Antidepressants for functional gastrointestinal syndromes

Status of Brain Imaging in Gastroparesis

The pathophysiology of nausea and vomiting in gastroparesis is complicated and multifaceted involving the collaboration of both the peripheral and central nervous systems. Most treatment strategies and studies performed in gastroparesis have focused largely on the peripheral effects of this disease, while our understanding of the central nervous system mechanisms of nausea in this entity is still evolving. The ability to view the brain with different neuroimaging techniques has enabled significant advances in our understanding of the central emetic reflex response. However, not enough studies have been performed to further explore the brain–gut mechanisms involved in nausea and vomiting in patients with gastroparesis. The purpose of this review article is to assess the current status of brain imaging and summarize the theories about our present understanding on the central mechanisms involved in nausea and vomiting (N/V) in patients with gastroparesis. Gaining a better understanding of the complex brain circuits involved in the pathogenesis of gastroparesis will allow for the development of better antiemetic prophylactic and treatment strategies.

Comparison of paroxetine and amitriptyline in the treatment of refractory globus pharyngeus

BACKGROUND

Clinical trials of antidepressants for treatment of globus are generally rare, let alone for refractory globus pharyngeus.

AIMS

To illustrate the efficacy and side-effects of antidepressants between paroxetine and amitriptyline for refractory globus patients.

METHODS

Refractory globus patients were randomized into paroxetine group; amitriptyline group and lansoprazole group for 6-week treatment. All the subjects were asked to complete the following questionnaires pre- and post-therapy: Glasgow Edinburgh Throat Scale (GETS), Pittsburgh Sleep Quality Index, Hamilton Rating Scale Anxiety/Depression and Medical outcome short-form 36. Treatment response was defined as a >50% reduction in the GETS score.

RESULTS

One hundred and forty-eight patients completed the study. After 6 week treatment, 71.7% of paroxetine group (33/46) were calculated as treatment response, significantly higher than that in amitriptyline group (46.2%, 24/52) and lansoprazole group (14.0%, 7/50). Compared with lansoprazole group or amitriptyline group, a more distinct improvement of emotional well-being, quality of life and quality of sleep were observed in paroxetine group after 6-week treatment.

CONCLUSION

Paroxetine therapy is more efficacious than empirical high-dose antisecretory treatment, or even the low-dose amitriptyline therapy in alleviating globus symptoms, and producing global improvements for refractory globus patients.

The signaling of amitriptyline-induced inhibitory effect on electrical field stimulation response in colon smooth muscle

Amitriptyline, a well-known antidepressant, exerts inhibitory effect on electrically stimulated rat colon smooth muscle contraction. In this study, we investigated the signaling pathway of amitriptyline-induced inhibitory effect. Changes in isometric force of colon muscle were recorded on polygraph, and data were analyzed by measuring the inhibitory extent induced by amitriptyline. Firstly, muscles were contracted by stimulation with electric field stimulation (EFS), and then, amitriptyline was added cumulatively to determine its influence effect on EFS. Amitriptyline significantly inhibited EFS-induced contraction dose dependently. Then, the mechanism of inhibitory effect of amitriptyline was evaluated by pretreating with various antagonists such as L-NAME, methylene blue, atropine, 5-HT receptors blockers, guanethidine, prazosin, guanabenz, isoprenaline, Y27632 (Rho-kinase inhibitor), ML9 (myosin light chain kinase (MLCK) inhibitor), U73122 (PLC inhibitor), and chelerythrine (PKC inhibitor). Then, Ca(2+) channel blocker (nifedipine) and K(+)channel blockers, tetraethylammonium (TEA), 4-aminopyridine (4-AP), and glybenclamide, were used to determine the involvement of ion channels. L-NAME, guanabenz, 5HT4 receptor blocker, ML9, and Y27632 enhanced the effect of amitriptyline. Meanwhile, methylene blue, atropine, guanethidine, prazosin, methylsergide, ondansetron, U73122, and chelerythrine blocked its effect. It was also shown that nifedipine enhanced but TEA and glybenclamide blocked amitriptyline-induced inhibitory effect on EFS. Our results indicated that amitriptyline may exert inhibitory effect in response to EFS by inhibiting muscarinic receptors and then PLC-mediated PKC pathway leading to opening of ATP-sensitive potassium channel.

Effect of Amitriptyline and Escitalopram on Functional Dyspepsia: A Multicenter, Randomized Controlled Study

BACKGROUND & AIMS

Antidepressants are frequently prescribed to treat functional dyspepsia (FD), a common disorder characterized by upper abdominal symptoms, including discomfort or postprandial fullness. However, there is little evidence of the efficacy of these drugs in patients with FD. We performed a randomized, double-blind, placebo-controlled trial to evaluate the effects of antidepressant therapy on symptoms, gastric emptying (GE), and meal-induced satiety in patients with FD.

METHODS

We performed a study at 8 North American sites of patients who met the Rome II criteria for FD and did not have depression or use antidepressants. Patients (n = 292; 44 ± 15 years old, 75% were female, 70% with dysmotility-like FD, and 30% with ulcer-like FD) were randomly assigned to groups given placebo, 50 mg amitriptyline, or 10 mg escitalopram for 10 weeks. The primary end point was adequate relief of FD symptoms for ≥5 weeks of the last 10 weeks (of 12). Secondary end points included GE time, maximum tolerated volume in Nutrient Drink Test, and FD-related quality of life.

RESULTS

An adequate relief response was reported by 39 subjects given placebo (40%), 51 given amitriptyline (53%), and 37 given escitalopram (38%) (P = .05, after treatment, adjusted for baseline balancing factors including all subjects). Subjects with ulcer-like FD given amitriptyline were >3-fold more likely to report adequate relief than those given placebo (odds ratio = 3.1; 95% confidence interval: 1.1-9.0). Neither amitriptyline nor escitalopram appeared to affect GE or meal-induced satiety after the 10-week period in any group. Subjects with delayed GE were less likely to report adequate relief than subjects with normal GE (odds ratio = 0.4; 95% confidence interval: 0.2-0.8). Both antidepressants improved overall quality of life.

CONCLUSIONS

Amitriptyline, but not escitalopram, appears to benefit some patients with FD, particularly those with ulcer-like (painful) FD. Patients with delayed GE do not respond to these drugs. ClinicalTrials.gov ID: NCT00248651.

Effect of nortriptyline on symptoms of idiopathic gastroparesis: the NORIG randomized clinical trial

IMPORTANCE

Gastroparesis remains a challenging syndrome to manage, with few effective treatments and a lack of rigorously controlled trials. Tricyclic antidepressants are often used to treat refractory symptoms of nausea, vomiting, and abdominal pain. Evidence from well-designed studies for this use is lacking.

OBJECTIVE

To determine whether treatment with nortriptyline results in symptomatic improvement in patients with idiopathic gastroparesis.

DESIGN, SETTING, AND PARTICIPANTS

The NORIG (Nortriptyline for Idiopathic Gastroparesis) trial, a 15-week multicenter, parallel-group, placebo-controlled, double-masked, randomized clinical trial from the National Institute of Diabetes and Digestive and Kidney Diseases Gastroparesis Clinical Research Consortium (GpCRC), comparing nortriptyline with placebo for symptomatic relief in idiopathic gastroparesis. One hundred thirty patients with idiopathic gastroparesis were enrolled between March 2009 and June 2012 at 7 US academic medical centers. Patient follow-up was completed in October 2012. Inclusion criteria included delayed gastric emptying and moderate to severe symptom scores using the Gastroparesis Cardinal Symptom Index (GCSI). INTERVENTIONS Nortriptyline vs placebo. Study drug dose was increased at 3-week intervals (10, 25, 50, 75 mg) up to 75 mg at 12 weeks.

MAIN OUTCOMES AND MEASURES

The primary outcome measure of symptomatic improvement was a decrease from the patient's baseline GCSI score of at least 50% on 2 consecutive 3-week GCSI assessments during 15 weeks of treatment.

RESULTS

The primary symptomatic improvement outcome did not differ between 65 patients randomized to nortriptyline vs 65 patients randomized to placebo: 15 (23% [95% CI, 14%-35%]) in the nortriptyline group vs 14 (21% [95% CI, 12%-34%]) in the placebo group (P = .86). Treatment was stopped more often in the nortriptyline group (19 [29% {95% CI, 19%-42%}]) than in the placebo group (6 [9%] {95% CI, 3%-19%}]) (P = .007), but numbers of adverse events were not different (27 [95% CI, 18-39] vs 28 [95% CI, 19-40]) (P = .89).

CONCLUSIONS AND RELEVANCE

Among patients with idiopathic gastroparesis, the use of nortriptyline compared with placebo for 15 weeks did not result in improvement in overall symptoms. These findings do not support the use of nortriptyline for idiopathic gastroparesis.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00765895.

Functional Dyspepsia Treatment Trial (FDTT): a double-blind, randomized, placebo-controlled trial of antidepressants in functional dyspepsia, evaluating symptoms, psychopathology, pathophysiology and pharmacogenetics

BACKGROUND

Functional dyspepsia (FD) is a common problem affecting up to 10-25% of individuals. FD accounts for significant health care costs and affects quality of life but has no definitive treatment.

OBJECTIVES

The Functional Dyspepsia Treatment Trial (FDTT) aims to test whether treatment with an antidepressant (amitriptyline or escitalopram) leads to improvement of symptoms in patients with moderate to severe FD.

DESIGN

The FDTT is an international multicenter, parallel group, randomized, double-blind, placebo-controlled trial to evaluate whether 12 weeks of treatment with escitalopram or amitriptyline improves FD symptoms compared to treatment with placebo. Secondly, it is hypothesized that acceleration of solid gastric emptying, reduction of postprandial satiation, and enhanced gastric volume change with a meal will be significant positive predictors of short- and long-term outcomes for those on antidepressants vs. placebo. The third aim is to examine whether polymorphisms of GNβ3 and serotonin reuptake transporter influence treatment outcomes in FD patients receiving a tricyclic antidepressant, selective serotonin reuptake inhibitor therapy, or placebo.

METHODS

The FDTT enrollment began in 2006 and is scheduled to randomize 400 patients by the end of 2012 to receive an antidepressant or placebo for 12 weeks, with a 6-month post-treatment follow-up. The study incorporates multiple validated questionnaires, physiological testing, and specific genetic evaluations. The protocol was approved by participating centers' Institutional Review Boards and an independent Data Safety Monitoring Board was established for monitoring to ensure patient safety and a single interim review of the data in December 2010 (ClinicalTrials.gov number NCT00248651).

Efficacy of tricyclic antidepressant therapy in adults with cyclic vomiting syndrome: a two-year follow-up study

AIM

To investigate the effects of prolonged tricyclic antidepressants (TCAs) therapy on the frequency and duration of episodes of cyclic vomiting syndrome (CVS) in adults, and the global assessment of clinical improvement and the number of emergency department (ED) visits and/or hospitalizations.

METHOD

An open labeled study was conducted in adult CVS patients treated with a TCA and followed for up to 2 years. Demographic data, TCA dosage, duration and frequency of CVS episodes, ED visits, and hospitalizations at baseline and during TCA therapy were recorded, and patients were monitored for any adverse events.

RESULTS

Forty-six patients initially met the inclusion criteria and 41 patients (22 male) with mean age of 35 years (range: 18 to 63 y) on TCA were able to be followed for 1 year and 23 were evaluated for 2 years. Mean age of onset of CVS symptoms was 26 years (range: 10 to 52 y) and mean age for making the diagnosis of CVS was 32 years (range: 15 to 63 y). The frequency and duration of an episode and ED visits related to CVS were all significantly reduced after both the first and second year of TCA therapy (P<0.05). Eighty-eight percent reported an improved clinical status by subjective global assessment. Mild side effects were reported in 34% not necessitating stoppage of the TCA.

CONCLUSIONS

Long-term TCA therapy significantly reduces the frequency and duration of CVS episodes, ED visits, and hospitalizations (P<0.05), and improves overall clinical well-being providing evidence that they are effective therapy for adult CVS.

Effects of amitriptyline on gastric sensorimotor function and postprandial symptoms in healthy individuals: a randomized, double-blind, placebo-controlled trial

BACKGROUND

Low-dose tricyclic antidepressants have been used to treat chronic somatic and gastrointestinal pain disorders, including refractory functional dyspepsia. However, there are only limited data on the effects of these drugs on upper gastrointestinal function.

AIM

To compare the effects of two doses of amitriptyline (AMT) and placebo on gastric accommodation, emptying, satiation, and postprandial symptoms in healthy volunteers.

METHODS

Using a parallel-group, double-blind, placebo-controlled design, 41 healthy volunteers were randomized to AMT 25 mg, AMT 50 mg, or placebo for 2 wk. During the final 3 days of therapy, the following end points were assessed: fasting and postprandial gastric volumes, 2- and 4-h gastric emptying, time and volume to maximum satiation using a nutrient drink test, and postprandial symptoms 30 min later using 10-cm visual analog scales. AMT and metabolite levels were measured.

RESULTS

AMT slowed gastric emptying at 2 h (median 75% for placebo, 57% for AMT 25 mg, 67% for AMT 50 mg; P= 0.037) and 4 h (median 98% for placebo, 96% for AMT 25 mg, 92% for AMT 50 mg; P= 0.003). AMT did not affect gastric volumes or satiation volume, but it did reduce nausea scores at 30 min in a dose-dependent manner (median 2.1 for placebo, 0.9 for AMT 25 mg, and 0.0 for AMT 50 mg; P= 0.009).

CONCLUSION

In healthy volunteers, AMT slows gastric emptying of solids, but it does not significantly affect gastric volumes or satiation. AMT reduces nausea after challenge with a high calorie liquid load.

Updates on treatment of irritable bowel syndrome

Irritable bowel syndrome (IBS) is a highly prevalent gastrointestinal disorder characterized by abdominal pain and discomfort in association with altered bowel habits. It is estimated to affect 10%-15% of the Western population, and has a large impact on quality of life and (in)direct healthcare costs. IBS is a multifactorial disorder involving dysregulation within the brain-gut axis, and it is frequently associated with gastrointestinal motor and sensory dysfunction, enteric and central nervous system irregularities, neuroimmune dysregulation, and post-infectious inflammation. As with other functional medical disorders, the treatment for IBS can be challenging. Conventional therapy for those with moderate to severe symptoms is largely unsatisfactory, and the development of new and effective drugs is made difficult by the complex pathogenesis, variety of symptoms, and lack of objective clinical findings that are the hallmark of this disorder. Fortunately, research advances over the past several decades have provided insight into potential mechanisms responsible for the pathogenesis of IBS, and have led to the development of several promising pharmaceutical agents. In recent years there has been much publicity over several of these new IBS medications (alosetron and tegaserod) because of their reported association with ischemic colitis and cardiovascular disease. While these agents remain available for use under restricted prescribing programs, this highlights the need for continued development of safe and effective medication for IBS. This article provides a physiologically-based overview of recently developed and frequently employed pharmaceutical agents used to treat IBS, and discusses some non-pharmaceutical options that may be beneficial in this disorder.

Antidepressant therapy (imipramine and citalopram) for irritable bowel syndrome: a double-blind, randomized, placebo-controlled trial

BACKGROUND

The efficacy of antidepressants in irritable bowel syndrome (IBS) is controversial. No trials have directly compared a tricyclic with a selective serotonin reuptake inhibitor. Our aim was to determine whether imipramine and citalopram are efficacious in IBS.

METHODS

This was a randomized, double-blind, placebo-controlled, parallel group pilot trial with imipramine (50 mg) and citalopram (40 mg).

RESULTS

Of 51 IBS patients randomized, baseline characteristics were comparable among the treatment arms; the majority was diarrhea-predominant. Adequate relief of IBS symptoms (primary endpoint) was similar for each treatment arm. Improvements in bowel symptom severity rating for interference (P = 0.05) and distress (P = 0.02) were greater with imipramine versus placebo, but improvements in abdominal pain were not. There was a greater improvement in depression score (P = 0.08) and in the SF-36 Mental Component Score (P = 0.07), with imipramine. Citalopram was not superior to placebo. Approximately 20% of the variance in scores was explained by treatment differences for abdominal pain, bowel symptom severity disability, depression and the mental component of the SF-36.

CONCLUSION

Neither imipramine nor citalopram significantly improved global IBS endpoints over placebo.

Predictors of premature antidepressant discontinuation in functional gastrointestinal disorders

OBJECTIVES

To identify factors responsible for premature antidepressant discontinuation that would assist in designing management strategies for patients with functional gastrointestinal disorders. Antidepressants are being used increasingly to manage patients with functional gastrointestinal disorders; poor patient adherence to treatment regimens, particularly in the period shortly after antidepressant initiation, is common and interferes with success.

METHODS

Clinical records were reviewed from 172 outpatients who attended a university-based practice and who had been prescribed antidepressants to manage their functional gastrointestinal symptoms. Survival analysis methods were used to determine independent predictors of premature antidepressant discontinuation (within 6 months of initiation). Logistic regression analyses were used to see if the same predictors were responsible for side effects or poor treatment response.

RESULTS

Premature antidepressant discontinuation occurred in 41 (23.8%) subjects. Somatization features (state or trait) and history of depression or an anxiety disorder were the most significant predictors of premature discontinuation (p < or = .01 for each). Advancing age and female sex also were independent predictors (p < .05 for each). Somatization features and psychiatric illness were each linked to poor treatment response, whereas somatization features most consistently were associated with antidepressant side effects.

CONCLUSIONS

Failure to maintain treatment occurs in nearly a quarter of outpatients given antidepressants for functional gastrointestinal disorders. Somatization features and history of depression or anxiety most significantly interfered with treatment by predicting side effects, poor treatment response, and premature antidepressant discontinuation. Management algorithms should include specific strategies targeted at patients with these risk factors for poor treatment adherence.

Functional esophageal disorders

Functional esophageal disorders represent processes accompanied by typical esophageal symptoms (heartburn, chest pain, dysphagia, globus) that are not explained by structural disorders, histopathology-based motor disturbances, or gastroesophageal reflux disease. Gastroesophageal reflux disease is the preferred diagnosis when reflux esophagitis or excessive esophageal acid exposure is present or when symptoms are closely related to acid reflux events or respond to antireflux therapy. A singular, well-defined pathogenetic mechanism is unavailable for any of these disorders; combinations of sensory and motor abnormalities involving both central and peripheral neural dysfunction have been invoked for some. Treatments remain empirical, although the efficacy of several interventions has been established in the case of functional chest pain. Management approaches that modulate central symptom perception or amplification often are required once local provoking factors (eg, noxious esophageal stimuli) have been eliminated. Future research directions include further determination of fundamental mechanisms responsible for symptoms, development of novel management strategies, and definition of the most cost-effective diagnostic and treatment approaches.

Nonsurgical factors affecting symptomatic outcomes of antireflux surgery

A small number of patients will have persistent or new symptoms after antireflux surgery for gastroesophageal reflux disease (GERD). Most of these symptoms are due to recurrent reflux or some complication or side-effect of the operation. However, a few of these patients will be symptomatic without objective findings to explain these symptoms. The purpose of this review is to highlight potential non-surgical factors that may proceed to a poor symptomatic outcome after antireflux surgery. These factors include underlying esophageal pathophysiology, issues related to chronic pain and pain perception, personality and psychoemotional disorders, functional esophageal and/or bowel disorders, and the nocebo phenomenon. Awareness of these other causes can lead to more appropriate treatments.

Paroxetine for somatic pain associated with physical illness: a review

OBJECTIVE

The purpose of this article is to review the prevalence of somatic pain with and without depression or anxiety and the pharmacologic effects of the selective serotonin reuptake inhibitor paroxetine on pain in physical conditions with and without comorbid depression or anxiety.

DATA SOURCES

MEDLINE and PsychLIT/PsycINFO database. Keywords included depression, anxiety, pain, somatic, antidepressants, and paroxetine. Only English-language publications and abstracts were considered.

STUDY SELECTION

More than 100 articles that reflected the prevalence of somatic pain in patients with physical illness with and without comorbid depression or anxiety and that evaluated the efficacy of antidepressants in this population were identified and reviewed.

DATA SYNTHESIS

Nearly two thirds of patients with major depressive disorder suffer from a physical illness, and about one fifth of patients with chronic physical illness are depressed. Both of these comorbidities pose diagnostic and therapeutic challenges. Therapeutic effects of antidepressants on pain improvement in patients with chronic physical illnesses and comorbid depression/anxiety have been attributed to the antidepressant or anxiolytic properties of these drugs. However, tricyclic antidepressants have demonstrated analgesic properties in patients with physical illness both with and without depression. The review looks at evidence for the efficacy of the selective serotonin reuptake inhibitor paroxetine on pain in physical illness with and without depression and the mechanisms for the relief of pain and depression.

CONCLUSIONS

The efficacy of paroxetine for depression and anxiety comorbid with physical illness looks promising. Studies also allude to evidence linking the analgesic properties of paroxetine with its serotonergic and noradrenergic activity. Large randomized controlled trials within specific antidepressant classes and also comparing dualaction antidepressants are warranted that could shed some light on the unique advantage of paroxetine over other antidepressants.

Psychosocial assessment of functional gastrointestinal disorders in clinical practice

Functional gastrointestinal disorders are the most common conditions encountered in gastroenterology practice and are also commonly encountered in primary care. Psychosocial factors play an important role in these disorders (along with any chronic digestive disorder) by influencing healthcare seeking, illness behavior, symptom severity, quality of life, and digestive motility and sensation. Identification of relevant psychosocial factors in patients with chronic digestive disorders influences care and is a critical determinant of outcomes. This article provides a review of relevant psychosocial variables, assessment techniques, and therapeutic suggestions that can be of value in assessing patients with functional gastrointestinal disorders.

Open-label treatment with citalopram in patients with irritable bowel syndrome: a pilot study

BACKGROUND

This open-label pilot study investigated whether the selective serotonin reuptake inhibitor (SSRI) citalopram improves symptoms of irritable bowel syndrome (IBS), a functional gastrointestinal disorder with frequent psychiatric comorbidity.

METHOD

Fifteen patients meeting Rome I criteria for IBS were administered open-label citalopram (20-40 mg/day) for 12 weeks. The study was conducted from October 2000 to August 2001.

RESULTS

Twelve (80%) of the 15 subjects reported a > or = 50% decrease in the presence of abdominal pain, 10 (67%) reported a > or = 50% reduction in the severity of the symptom, and 12 (80%) reported a > or = 50% reduction in the frequency of the symptom. Approximately one half of the patients met criteria for remission (> or = 70% improvement) of abdominal pain.

CONCLUSION

Results of this pilot study suggest that large controlled trials are needed to further evaluate the efficacy of SSRIs such as citalopram for the treatment of IBS.

Diagnosis and treatment of noncardiac chest pain

Chest pain is common: one in four of the population have an episode annually. Of those who present to hospital, nearly two-thirds have noncardiac chest pain. More than half of these cases might have gastroesophageal reflux disease. Opinion differs over what is the most appropriate application of current investigatory methods. Evidence suggests that, once cardiac disease is ruled unlikely, empiric use of a proton pump inhibitor is an option; if acid suppression fails, detailed investigations as clinically indicated can be considered. A range of esophageal investigations is available, including 24-hour or 48-hour esophageal pH testing and esophageal manometry, as well as provocative tests, but there is no consensus as to which methods are the most useful. Psychiatric evaluation is not routine, but psychiatric or psychological disorders are common. Musculoskeletal disorders are also common, but are frequently overlooked. It is possible to subject patients to a comprehensive set of investigations before empiric therapy, but recent studies have failed to demonstrate an improved outcome using this exhaustive approach. A new tactic is required, with less attention spent on absolute diagnostic accuracy and more emphasis on optimizing the long-term clinical outcome in patients with noncardiac chest pain. It is possible that the targeted use of multiple drug trials in a policy of 'therapy as investigation' might be a superior methodology.

Management of esophageal symptoms following fundoplication

Laparoscopic antireflux surgery has emerged as a widely used and effective management option for the properly selected patient with gastroesophageal reflux disease. Poor symptomatic outcomes occur even in the best of hands, the most common being recurrent or persistent heartburn (or atypical symptoms) and dysphagia. When heartburn predominates, the initial management step is an anatomical and physiologic evaluation to determine whether acid reflux is controlled and if the postoperative neoanatomy is appropriate. If anatomical evaluation indicates surgical failure (eg, slipped or loose fundoplication, recurrent hiatal hernia), earlier re- operation may be warranted. Objective evidence of ongoing acid reflux or a reflux-symptom association despite anatomical integrity indicates reintroduction of antireflux medical therapy. Evidence favoring physiologic and anatomical success should direct treatment toward functional heartburn, including the use of tricyclic antidepressants. Dysphagia in the immediate postoperative setting mandates reassurance, as conservative measures alone often suffice while postoperative changes resolve. With persistent dysphagia, anatomical and physiologic evaluation is again indicated in the search for a mechanical-, motility-, or reflux-related symptom basis. Dilation techniques can prevent the need for re-operation, but persistent dysphagia associated with distorted postoperative anatomy will likely require surgical intervention. Regardless of the indication, re-operation carries substantial morbidity and reduced success rates compared with the initial procedure. These procedures mandate careful patient selection and referral to a center with thorough surgical experience.

Serotonergic modulation and irritable bowel syndrome

Irritable bowel syndrome (IBS) is a debilitating disease, which is characterised by recurrent abdominal cramping and pain, and is associated with either constipation and/or diarrhoea. It is approximately twice as prevalent in women as it is in men and is among the most common gastrointestinal (GI) disorders encountered in primary care. The aetiology of the disease is poorly understood but may include motility dysregulation, visceral sensitivity, inflammation, bacterial infection, dietary antigens, psychological stress, GI surgery or a gut-brain phenomenon. At present, there is no acceptable treatment for IBS, although recent advances indicate that some relief may be achieved by the administration of compounds that act on 5-HT (serotonin) receptors. This suggestion is the result of numerous studies which have shown that 5-HT may exert a number of diverse effects on human GI tissues. In addition, it has emerged that the levels of the 5-HT metabolite (5-HIAA) are raised in the plasma of IBS patients and that administration of 5-HT-like compounds may mimic the symptoms of IBS. It has therefore been proposed that therapy with compounds that act at 5-HT receptors will return the intestine to normal activity and alleviate the pain experienced by these patients. One compound (alosetron, a 5-HT3 receptor antagonist) has already been released onto the market but showed benefit in female patients only and only in those whose primary symptom was diarrhoea. In addition, the compound was recently withdrawn following concerns over its safety. The reasons why alosetron only appears to show efficacy in females, why these treatments are only effective in a subset of the population of IBS patients and why alosetron elicits its particular side effect profile have not been elucidated. One further serotonergic compound, tegaserod (Zelmac, a 5-HT4 receptor agonist), has shown promise for the treatment of patients with constipation-predominant IBS and is currently in pre-registration for this indication. It is clear, however, that further research will have to take place before the utility of serotonergic modulation in the treatment of IBS can be fully validated.

Usefulness of famotidine in functional dyspepsia patient treatment: comparison among prokinetic, acid suppression and antianxiety therapies

BACKGROUND

The treatment of functional dyspepsia is controversial.

AIM

The purpose of this paper is to clarify the initial effect of prokinetic, acid suppression and antianxiety treatment for functional dyspepsia patients.

PATIENTS AND METHODS

Sixty-four functional dyspepsia patients without Helicobacter pylori infection were randomly assigned to 15 mg/day of mosapride, 40 mg/day of famotidine, or 30 mg/day of tandospirone during an 8-week treatment. Individual functional dyspepsia symptoms were evaluated with 4 cm visual analogue scale before and at 2, 4 and 8 weeks after treatment.

RESULTS

Among 64 enrolled patients, 62 completed the study. Within 2 weeks, visual analogue scale score in the mosapride-treated group decreased from 2.29 +/-0.14 to 1.57 +/- 0.20; in the famotidine from 2.04 +/- 0.16 to 1.09 +/- 0.12 (mean +/- S.E.). Therefore, there were significant improvements of functional dyspepsia symptoms in mosapride- and famotidine-treated patients (P <0.01). Furthermore, famotidine was significantly more effective than mosapride (P < 0.05). On the contrary, visual analogue scale score in the tandospirone therapy was 2.23 +/- 0.20 and 2.13 +/- 0.22 before and at 2 weeks, respectively, without any significant improvement.

CONCLUSIONS

A treatment regimen of famotidine at 40 mg/day had a significant favourable effect on the clinical outcome in functional dyspepsia patients.

Functional Problems Following Esophageal Surgery

Functional problems following esophageal surgery for GERD are not infrequent. The majority of patients improve with time. Careful patient selection and attention to surgical technique are key factors in preventing such functional disorders. When anatomic abnormalities related to the fundoplication are identified, reoperation may offer symptom relief. Before embarking on re-fundoplication, a thorough preoperative evaluation of the esophageal physiology is recommended.

American Gastroenterological Association technical review on the diagnosis and treatment of gastroparesis

This literature review and the recommendations herein were prepared for the American Gastroenterological Association Clinical Practice Committee. The paper was approved by the Committee on May 16, 2004, and by the AGA Governing Board on September 23, 2004.

Management of Functional Abdominal Pain

The diagnosis of functional abdominal pain should be made based on the Rome II symptom criteria with only limited testing to exclude other disease. During physical examination the clinician may look for evidence of pain behavior which would be supportive of the diagnosis. Reassurance and proper education regarding the clinical entity of functional abdominal pain is critical for successful treatment and good patient satisfaction. Education should include validation that symptoms are real, and that other individuals experience similar symptoms. No further treatment may be required for those with mild symptoms. For patients with more severe symptoms, a long-term management plan of either pharmacological or psychological treatments is warranted. This will require a commitment by both the patient and the physician to engage in a partnership with active involvement and responsibility by both individuals. The goal of treatment--to decrease pain and increase function over time, not to cure the disorder-- should be explained. Strong consideration should be made for the use of an antidepressant to treat analgesic effects. Tricyclic antidepressants are the mainstay of therapy for functional pain disorders. The analgesic effect is generally quicker in onset and occurs at a lower dose than their effect on mood. To maximize patient compliance, patients should be told the rationale behind their use, warned of the potential side effects, and reassured that many of the side effects will disappear with time. Choice of an antidepressant should be based on the presence of concomitant symptoms (eg, depression), cost, and physician familiarity with specific agents. All patients with functional abdominal pain should be screened for underlying psychiatric disturbance as an untreated mood disorder will adversely affect response to treatment. If a concurrent mood disorder is found, it should be treated by either using a higher dose of the tricyclic antidepressant or by adding another antidepressant agent. Psychological interventions such as cognitive behavioral therapy may be important as adjuvant therapy or as an alternative to treatment with antidepressants for those patients who find antidepressants ineffective or are intolerant to them. Narcotics and benzodiazepines should not be used to treat chronic abdominal pain due to the high risk of physical and psychological dependence.

Effects of clonidine and tricyclic antidepressants on gastric smooth muscle contractility

To determine if and how clonidine and tricyclic antidepressants affect gastric contractility. Guinea pig fundic and antral circular muscle strips were studied in vitro. The effects of clonidine or amitriptyline added in graded concentrations on contractions to electric field stimulation (EFS), acetylcholine (ACh), and SP in the presence of N(epsilon)-nitro-l-arginine methyl ester (l-NAME) were studied. EFS produced frequency dependent contractions of fundic and antral muscle that were abolished by atropine or tetrodotoxin (TTX). ACh contractions were abolished by atropine but not TTX. Clonidine reduced contractile response to EFS but had no effect on ACh contractions. The threshold concentration of clonidine to inhibit EFS contractions was lower in the fundus than in the antrum. Amitriptyline reduced contractions to both EFS and ACh but not to SP. The threshold concentration of amitriptyline to inhibit EFS contractions was lower in the antrum than in the fundus. Both clonidine and amitriptyline affect gastric contractility. At threshold concentrations, clonidine affects fundic contractility whereas amitriptyline affects antral contractility. Clonidine affects gastric contractility in response to EFS but not to ACh, suggesting alpha-2 receptors on cholinergic nerves that reduce ACh release. Amitriptyline inhibits gastric contractility to EFS and ACh suggesting an inhibitory muscle effect.

Advances in the management of irritable bowel syndrome

Irritable bowel syndrome (IBS) is a commonly encountered condition seen in multiple medical specialties. Recent research has brought dramatic advances in our understanding of the epidemiology, burden of illness, diagnosis, and management of IBS. It is now widely accepted that the prevalence of IBS is between 10% and 20% of the US population and that the direct and indirect costs associated with IBS are significant. The processes required for diagnosis of IBS remain controversial. Scant evidence exists to support exhaustive diagnostic evaluations, and IBS is no longer considered a diagnosis of exclusion. The use of standardized symptom-based criteria remains to be perfected, and the diagnosis is often arrived at only after multiple laboratory, endoscopic, and radiologic examinations. The effects of treatment for IBS mirror the heterogeneous nature of the condition. No single medication has proven to be universally effective, and multiple therapeutic approaches exist. Greater understanding of gastrointestinal neurophysiology has led to promising advances in medical and nonmedical approaches to IBS.

New approaches to the medical treatment of irritable bowel syndrome

Irritable bowel syndrome (IBS) is a common disorder with a worldwide distribution; it is characterized by abdominal pain and discomfort associated with an alteration of bowel function. The treatment approach for IBS depends on the patient's presenting symptoms at the time of diagnosis, and treatment is usually directed toward the predominant symptom. In this review we discuss the current approach to the treatment of IBS.

Cognitive-behavioral therapy versus education and desipramine versus placebo for moderate to severe functional bowel disorders

BACKGROUND & AIMS

Studies of antidepressants and psychological treatments in functional bowel disorders (FBD) are methodologically limited. The aim of this study was to assess the clinical efficacy and safety of cognitive-behavioral therapy (CBT) against education (EDU) and desipramine (DES) against placebo (PLA) in female patients with moderate to severe FBD (irritable bowel syndrome, functional abdominal pain, painful constipation, and unspecified FBD). We also evaluated the amenability of clinically meaningful subgroups to these treatments.

METHODS

This randomized, comparator-controlled, multicenter trial enrolled 431 adults from the University of North Carolina and the University of Toronto with moderate to severe symptoms of FBD. Participants received psychological (CBT vs. EDU) or antidepressant (DES vs. PLA) treatment for 12 weeks. Clinical, physiologic, and psychosocial assessments were performed before and at the end of treatment.

RESULTS

The intention-to-treat analysis showed CBT as significantly more effective than EDU (P = 0.0001; responder rate, 70% CBT vs. 37% EDU; number needed to treat [NNT ], 3.1). DES did not show significant benefit over PLA in the intention-to-treat analysis (P = 0.16; responder rate, 60% DES vs. 47% PLA; NNT, 8.1) but did show a statistically significant benefit in the per-protocol analysis (P = 0.01; responder rate, 73% DES vs. 49% PLA; NNT, 5.2), especially when participants with nondetectable blood levels of DES were excluded (P = 0.002). Improvement was best gauged by satisfaction with treatment. Subgroup analyses showed that DES was beneficial over PLA for moderate more than severe symptoms, abuse history, no depression, and diarrhea-predominant symptoms; CBT was beneficial over EDU for all subgroups except for depression.

CONCLUSIONS

For female patients with moderate to severe FBD, CBT is effective and DES may be effective when taken adequately. Certain clinical subgroups are more or less amenable to these treatments.

Brain responses to visceral and somatic stimuli in patients with irritable bowel syndrome with and without fibromyalgia

OBJECTIVE

Symptoms of irritable bowel syndrome (IBS) and fibromyalgia (FM) commonly coexist. We hypothesized that one of the mechanisms underlying this comorbidity is increased activation of brain regions concerned with the processing and modulation of visceral and somatic afferent information, in particular subregions of the anterior cingulate cortex (ACC).

METHODS

Regional cerebral blood flow (rCBF) was assessed in age-matched female IBS (n = 10) and IBS + FM (n = 10) subjects using H(2)(15)O positron emission tomography during noxious visceral (rectal) and somatic pressure stimuli.

RESULTS

GI symptom severity was significantly higher in the IBS patients compared with the IBS + FM patients (p < 0.05). In addition, IBS + FM patients rated somatic pain as more intense than their abdominal pain (p < 0.05). Whereas the somatic stimulus was less unpleasant than the visceral stimulus for IBS patients without FM, the somatic and visceral stimuli were equally unpleasant in the IBS + FM group. Group differences in regional brain activation were entirely within the middle subregion of the ACC. There was a greater rCBF increase in response to noxious visceral stimuli in IBS patients and to somatic stimuli in IBS + FM patients.

CONCLUSION

Chronic stimulus-specific enhancement of ACC responses to sensory stimuli in both syndromes may be associated with cognitive enhancement of either visceral (IBS) or somatic (IBS + FM) sensory input and may play a key pathophysiologic role in these chronic pain syndromes.

Noncardiac chest pain: evaluation and treatment

Noncardiac chest pain is a heterogeneous condition for which diagnosis and treatment are challenging. Research is needed to streamline evaluation to minimize unnecessary invasive testing and costs. Chest pain clinics to assess chest pain patients are popular in the United States and may be of value in reassuring patients and reducing presentation to hospital; however, recently this has been contended [111]. Options for the effective treatment of NCCP are dependent on the risk of an adverse outcome and the cost-effectiveness of the management algorithm that is followed. Most (64%) of those presenting to the emergency department with chest pain are classified as having NCCP [112,113]. GERD is probably the most important cause and application of a test of acid suppression with a high-dose PPI for 1 to 2 weeks seems to be a useful diagnostic tool. In those patients with GERD-related NCCP, short-term and potentially long-term therapy with a PPI (commonly higher than standard dose) is required to alleviate symptoms. Esophageal dysmotility is relatively uncommon in patients with NCCP and evaluation by esophageal manometry might be limited to rule out achalasia. Chest wall syndromes are common but probably often missed. Many patients with NCCP have psychologic or psychiatric abnormalities, as either the cause or an effect of the chest pain, but diagnosis here depends on techniques not applied easily in the acute situation. Pain modulators seem to offer significant improvement in chest pain symptoms for non-GERD-related NCCP. Finally, trials of management strategies to deal with this problem are required urgently, because the earlier discharge of patients with NCCP may exacerbate the problem. Fig. 2 provides a flow chart for diagnosis and treatment of NCCP.

Functional dyspepsia: evaluation and treatment

Functional dyspepsia is one of the most common disorders seen in general practice and by gastroenterologists. New concepts regarding the pathophysiology and its role for the symptom pattern have emerged during the last few years. This is of importance for development of new treatment alternatives in the near future. At the moment, however, empirical treatment with acid-suppressive agents and prokinetics is the recommended therapeutic approach in the management of these patients, despite limited efficacy. Identification and treatment of H pylori infection has been recommended for uninvestigated dyspepsia, because it may cure underlying peptic ulcer disease, but is unlikely to provide symptomatic benefit to patients with functional dyspepsia. Refractory patients may respond to antidepressants or to psychologic treatments, but proof of efficacy is limited. New and more effective approaches are badly needed for functional dyspepsia.

Comorbidity of irritable bowel syndrome in psychiatric patients: a review

Irritable bowel syndrome (IBS), a functional gastrointestinal disorder, is present in 10% to 20% of the U.S. adult population. The syndrome is best defined as chronic abdominal discomfort with changes in stool frequency, consistency, and passage, with associated symptoms such as abdominal bloating or presence of mucus in stools. Several studies have shown that up to 70% to 90% of patients with IBS who seek treatment have psychiatric comorbidity, most notably mood and anxiety disorders. Recent studies have shown a high prevalence of IBS in psychiatric patients who seek treatment, with a prevalence of 19% in schizophrenia, 29% in major depression, and 46% in panic disorder among other disorders. Our article reviews the comorbidity of IBS in psychiatric patients and discusses implications for treatment.

Selective effects of serotonergic psychoactive agents on gastrointestinal functions in health

This study evaluated the effects of serotonergic psychoactive agents on gastrointestinal functions in healthy human subjects. Participants received one of four regimens in a randomized, double-blind manner: buspirone, a 5-HT(1A) receptor agonist (10 mg twice daily); paroxetine, a selective serotonin reuptake inhibitor (20 mg daily); venlafaxine-XR, a selective serotonin and norepinephrine reuptake inhibitor (75 mg daily); or placebo for 11 days. Physiological testing performed on days 8-11 included scintigraphic assessment of gastrointestinal and colonic transit, the nutrient drink test, and assessment of the postprandial change in gastric volume. Fifty-one healthy adults (40 females, 11 males) participated in this study. No effects on gastric emptying or colonic transit were identified with any agent. Small bowel transit of a solid meal was accelerated by paroxetine. Buspirone decreased postprandial aggregate symptom and nausea scores. Venlafaxine-XR increased the postprandial change in gastric volume. Buspirone, paroxetine, and venlafaxine-XR affect upper gastrointestinal functions in healthy humans. These data support the need for clinical and physiological studies of these agents in functional gastrointestinal disorders.

Irritable Bowel Syndrome

Because treatment of irritable bowel syndrome (IBS) patients can be frustrating to the clinician and patient as well, the physician should strive to gain the patient's confidence with a concise, appropriate work-up and by offering reassurance and education that IBS is a functional disorder without significant long-term health risks. First-line treatment should be aimed at treating the most bothersome symptom. Tricyclic antidepressants are superior to placebo in reducing abdominal pain scores, as well as improving global symptom severity. Loperamide is superior to placebo in managing IBS-associated diarrhea. Whereas fiber has a role in treating constipation, its value for IBS or, specifically, in the relief of abdominal pain or diarrhea associated with IBS is controversial. Although certain antispasmodics have demonstrated superiority over placebo in managing abdominal pain, none of these agents are available in the United States. Probiotic therapy using Lactobacillus plantarum has demonstrated superiority to placebo in improving pain, regulating bowel habits, and decreasing flatulence. As studied in a recent placebo-controlled prospective study, Chinese herbal medicines significantly improved bowel symptom scores and global symptom profile, and reduced IBS-related quality of life impairment. Some of the most promising emerging therapies in IBS revolve around targeted pharmacotherapeutic modulation of serotonin receptors (ie, 5-HT3 and 5-HT4 subtypes), which are involved in sensory and motor functions of the gut. Other investigational agents that are also being explored include cholecystokinin antagonists, alpha2-adrenergic agonists (eg, clonidine), serotonin reuptake inhibitors (eg, citalopram), and neurokinin antagonists. IBS is best understood through the biopsychosocial paradigm, and therefore, its effective management requires a comprehensive multidisciplinary approach based on patient education and reassurance, enhanced by diet recommendations and lifestyle modifications, and complemented by pharmacotherapy and psychosocial intervention in more severe cases.

Effect of the selective serotonin reuptake inhibitor sertraline on gastric sensitivity and compliance in healthy humans

Abstract Visceral hypersensitivity may contribute to symptoms in functional dyspepsia. Selective serotonin reuptake inhibitors (SSRIs) may be beneficial in functional gastrointestinal disorders. The aim of this study was to determine whether the SSRI sertraline affects gastric sensitivity and compliance in healthy humans. Ten healthy humans completed a 6-week randomized, double-blind, crossover trial of sertraline (50 mg day(-1)) vs. placebo. After each 2-week treatment, fullness, pain and nausea were rated at increasing gastric barostat distending pressures. Sensation thresholds above minimal distending pressure (MDP) were determined with a tracking method. Somatic sensory testing was performed by hand immersion in ice water. No differences were found between sertraline and placebo for symptoms as a function of distending pressure (fullness, P = 0.72; pain, P = 0.79; nausea, P = 0.41), gastric compliance (P = 0.15), median and interquartile range thresholds for first sensation [4.1 (3.5-5.7) vs. 6.2 (3.3-10.0) mmHg above MDP, P = 0.19] and pain [15.2 (8.3-21.0) vs. 15.3 (10.3-19.8) mmHg above MDP, P = 0.85], and median tolerance times for hand ice water immersion [27 (19-99) vs. 29 (20-180) s, P = 0.73]. In conclusion, sertraline had no effect on gastric sensitivity or compliance, or somatic pain tolerance in healthy humans. Studies are needed to assess the effects of SSRIs on visceral sensation and clinical symptoms in patients with functional dyspepsia.

Clinical perspectives, mechanisms, diagnosis and management of irritable bowel syndrome

This consensus document reviews the current status of the epidemiology, social impact, patient quality of life, pathophysiology, diagnosis and treatment of irritable bowel syndrome. Current evidence suggests that two major mechanisms may interact in irritable bowel syndrome: altered gastrointestinal motility and increased sensitivity of the intestine. However, other factors, such as psychosocial factors, intake of food and prior infection, may contribute to its development. Management of patients is based on a positive diagnosis of the symptom complex, careful history and physical examination to exclude 'red flags' as risk factors for organic disease, and, if indicated, investigations to exclude other disorders. Therapeutic choices include dietary fibre for constipation, opioid agents for diarrhoea and low-dose antidepressants or infrequent use of antispasmodics for pain, although the evidence basis for efficacy is limited or in some cases absent. Psychotherapy and hypnotherapy are the subject of ongoing study. Treatment should be tailored to patient needs and fears. Novel therapies are emerging, and drugs acting on serotonin receptors have proven efficacy and a scientific rationale and, if approved, should be useful in the overall management of patients with irritable bowel syndrome. Patient and physician education, early identification of psychosocial issues and better therapies are important strategies to reduce the suffering and societal cost of irritable bowel syndrome.

Psychotropic agents in irritable bowel syndrome

The use of antidepressants to treat patients with irritable bowel syndrome (IBS) has been extended in recent years because of their possible neuromodulatory and analgesic effects, generally in doses that do not have antidepressant effects. There seems to be sufficient evidence to support the recommendation that psychotropic agents may be effective in two clinical scenarios that are not mutually exclusive. The first is in patients with IBS who have pain and related symptoms that are unresponsive to medical therapy. The second is in patients with IBS who have concomitant psychologic dysfunction. This article reviews the evidence to support these recommendations and guidelines, which may be used to optimize medical management in these patients.

The economic impact of irritable bowel syndrome in a managed care setting

GOALS

To compare the healthcare resource consumption of patients who have irritable bowel syndrome (IBS) with an age-, gender-, and comorbidity-matched cohort of patients without IBS from a managed care perspective.

STUDY

Retrospective cohort analysis. Data were obtained electronically through the Henry Ford Health System corporate data warehouse. Patients with IBS were eligible if they had at least one primary diagnosis of irritable colon (ICD-9-CM 564.1). The control cohort was identified from an age, gender, and comorbidity population-matched (5:1) sample. The index date for the IBS and control cohorts was defined as the first initial diagnosis and first clinical encounter in 1998, respectively. The charges per patient by resource use type were collected for the 12 months before and after the index date.

RESULTS

A total of 501 patients with IBS and 2505 controls fulfilled the inclusion and exclusion criteria (70% female, 58% between 40 and 65 years). The IBS cohort, before the IBS diagnosis, had significantly higher total charges (p < 0.001), drug charges (p < 0.001), and outpatient charges (p < 0.001) than the control cohort. During the postindex (postdiagnosis period), the patients with IBS had higher total charges (p < 0.006), outpatient charges (p < 0.022), and drug charges (p < 0.001) than the control population. The control cohort had higher procedure charges (p < 0.001) during both periods.

CONCLUSIONS

Patients with an IBS diagnosis represent a substantial cost to managed care before and after the diagnosis of IBS. Costs associated with these patients result mainly from non-IBS conditions. Further research is warranted to identify these patients earlier, and to prevent the economic burden associated with them.

Functional (Nonulcer) Dyspepsia

Functional (nonulcer) dyspepsia refers to upper abdominal pain or discomfort with or without symptoms of early satiety, nausea, or vomiting with no definable organic cause. The current Rome II criteria help to diagnose functional dyspepsia and avoid misdiagnosis of gastroesophageal reflux disease and irritable bowel syndrome as functional dyspepsia. Assessment of gastric emptying with scintigraphy or breath testing may be useful in identifying delayed gastric emptying in patients with dyspeptic symptoms and may be helpful in patient management. Electrogastrography is a noninvasive test that evaluates for gastric dysrhythmias. Satiety testing is being evaluated as an indirect test for impaired fundic relaxation and visceral hypersensitivity. The symptom response to Helicobacter pylori therapy in patients with functional dyspepsia and a negative endoscopy examination but a positive H. pylori test is marginal. Lifestyle modifications often are suggested for initial treatment of functional dyspepsia. Dietary changes such as frequent small meals, low-fat diet, and avoidance of certain aggravating foods may improve symptoms. Additional measures include cessation of smoking, avoiding excess alcohol intake, and minimizing coffee intake. Antacids and over-the-counter histamine type 2 receptor antagonists may be helpful as an "on-demand" therapy for intermittent symptoms. They are safe and relatively inexpensive. Different subgroups of functional dyspepsia are based on the predominant symptom and may help in choosing an appropriate drug to initiate therapy. If the predominant symptom is epigastric pain (ulcer-like functional dyspepsia), histamine-2 receptor antagonists or proton pump inhibitors are the initial treatment of choice. If fullness, bloating, early satiety or nausea is the predominant complaint (dysmotility-like functional dyspepsia), a prokinetic agent may help. Metoclopramide is the only available effective prokinetic agent at present. If metoclopramide is used, short-term treatment and discussion of possible side effects with the patient are advised. If there is no response to these initial treatments, switching therapy from proton pump inhibitor to prokinetic or vice versa can be tried. If these treatment options fail, patient re-evaluation for other disorders (including other functional bowel disorders) is advised. A low-dose tricyclic antidepressant at bedtime may be helpful for treatment of visceral hypersensitivity.

Effects of tachykinin NK1 receptor antagonists on the viscerosensory response caused by colorectal distention in rabbits

Irritable bowel syndrome (IBS) is a common disorder mainly characterized by altered bowel habits and visceral pain. In this study, we investigated the role of tachykinin NK1 receptors in the visceral pain response (abdominal muscle contraction) caused by colorectal distention in rabbits previously subjected to colonic irritation, using the selective tachykinin NK1 receptor antagonists TAK-637 [(aR,9R)-7-[3,5-Bis(trifluoromethyl)benzyl]-8,9,10,11-tetrahydro-9-methyl-5-(4-methylphenyl)-7H-[1,4] diazocino[2,1-g][1,7]naphthyridine-6,13-dione] and (+/-)-CP-99,994 (+/-)-(2S,3S)-3-(2-methoxybenzylamino)-2-phenylpiperidine. Intracolorectal administration of 0.8% acetic acid solution enhanced the nociceptive response to colorectal distention, producing a significant increase in the number of abdominal muscle contractions. Under these conditions, intraduodenal TAK-637 (0.1-3 mg/kg) dose dependently decreased the number of distention-induced abdominal contractions, and a significant inhibitory effect was observed with doses of 0.3 to 3 mg/kg. Another tachykinin NK1 antagonist, (+/-)-CP-99,994, also reduced the number of abdominal contractions. In contrast, the enantiomer of TAK-637 (which has very weak tachykinin NK1 receptor antagonistic activity), trimebutine maleate, ondansetron, and atropine sulfate did not inhibit the abdominal response. The main metabolite of TAK-637, which has more potent tachykinin NK1 receptor antagonistic activity but permeates the central nervous system less well than TAK-637, produced less inhibition of the viscerosensory response. When given intrathecally, TAK-637 and (+/-)-CP-99,994 markedly reduced the number of abdominal contractions. These results suggest that tachykinin NK1 receptors play an important role in mediating visceral pain and that TAK-637 inhibits the viscerosensory response to colorectal distention by antagonizing tachykinin NK1 receptors, mainly in the spinal cord. They also suggest that TAK-637 may be useful in treating functional bowel disorders such as IBS.