basal jejunal water and electrolyte absorption, increased colonic transit time and, consequently, whole gut transit time. Alosetron has been evaluated in two large Phase II trials (randomised, double-blinded, placebo-controlled) and in Phase III trials which included a four-week observation period after cessation. Dose response studies suggested that the effective dosages could be between 1 and 2 mg, twice-daily. In Phase II trials, alosetron, 1 mg b.i.d., resulted in a greater proportion of non-constipated IBS patients reporting adequate relief of pain and discomfort, as well as improvement of bowel symptoms, frequency, urgency and stool consistency when compared with placebo. However, this beneficial effect was seen exclusively among females. Phase III studies evaluated exclusively females with non-constipated IBS and confirmed the results of the Phase II studies. Alosetron was well-tolerated in all studies, with the most frequently recorded adverse event being constipation. Thus, alosetron appears promising in the treatment of abdominal pain and discomfort and normalising of bowel function in patients with non-constipated IBS. It also improves quality of life, has a high degree of tolerability and has an excellent safety profile to date.     

Review article: clinical pharmacology of alosetron

Alosetron, a new 5-HT₃ antagonist is in development for the treatment of the irritable bowel syndrome. A series of randomized placebo-controlled double-blind clinical pharmacology studies have been performed in healthy volunteers and irritable bowel syndrome patients to evaluate the pharmacokinetics and some of the pharmacodynamic properties of this drug. Alosetron was shown to dose-dependently inhibit the 5-HT-induced skin flare response, increase colonic transit time and increase basal jejunal water and electrolyte absorption, in healthy volunteers. In irritable bowel syndrome patients, alosetron increased colonic compliance. Alosetron had no effect on the perception of gastric distension or on meal-stimulated gastric acid secretion. Orally alosetron has ≈ 60% bioavailability and a half-life of 1.5 h. At doses of 1 mg or more, it has a pharmacodynamic duration of action which justifies twice a day dosing. These data support the potential use of alosetron in the treatment of irritable bowel syndrome.     

Selective 5-hydroxytryptamine antagonism: a role in irritable bowel syndrome and functional dyspepsia?

Background: Abnormalities of gut motility and visceral pain perception are both thought to be involved in the pathogenesis of irritable bowel syndrome and may be susceptible to modulation by drugs affecting the various 5-HT receptor subtypes. The aim of this study was to investigate the therapeutic potential of a 5-HT₃ antagonist in irritable bowel syndrome.
Methods: Fifty patients with irritable bowel syndrome were treated with ondansetron, a highly selective 5-HT₃ antagonist, in a double-blind, placebo-controlled cross-over study. In addition to assessing its effect on the classical symptoms of irritable bowel syndrome (abdominal pain, distension and disordered bowel habit) its effect on symptoms often seen in irritable bowel syndrome, but more commonly associated with functional dyspepsia, was also examined.
Results: Ondansetron reduced bowel frequency ( P =0.035) and improved stool consistency ( P =0.002) in diarrhoea predominant irritable bowel syndrome and did not cause a deterioration of bowel habit in constipation predominant subjects. No statistically significant improvement was seen for abdominal pain or distension, although those patients who did respond were approximately twice as likely to be taking ondansetron than placebo. It was also found that ondansetron significantly improved the upper gastrointestinal symptoms of post-prandial epigastric discomfort ( P =0.008), flatulence ( P =0.022) and heartburn ( P =0.003).
Conclusion: The results of this study justify evaluation of the therapeutic potential of selective 5-HT antagonists in both functional dyspepsia and irritable bowel syndrome.     

Alosetron and irritable bowel syndrome

Alosetron (Lotronex^®, GlaxoSmithKline) is a potent and selective 5-HT₃-receptor antagonist approved by the FDA for the treatment of women with diarrhoea-predominant irritable bowel syndrome (IBS) in whom conventional therapy has failed. Studies involving healthy volunteers and IBS patients have demonstrated a beneficial effect of treatment with alosetron on global IBS symptoms, abdominal pain and discomfort, altered bowel function as well as improvement of quality of life (QOL). Data from animals studies suggest the involvement of 5-HT₃ receptors on intrinsic primary afferent neurons in the mediation of the effect of alosetron on gastrointestinal motility and secretion. While definitive proof of a visceroanalgesic action is not available, an additional central mechanism of action is suggested by findings obtained in animal models, as well as from human brain imaging studies. Alosetron shows a greater effectiveness in women, and the role of genetic factors underlying inter-individual differences in the response to alosetron is currently under investigation. The most frequent adverse event associated with the use of alosetron is constipation and in some rare cases, the development of colonic mucosal ischaemia. In the following review, the most recent reported effects of alosetron on gastrointestinal motility, visceral sensitivity and anxiety, both in terms of preclinical and clinical data will be discussed. The impact of alosetron on QOL in IBS patients and the safety of treatment with alosetron, will also be covered.     

Alosetron and irritable bowel syndrome

Alosetron (Lotronex, GlaxoSmithKline) is a potent and selective 5-HT(3)-receptor antagonist approved by the FDA for the treatment of women with diarrhoea-predominant irritable bowel syndrome (IBS) in whom conventional therapy has failed. Studies involving healthy volunteers and IBS patients have demonstrated a beneficial effect of treatment with alosetron on global IBS symptoms, abdominal pain and discomfort, altered bowel function as well as improvement of quality of life (QOL). Data from animals studies suggest the involvement of 5-HT(3) receptors on intrinsic primary afferent neurons in the mediation of the effect of alosetron on gastrointestinal motility and secretion. While definitive proof of a visceroanalgesic action is not available, an additional central mechanism of action is suggested by findings obtained in animal models, as well as from human brain imaging studies. Alosetron shows a greater effectiveness in women, and the role of genetic factors underlying inter-individual differences in the response to alosetron is currently under investigation. The most frequent adverse event associated with the use of alosetron is constipation and in some rare cases, the development of colonic mucosal ischaemia. In the following review, the most recent reported effects of alosetron on gastrointestinal motility, visceral sensitivity and anxiety, both in terms of preclinical and clinical data will be discussed. The impact of alosetron on QOL in IBS patients and the safety of treatment with alosetron, will also be covered.     

Alosetron

Alosetron, a 5-HT(3)-receptor antagonist that is very closely related to ondansetron in terms of both chemistry and pharmacology, is the first compound of this type to be developed for irritable bowel syndrome. Clinical data for up to 3 months of treatment indicate that alosetron is orally bioavailable in tablet form, is well tolerated and is significantly superior to both placebo and the smooth muscle relaxant, mebeverine, in improving perception of visceral pain, spasms and diarrhea in female diarrhea-predominant irritable bowel syndrome. In males, symptoms were not alleviated to a statistically significant extent.     

Pilot study of the efficacy of renzapride on gastrointestinal motility and symptoms in patients with constipation-predominant irritable bowel syndrome

AIM: To investigate the efficacy and safety of renzapride, a potent 5-hydroxytryptamine type-4 receptor full agonist and 5-hydroxytryptamine type-3 receptor antagonist in patients with constipation-predominant irritable bowel syndrome. METHODS: In this dose-escalating pilot study, 17 patients with constipation-predominant irritable bowel syndrome received placebo, renzapride 2 mg o.d. and renzapride 2 mg b.d. sequentially for 28 days. Response was determined by radio-opaque marker measurement of overall gastrointestinal and segmental colonic transit and patients' assessment of their irritable bowel syndrome symptoms. RESULTS: Renzapride reduced mean overall gastrointestinal transit time (placebo, 2.9 +/- 1.6 days; renzapride 2 mg o.d., 2.6 +/- 1.4 days; renzapride 2 mg b.d., 1.9 +/- 1.6 days) (P = 0.024) and accelerated segmental colonic transit, with statistically significant differences for renzapride 2 mg b.d. over placebo in caecum/ascending colon (P = 0.019) and descending colon (P = 0.022). Renzapride also reduced abdominal pain, increased the number of pain-free days and improved stool consistency. The frequency of reported adverse events was similar on renzapride and placebo. CONCLUSIONS: Renzapride is well-tolerated, stimulates gastrointestinal transit and improves symptoms in patients with constipation-predominant irritable bowel syndrome, particularly at the 2 mg b.d. dose, where improvements in gastrointestinal symptoms were evident over placebo. This study has established proof of concept and supports further investigation of renzapride in patients with constipation-predominant irritable bowel syndrome.     

Randomized,double-blind,placebo-controlled trial of prednisolone in post-infectious irritable bowel syndrome

BACKGROUND: Post-infectious irritable bowel syndrome is associated with increased serotonin-containing enterochromaffin cells and lymphocytes in rectal biopsies. Animal studies have suggested that steroids reduce the lymphocyte response and suppress some of the post-infectious changes in neuromuscular function. AIM: To evaluate whether steroids reduce the number of enterochromaffin cells and improve the symptoms of post-infectious irritable bowel syndrome. METHODS: Twenty-nine patients with post-infectious irritable bowel syndrome underwent a randomized, double-blind, placebo-controlled trial of 3 weeks of oral prednisolone, 30 mg/day. Mucosal enterochromaffin cells, T lymphocytes and mast cells were assessed in rectal biopsies before and after treatment, and bowel symptoms were recorded in a daily diary. RESULTS: Initial enterochromaffin cell counts were increased and correlated with initial lamina propria T-lymphocyte counts (r = 0.460, P = 0.014). Enterochromaffin cell counts did not change significantly after either prednisolone (- 0.8% +/- 9.2%) or placebo (7.9% +/- 7.9%) (P = 0.5). Although lamina propria T-lymphocyte counts decreased significantly after prednisolone (22.0% +/- 5.6%, P = 0.003), but not after placebo (11.5% +/- 8.6%, P = 0.1), this was not associated with any significant treatment-related improvement in abdominal pain, diarrhoea, frequency or urgency. CONCLUSIONS: Prednisolone does not appear to reduce the number of enterochromaffin cells or cause an improvement in symptoms in post-infectious irritable bowel syndrome. Other approaches to this persistent condition are indicated.     

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

AIM: To investigate the efficacy and safety of tegaserod, a novel 5-HT(4) receptor partial agonist, in a randomized, double-blind, placebo-controlled, 12-week treatment, multicentre study. METHODS: Eight hundred and eighty-one patients with irritable bowel syndrome, characterized by abdominal pain, bloating and constipation, received tegaserod, 2 mg b.d. or 6 mg b.d., or placebo for 12 weeks. RESULTS: Tegaserod, 2 mg b.d. and 6 mg b.d., showed a statistically significant relief of overall irritable bowel syndrome symptoms, measured by a weekly, self-administered questionnaire. At end-point, treatment differences from placebo were 12.7% and 11.8% for 2 mg b.d. and 6 mg b.d., respectively. The effect of tegaserod was noted as early as week 1, and was sustained over the 12-week treatment period. Individual irritable bowel syndrome symptoms assessed daily also showed a statistically significant improvement of abdominal discomfort/pain, number of bowel movements and stool consistency, and a favourable trend for reducing days with significant bloating. Adverse events were similar in all groups, with transient diarrhoea being the only adverse event seen more frequently with tegaserod than placebo. CONCLUSIONS: Based upon the results of this study, tegaserod offers rapid and sustained relief of the abdominal pain and constipation associated with irritable bowel syndrome. Tegaserod is also well tolerated.     

Neurokinin-1-receptor antagonism decreases anxiety and emotional arousal circuit response to noxious visceral distension in women with irritable bowel syndrome: a pilot study

Background Irritable bowel syndrome is characterised by chronic abdominal pain and frequent comorbid anxiety. The substance P/neurokinin‐1 receptor system is implicated in the regulation of both pain and anxiety, suggesting a potential therapeutic target in IBS. Aim To determine whether inhibition of the neurokinin‐1 receptor (NK1R) will change pain ratings and brain responses to experimental visceral pain and anxiety symptoms in women with IBS or not. Methods Rome II positive IBS women were recruited for a double‐blind, placebo‐controlled, cross‐over study of NK1R antagonist AV608. Treatment periods were 3 weeks with a 2‐week washout period. Functional MRI during a visceral distension paradigm was performed before first treatment and after treatment blocks. SPM8 was used to compare brain activity during painful and nonpainful visceral stimuli in regions associated with emotional arousal and interoception. Negative affect, anxiety symptoms and pain ratings were assessed. Results Eleven subjects completed the study and eight subjects provided fMRI data. AV608, compared with placebo, was associated with reduced anxiety, negative affect, and pain ratings. During AV608 treatment, the amygdala, hippocampus and anterior cingulate gyrus showed decreased activity during visceral distension. AV608 was also associated with decreases in activity in brain regions associated with interoception (posterior insula, anterior mid‐cingulate gyrus). Conclusions Chronic treatment with AV608 in IBS is associated with improved mood and pain ratings and activity of emotional arousal related brain regions. This suggests that further exploration of NK1R antagonists is warranted in visceral pain disorders, particularly in patients with comorbid anxiety symptoms.     

Safety,efficacy and costs of pharmacotherapy for functional gastrointestinal disorders: the case of alosetron and its implications

BACKGROUND: Functional gastrointestinal disorders cause substantial morbidity, but not mortality. Alosetron may achieve 'adequate relief ' in diarrhoea-predominant irritable bowel syndrome, but may cause major complications, including death. AIM: To appraise, quantitatively, the trade-off between possible symptomatic improvement and serious complications in the treatment of functional gastrointestinal disorders. METHODS: A decision analytical model was used to examine alosetron or standard treatment for 6 months in 45-year-old women with diarrhoea-predominant irritable bowel syndrome using the health care system's perspective. RESULTS: Assuming a 14% higher 'adequate relief' rate with alosetron compared to standard care, and a complication rate of four per 1000 persons in 6 months, alosetron gained 0.00081 quality-adjusted life-years (QALYs) per patient at a cost of 358,700 US dollars per QALY gained. Alosetron gained QALYs if 'adequate relief' increased the patients' utility by more than 0.01 in the base case. In probabilistic analysis, alosetron gained QALYs in 98.2% of iterations at a median cost of 212,600 US dollars per QALY (interquartile range, 138,000-338,900 US dollars per QALY). Results were highly sensitive to the utility gain with 'adequate relief' and alosetron's response and complication rates. CONCLUSIONS: Alosetron's benefit-to-risk profile appears to be favourable, but its cost per QALY gained may be substantial. Decision analyses on treatments for functional gastrointestinal disorders are likely to be highly sensitive to the utility estimates used. There is a pressing need for direct utility measurements in functional gastrointestinal disorders.