Does a preexisting anxiety disorder predict response to paroxetine in irritable bowel syndrome?

Current and future pharmacological treatments for diarrhea-predominant irritable bowel syndrome

INTRODUCTION

Diarrhea-predominant irritable bowel syndrome (IBS-D) affects about one-third of patients with IBS, which is observed in about 12% of people across five continents. The ultimate goal in this field is to identify the underlying cause of symptoms in order to individualize education of the patient, and to provide optimal treatment of this highly prevalent condition.

AREAS COVERED

This review addresses the pharmacological treatments for IBS-D under three categories: drugs for IBS-D (i.e., the 5-HT3 antagonist, alosetron); drugs approved for other indications that are used in IBS-D (e.g., opioid agonists; other 5-HT3 antagonists; serotonergic psychoactive agents; bile acid binders; 5-ASA compounds; probiotics and non-absorbable antibiotics); as well as development of drugs that are likely to impact the management of IBS-D in the future (e.g., drug absorbents; TPH1 inhibitors; mast cell stabilizers; centrally acting benzodiazepines). The final section addresses key findings: regulatory roadblocks; weaknesses in the current research in this field so far and opportunities to address unmet needs including restoration of normal intestinal barrier function or permeability, and suppression within the intestines of local immune activation that is thought to trigger abnormal motor, sensory and secretory functions in IBS-D.

EXPERT OPINION

While symptomatic treatment of diarrhea is effective, there is a need for new treatments for the IBS-D complex. Greater understanding of the mechanisms in IBS-D has led to promising approaches to develop more efficacious therapies.

Effects on gastrointestinal functions and symptoms of serotonergic psychoactive agents used in functional gastrointestinal diseases

The effects of antidepressants on the gastrointestinal tract may contribute to their potential efficacy in functional dyspepsia and irritable bowel syndrome; buspirone, a prototype 5-HT1A agonist, enhances gastric accommodation and reduces postprandial symptoms in response to a challenge meal. Paroxetine, a selective serotonin reuptake inhibitor, accelerates small bowel but not colonic transit, and this property may not be relevant to improve gut function in functional gastrointestinal disorders. Venlafaxine, a prototype serotonin norepinephrine reuptake inhibitor, enhances gastric accommodation, increases colonic compliance and reduces sensations to distension; however, it is associated with adverse effects that reduce its applicability in treatment of functional gastrointestinal disorders. Tricyclic antidepressants reduce sensations in response to food, including nausea, and delay gastric emptying, especially in females. Buspirone appears efficacious in functional dyspepsia; amitriptyline was not efficacious in a large trial of children with functional gastrointestinal disorders. Clinical trials of antidepressants for treatment of irritable bowel syndrome are generally small. The recommendations of efficacy and number needed to treat from meta-analyses are suspect, and more prospective trials are needed in patients without diagnosed psychiatric diseases. Antidepressants appear to be more effective in the treatment of patients with anxiety or depression, but larger prospective trials assessing both clinical and pharmacodynamic effects on gut sensorimotor function are needed.

Asian consensus on irritable bowel syndrome

BACKGROUND AND AIMS

Many of the ideas on irritable bowel syndrome (IBS) are derived from studies conducted in Western societies. Their relevance to Asian societies has not been critically examined. Our objectives were to bring to attention important data from Asian studies, articulate the experience and views of our Asian experts, and provide a relevant guide on this poorly understood condition for doctors and scientists working in Asia.

METHODS

A multinational group of physicians from Asia with special interest in IBS raised statements on IBS pertaining to symptoms, diagnosis, epidemiology, infection, pathophysiology, motility, management, and diet. A modified Delphi approach was employed to present and grade the quality of evidence, and determine the level of agreement.

RESULTS

We observed that bloating and symptoms associated with meals were prominent complaints among our IBS patients. In the majority of our countries, we did not observe a female predominance. In some Asian populations, the intestinal transit times in healthy and IBS patients appear to be faster than those reported in the West. High consultation rates were observed, particularly in the more affluent countries. There was only weak evidence to support the perception that psychological distress determines health-care seeking. Dietary factors, in particular, chili consumption and the high prevalence of lactose malabsorption, were perceived to be aggravating factors, but the evidence was weak.

CONCLUSIONS

This detailed compilation of studies from different parts of Asia, draws attention to Asian patients' experiences of IBS.

A double-blind, randomized, placebo-controlled trial of paroxetine controlled-release in irritable bowel syndrome

BACKGROUND

Irritable bowel syndrome (IBS) is a functional gastrointestinal (GI) disease that causes significant impairment in quality of life and accounts for $8 billion per year to the healthcare system and loss of productivity in the workplace.

OBJECTIVE

The authors examined the efficacy and safety of paroxetine controlled-release (paroxetine-CR) in patients with IBS.

METHOD

Seventy-two patients with IBS participated in a 12-week, double-blind, randomized, placebo-controlled study of paroxetine-CR (12.5 mg-50 mg/day). Efficacy was measured by Composite Pain Scores (primary outcome) and the Clinical Global Impression-Improvement (CGI-I) and Severity (CGI-S) ratings.

RESULTS

In intent-to-treat analyses, there were no significant differences between paroxetine-CR (N=36) and placebo (N=36) on reduction in Composite Pain Scores, although the proportion of responders on CGI-I was significantly higher in the paroxetine-CR group. The treatment was well tolerated.

CONCLUSION

The study did not demonstrate a statistically significant benefit for paroxetine-CR over placebo on the primary outcome measure, although there was improvement in secondary outcome measures. Overall, paroxetine-CR seems to have potential benefit in IBS. Studies with adequate samples may clarify the role of paroxetine-CR in IBS.

Acute tryptophan depletion alters gastrointestinal and anxiety symptoms in irritable bowel syndrome

OBJECTIVES

To assess the effect of acute changes in serotonin (5-HT) synthesis using the acute tryptophan depletion (ATD) paradigm on gastrointestinal (GI) and mood symptoms in irritable bowel syndrome (IBS).

METHODS

In a randomized double-blind crossover study, 29 subjects (18 patients with ROME II defined IBS and 11 age-matched controls) were studied under ATD and acute tryptophan increase (ATI) conditions. GI symptoms, mood and anxiety ratings, as well as plasma tryptophan concentrations were measured.

RESULTS

Total (and free) plasma tryptophan concentrations decreased on the ATD day in patients (73%[82%]) and controls (73%[80%]), and increased on the ATI day in patients (59%[143%]) and controls (61%[381%]). Compared with the ATD day, IBS patients reported more GI symptoms on the ATI day at +210 (p < 0.001) and at +270 (p < 0.05) min post drink. IBS patients also reported less anxiety on the ATI day compared with the ATD day at +270 min (p < 0.001). ATD and ATI did not affect these ratings in control participants. IBS patients had a lower mood compared with controls (p < 0.05), but this did not differ between the ATI and ATD days in either group.

CONCLUSIONS

IBS patients' GI and anxiety responses to changes in tryptophan load differ from controls. This suggests a difference in serotonergic functioning between these two groups and provides evidence to support the hypothesis that 5-HT dysfunction is involved in IBS.

Management of patients with chronic abdominal pain in clinical practice

A practical approach to the management of chronic abdominal pain is needed, given the high prevalence and impact of this problem. This article describes an approach that has evolved based on clinical experience and review of the literature: identifying predominant bloaters and abdominal wall pain; exclusion of organic disease, including consideration of laparoscopy for diagnosis; consideration of chronic functional abdominal pain and the first and second line pharmacotherapies; and seeking specialist care in a pain clinic, psychiatry, or behavioural therapy.

Pharmacological and pharmacokinetic aspects of functional gastrointestinal disorders

Medications are commonly used for the treatment of patients with functional gastrointestinal disorders. The general goal of this report is to review the pharmacokinetics and pharmacology of medications used in functional gastrointestinal disorders. Methods included literature review, consensus evaluation of the evidence for each topic assigned originally to 1 or 2 authors, and broader review at a harmonization session as part of the Rome III process. This report reviews the animal models that have been validated for the study of effects of pharmacologic agents on sensation and motility; the preclinical pharmacology, pharmacokinetics, and toxicology usually required for introduction of novel therapeutic agents; the biomarkers validated for studies of sensation and motility end points with experimental medications in humans; the pharmacogenomics applied to these medications and disorders; and the pharmacology of agents that are applied or have potential for treatment of functional gastrointestinal disorders, including psychopharmacologic agents. Clinician and basic investigators involved in the treatment or investigation of functional gastrointestinal disorders or disease models need to have a comprehensive understanding of a vast range of medications. It is anticipated that the interaction between investigators of basic science, basic and applied pharmacology, and clinical trials will lead to better treatment of these disorders.

Prevalence of irritable bowel syndrome in obsessive-compulsive disorder

INTRODUCTION

Irritable bowel syndrome (IBS) occurs more frequently in psychiatric patients, especially those with anxiety and mood disorders.

METHODS

We sought to determine the prevalence and phenomenology of IBS in patients diagnosed with obsessive-compulsive disorder (OCD). A semi-structured diagnostic interview was administered to patients seeking treatment for OCD in outpatient settings. Structured questions regarding gastrointestinal functioning and IBS symptoms were administered. IBS was diagnosed by a gastroenterologist using Rome I criteria.

RESULTS

Thirty-seven patients (35.1%) with OCD met criteria for IBS. Of these, 53.8% had IBS with both diarrhea and constipation, 30.8% had diarrhea-predominant IBS, and 15.4% had constipation-predominant IBS. The prevalence rate of IBS in an age- and sex-matched control group (n=40) of medical patients in a family practice was 2.5%. IBS prevalence rates were significantly higher for OCD patients than control subjects (P=.0002).

CONCLUSION

IBS and psychiatric illness have high rates of bi-directional comorbidity. This study shows that 35.1% of patients with OCD satisfied criteria for IBS in contrast to 2.5% of the controlled subjects. In most patients the IBS was characterized by both diarrhea and constipation. While taking the initial history clinicians should inquire about bowel symptoms in patients presenting with psychiatric illnesses, including OCD. SSRIs could potentially worsen such symptoms and lead to non-adherence.

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.

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.

Abdominal bloating

Abdominal bloating is a common and significant clinical problem that remains to be scientifically addressed. Bloating is one of the most bothersome complaints in patients with various functional gut disorders. However, in the current standard classification, abdominal bloating is merely regarded as a secondary descriptor, which masks its real clinical effect. Four factors are involved in the pathophysiology of bloating: a subjective sensation of abdominal bloating, objective abdominal distention, volume of intra-abdominal contents, and muscular activity of the abdominal wall. The primer to elicit subjective bloating may be any of the other 3 factors, or the sensation may be related to distorted perception. All of these mechanisms may play an independent role or may be interrelated. Gas transit studies have evidenced that patients with bloating have impaired reflex control of gut handling of contents. Segmental pooling, either of gas or of solid/liquid components, may induce a bloating sensation, particularly in patients with altered gut perception. Furthermore, altered viscerosomatic reflexes may contribute to abdominal wall protrusion and objective distention, even without major intra-abdominal volume increment. Bloating probably is a heterogeneous condition produced by a combination of pathophysiological mechanisms that differ among individual patients and that in most cases are subtle and undetectable by conventional methods. Further advances in the pathophysiology and clinical forms of bloating are warranted to develop mechanistic strategies rather than the current empiric treatment strategies for comprehensive and effective management of this problem.

The interface of psychiatry and irritable bowel syndrome

The interface of psychiatry and irritable bowel syndrome (IBS) is well established, with psychiatric comorbidity approaching 20% to 60%. Anxiety disorders, depressive disorders, and somatoform disorders are the more frequently occurring comorbid conditions. Moreover, psychosocial stressors and history of trauma and abuse play a significant role in the onset and perpetuation of IBS symptoms. The psychiatric management of IBS more effectively uses a collaborative approach between a mental health practitioner and a primary care clinician or gastroenterologist. Psychiatric treatment includes the use of pharmacotherapy with antidepressants or anxiolytics, psychotherapy, and attention to psychosocial stressors. Psychiatric interventions have consistently demonstrated effectiveness in reducing IBS symptoms and improvement of patient functioning.

What has dry cough in common with pruritus? Treatment of dry cough with paroxetine

Distressing persistent dry cough is commonly the consequence of sensitization of the cough reflex. A slight and transient peripheral nociceptive impulse, such as bronchitis, may be perpetuated for weeks because of sensitization of the cough reflex. Cough usually can be inhibited by opioids, but some types of cough can be out of opioid control or even be induced by opioids. We describe here a series of 5 patients with dry cough that did not respond to codeine. Because two of these patients also suffered with pruritus, paroxetine was tried. In all patients, cough ceased within hours to days. The only observed adverse effect was sleepiness in the first days of therapy. Paroxetine should be investigated as antitussive in cases of opioid-resistant cough. The putative mechanism of action of paroxetine on pruritus and rough is discussed.

Medically unexplained physical symptoms: toward an alternative paradigm for diagnosis and treatment

The treatment of patients with unexplained medical symptoms is difficult because there is neither a clear etiology for the symptoms, nor a useful paradigm with which to understand and treat them. Patients with such symptoms are often referred to psychiatry with vague diagnoses of "somatization" or "hypochondriasis." Rather than considering somatoform diagnoses based on the number or diversity of physical symptoms, evolving research suggests an emphasis on the type of physical symptom as an indicator of Axis I pathology. This article links specific symptomatic complaints, such as chronic pain, chest pain, and dizziness, to the respective Axis I disorders associated with them, such as depression, panic disorder, and anxiety disorders.