Psychotropic agents in irritable bowel syndrome

Bulking agents, antispasmodics and antidepressants for the treatment of irritable bowel syndrome

BACKGROUND

Irritable bowel syndrome (IBS) is a common chronic gastrointestinal disorder. The role of pharmacotherapy for IBS is limited and focused mainly on symptom control.

OBJECTIVES

The objective of this systematic review was to evaluate the efficacy of bulking agents, antispasmodics and antidepressants for the treatment of irritable bowel syndrome.

SEARCH STRATEGY

Computer assisted structured searches of MEDLINE, EMBASE, The Cochrane library, CINAHL and PsychInfo were conducted for the years 1966-2009. An updated search in April 2011 identified 10 studies which will be considered for inclusion in a future update of this review.

SELECTION CRITERIA

Randomized controlled trials comparing bulking agents, antispasmodics or antidepressants with a placebo treatment in patients with irritable bowel syndrome aged over 12 years were considered for inclusion. Only studies published as full papers were included. Studies were not excluded on the basis of language. The primary outcome had to include improvement of abdominal pain, global assessment or symptom score.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data from the selected studies. Risk Ratios (RR) and Standardized Mean Differences (SMD) with 95% confidence intervals (CI) were calculated. A proof of practice analysis was conducted including sub-group analyses for different types of  bulking agents, spasmolytic agents or antidepressant medication. This was followed by a proof of principle analysis where only the studies with adequate allocation concealment were included.

MAIN RESULTS

A total of 56 studies (3725 patients) were included in this review. These included 12 studies of bulking agents (621 patients), 29 of antispasmodics (2333 patients), and 15 of antidepressants (922 patients). The risk of bias was low for most items. However, selection bias is unclear for many of the included studies because the methods used for randomization and allocation concealment were not described. No beneficial effect for bulking agents over placebo was found for improvement of abdominal pain (4 studies; 186 patients; SMD 0.03; 95% CI -0.34 to 0.40; P = 0.87), global assessment (11 studies; 565 patients; RR 1.10; 95% CI 0.91 to 1.33; P = 0.32) or symptom score (3 studies; 126 patients SMD -0.00; 95% CI -0.43 to 0.43; P = 1.00). Subgroup analyses for insoluble and soluble fibres also showed no statistically significant benefit. Separate analysis of the studies with adequate concealment of allocation did not change these results. There was a beneficial effect for antispasmodics over placebo for improvement of abdominal pain (58% of antispasmodic patients improved compared to 46% of placebo; 13 studies; 1392 patients; RR 1.32; 95% CI 1.12 to 1.55; P < 0.001; NNT = 7), global assessment (57% of antispasmodic patients improved compared to 39% of placebo; 22 studies; 1983 patients; RR 1.49; 95% CI 1.25 to 1.77; P < 0.0001; NNT = 5) and symptom score (37% of antispasmodic patients improved compared to 22% of placebo; 4 studies; 586 patients; RR 1.86; 95% CI 1.26 to 2.76; P < 0.01; NNT = 3). Subgroup analyses for different types of antispasmodics found statistically significant benefits for cimteropium/ dicyclomine, peppermint oil, pinaverium and trimebutine. Separate analysis of the studies with adequate allocation concealment found a significant benefit for improvement of abdominal pain. There was a beneficial effect for antidepressants over placebo for improvement of abdominal pain (54% of antidepressants patients improved compared to 37% of placebo; 8 studies; 517 patients; RR 1.49; 95% CI 1.05 to 2.12; P = 0.03; NNT = 5), global assessment (59% of antidepressants patients improved compared to 39% of placebo; 11 studies; 750 patients; RR 1.57; 95% CI 1.23 to 2.00; P < 0.001; NNT = 4) and symptom score (53% of antidepressants patients improved compared to 26% of placebo; 3 studies; 159 patients; RR 1.99; 95% CI 1.32 to 2.99; P = 0.001; NNT = 4). Subgroup analyses showed a statistically significant benefit for selective serotonin releasing inhibitors (SSRIs) for improvement of  global assessment and for tricyclic antidepressants (TCAs) for improvement of abdominal pain and symptom score. Separate analysis of studies with adequate allocation concealment found a significant benefit for improvement of symptom score and global assessment. Adverse events were not assessed as an outcome in this review.

AUTHORS' CONCLUSIONS

There is no evidence that bulking agents are effective for treating IBS.  There is evidence that antispasmodics are effective for the treatment of IBS. The individual subgroups which are effective include: cimetropium/dicyclomine, peppermint oil, pinaverium and trimebutine. There is good evidence that antidepressants are effective for the treatment of IBS. The subgroup analyses for SSRIs and TCAs are unequivocal and their effectiveness may depend on the individual patient. Future research should use rigorous methodology and valid outcome measures.

Centrally acting therapies for irritable bowel syndrome

Irritable bowel syndrome (IBS) and other functional gastrointestinal (GI) disorders typically defy traditional diagnostic methods based on structural abnormalities, and has led to the emergence of the discipline of neurogastroenterology or the study of the "brain-gut axis," which is based on dysregulation of neuroenteric pathways as a key pathophysiological feature of IBS. Centrally acting treatments can influence these pathways and improve the clinical manifestations of pain and bowel dysfunction associated with this disorder. To successfully implement these treatment strategies, it is important to recognize their dual effects on brain and gut, understanding the nature and severity of the GI symptoms and their psychosocial concomitants, and applying them within the context of the patient's understanding of their value.

Neuroimmune interaction in inflammatory diseases

The inflammatory response is modulated through interactions among the nervous, endocrine, and immune systems. Intercommunication between immune cells and the autonomic nervous system is a growing area of interest. Spatial and temporal information about inflammatory processes is relayed to the central nervous system (CNS) where neuroimmune modulation serves to control the extent and intensity of the inflammation. Over the past few decades, research has revealed various routes by which the nervous system and the immune system communicate. The CNS regulates the immune system via hormonal and neuronal pathways, including the sympathetic and parasympathetic nerves. The immune system signals the CNS through cytokines that act both centrally and peripherally. This review aims to introduce the concept of neuroimmune interaction and discuss its potential clinical application, in an attempt to broaden the awareness of this rapidly evolving area and open up new avenues that may aid in the treatment of inflammatory diseases.

Irritable bowel syndrome in psychiatric perspectives: a comprehensive review

We comprehensively reviewed the irritable bowel syndrome (IBS) in terms of pathogenesis, psychiatric implications, general management and appropriate role of antidepressants, in particular selective serotonin uptake inhibitors (SSRIs) in the treatment of IBS. English language papers cited in MEDLINE and PychInfo from January 2000 to July 2006 were searched with a combination of the following key words: irritable bowel syndrome, 5-HT, pathogenesis, comorbid, psychiatry, treatment, psychotropic drugs, antidepressant, selective serotonin reuptake inhibitors (fluoxetine, paroxetine, sertraline, fluvoxamine, citalopram and sertraline), tricyclic antidepressants, review, meta-analysis and placebo. The papers on IBS describing the clinical features, pathophysiology, evaluation, management, and clinical trials [randomised placebo-controlled trial (RCT), open-label study or case report] were selected for this review. Further literatures were also detected from references of the identified papers. The epidemiology, diagnostic criteria, pathophysiology, general management, bidirectional comorbidity, summary of currently available RCTs and open-label studies investigating antidepressant efficacy (focusing on SSRIs), and suggestions for SSRI use in IBS were relevantly synthesised based on through review of identified data. This article summarised an up-to-date clinical overview of IBS in psychiatric perspectives as well as to position a current role of SSRIs in the treatment of IBS. From this review, the routine use of SSRIs for IBS treatment cannot be conclusive due to a paucity of RCTs, although a handful of RCTs suggested a potentially beneficial effect of SSRIs over placebo.

Controversies concerning pathophysiology and management of acalculous biliary-type abdominal pain

Acalculous biliary-type abdominal pain is a commonly encountered clinical problem whose pathophysiology is unclear and evaluation and management are controversial. Cholecystokinin cholescintigraphy to measure the gallbladder ejection fraction (GEF) has been advocated as a criterion for cholecystectomy. However, there is no consensus regarding the dose and rate of infusion of cholecystokinin, both of which can alter the GEF, and the definition of an abnormal ejection fraction varies among studies. Many but not all studies have concluded that a low GEF predicts good outcomes after cholecystectomy, but most studies suffer from poor methodology and there is only one prospective randomized controlled trial. Also, some patients with a normal GEF have responded to cholecystectomy. Another controversial area has been the role of sphincter of Oddi dysfunction (SOD) in patients with biliary-type pain and gallbladder in situ. Some reports suggest an overlap between SOD and low GEF, although a causal relationship has not been established. Yet another subject of interest is the role of visceral hyperalgesia in patients with acalculous biliary-type pain. We have reviewed the relevant literature relating to these issues and have highlighted the controversial aspects. In the absence of high-quality studies, an evidence-based treatment algorithm is difficult to design but will be proposed. More prospective controlled trials are warranted to better define the appropriate evaluation and management of patients with this syndrome.

Clinical response to tricyclic antidepressants in functional bowel disorders is not related to dosage

BACKGROUND

As shown in the per protocol analysis of a recent randomized, controlled trial, when tolerated, Desipramine (DES) is effective over placebo (PLA) in treating moderate-to-severe functional bowel disorders (FBD). Clinical experience suggests that the benefit from tricyclic antidepressants (TCA) in FBD can be achieved at doses lower than those used to treat major depression. Within psychiatry, when using higher dosage of TCAs, plasma levels can be used to adjust daily dosage to optimize a treatment response. However, in FBD, it is not known whether plasma levels at the lower dosage are similarly related to a clinical response.

AIM

To determine in treating FBD, whether DES blood levels or dose taken can predict a clinical response.

METHODS

As part of a study of 12 wk of antidepressant and psychological treatment in 431 patients with FBD at UNC and U of Toronto, we studied those participants who completed treatment (per protocol analysis) taking DES (N = 97, dose 50-150 mg/day) or pill placebo (PLA) (N = 55 1-3 pills/day). The primary outcome measure was defined as a composite score (Satisfaction with Treatment, McGill Pain Questionnaire, Global Well-being, and IBS-QOL). The composite score was correlated with: (i) DES plasma levels at week 6, and (ii) number of pills taken over the duration of the 12-wk treatment period. In addition, we also compared DES dose with DES plasma levels.

RESULTS

There was a modest correlation between mean DES dose at weeks 5 and 6 and DES blood level at week 6 (R = 0.2 p < 0.07). However, there were no significant correlations between the composite score either with DES dose or with DES blood levels.

CONCLUSIONS

Detectable blood levels of DES are associated with a clinical response in FBD. However, with dosages up to 150 mg, there is no relationship between total dose or plasma level and the clinical response.

Options for patients with irritable bowel syndrome: contrasting traditional and novel serotonergic therapies

This article reviews the efficacy and tolerability of traditional therapies for irritable bowel syndrome (IBS) and concludes that they are limited by both poor efficacy and adverse effects. Serotonin, a neurotransmitter found mainly in the gut, appears to represent a link in IBS pathophysiological processes -- altered gut motility, abnormal intestinal secretion and visceral hypersensitivity. Recently, available treatments for IBS have targeted serotonin receptors that are involved in motor, sensory and secretory functions of the gut. Serotonergic agents, such as alosetron (a 5-HT3 receptor antagonist) and tegaserod (a selective 5-HT4 receptor partial agonist), provide global relief of the multiple symptoms of IBS with diarrhoea and IBS with constipation, respectively, and represent important additions to the IBS treatment armamentarium.

Central nervous system involvement in functional gastrointestinal disorders

Although functional gastrointestinal disorders (FGID) are common, their pathophysiology remains incompletely understood. It is generally accepted that dysfunction of the bidirectional pathways between the gastrointestinal tract and the central nervous system (the 'brain-gut axis') at any level can cause FGID symptoms. In this review article, we focus on the role of the central nervous system in the brain-gut axis. First, we describe the functional anatomy of the brain-gut axis. Second, we focus on the results from brain-imaging studies both in healthy volunteers and in FGID patients. These new investigational techniques made identification of brain regions critically involved in processing of visceral afferent information possible. Differences in central nervous system response to visceral stimuli between controls and FGID patients will be highlighted. Third, we will address the issue of high comorbidity with psychiatric disorders. Some hypotheses about common pathophysiological substrates will be discussed.

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.