Chronic Intestinal Pseudoobstruction

Surgical and Therapeutic Interventions for Chronic Intestinal Pseudo-obstruction: A Scoping Review

Background/Aims

Chronic intestinal pseudo-obstruction (CIPO) is a rare cause of intestinal dysmotility. First-line treatment in adult patients is medical and nutritional therapy. For patients who fail these treatment options, surgical interventions may be an option. In this scoping review, we aim to investigate the current research on surgical interventions for CIPO in adults.

Methods

PubMed, Embase, and Scopus were queried for articles related to surgical interventions for adults with CIPO. Search terms included: intestinal dysmotility, intestinal pseudo-obstruction, global intestinal dysmotility, chronic intestinal pseudo-obstruction, gastrointestinal paresis, neurogastrointestinal motility disorder, and chronic small intestinal motility disorder.

Results

Initial search identified 4763 records; 4722 were deemed irrelevant after screening and were excluded. The remaining 41 reports were retrieved and assessed for eligibility. Twenty-one additional studies were excluded after in-depth assessment. The remaining 20 reports were: 9 cohort studies, 7 case reports, and 4 reviews. Of these, 10 studies had study populations of < 10 patients, while 6 had ≥ 10 patients. The remaining 4 were reviews. Results of these papers described the safety and effectiveness of various surgical interventions for adults with CIPO, including percutaneous endoscopic procedures, surgical decompression, small bowel resection, and intestinal transplantation.

Conclusions

Data pertaining to surgical therapy for CIPO is limited. Although this review suggests that surgical interventions for CIPO may be safe and effective for select patients, strong conclusions cannot be made due to limited number of relevant studies and small sample sizes. Concerted efforts to produce data from large studies on adults with CIPO are necessary.

Pediatric Intestinal Pseudo-Obstruction: An International Survey on Diagnostic and Management Strategies in the European Reference Network for Rare Inherited and Congenital Anomalies Intestinal Failure Teams

OBJECTIVES

Pediatric intestinal pseudo-obstruction (PIPO) management is based on nutritional, medical, and surgical care while available evidence is scarce. The aim of this study was to outline the current diagnostic and management strategies in intestinal failure (IF) teams of the European Reference Network for rare Inherited and Congenital Anomalies (ERNICA) and to compare these practices to the latest PIPO international guidelines.

METHODS

An online survey on institutional diagnostic and management strategies of PIPO was conducted among the ERNICA IF teams.

RESULTS

In total, 11 of 21 ERNICA IF centers from 8 countries participated. On average, 64% of teams had ≥6 and 36% had 1-5 PIPO patients under active follow-up. In total, 80 of 102 PIPO patients were parenteral nutrition (PN) dependent while each IF team had median 4 (range 0-19) PN dependent PIPO patients under follow-up. On average, each center received 1-2 new PIPO patients per year. Diagnostics mostly followed current guidelines while medical and surgical management strategies were diverse.

CONCLUSIONS

Numbers of PIPO patients are low and management strategies are diverse among ERNICA IF teams. To improve PIPO patient care, regional reference centers with specialized multidisciplinary IF teams and continuous collaboration across centers are needed.

TGFβR-1/ALK5 inhibitor RepSox induces enteric glia-to-neuron transition and influences gastrointestinal mobility in adult mice

Promoting adult neurogenesis in the enteric nervous system (ENS) may be a potential therapeutic approach to cure enteric neuropathies. Enteric glial cells (EGCs) are the most abundant glial cells in the ENS. Accumulating evidence suggests that EGCs can be a complementary source to supply new neurons during adult neurogenesis in the ENS. In the brain, astrocytes have been intensively studied for their neuronal conversion properties, and small molecules have been successfully used to induce the astrocyte-to-neuron transition. However, research on glia-to-neuron conversion in the ENS is still lacking. In this study, we used GFAP-Cre:Rosa-tdTomato mice to trace glia-to-neuron transdifferentiation in the ENS in vivo and in vitro. We showed that GFAP promoter-driven tdTomato exclusively labelled EGCs and was a suitable marker to trace EGCs and their progeny cells in the ENS of adult mice. Interestingly, we discovered that RepSox or other ALK5 inhibitors alone induced efficient transdifferentiation of EGCs into neurons in vitro. Knockdown of ALK5 further confirmed that the TGFβR-1/ALK5 signalling pathway played an essential role in the transition of EGCs to neurons. RepSox-induced neurons were Calbindin- and nNOS-positive and displayed typical neuronal electrophysiological properties. Finally, we showed that administration of RepSox (3, 10 mg· kg^-1 ·d^-1, i.g.) for 2 weeks significantly promoted the conversion of EGCs to neurons in the ENS and influenced gastrointestinal motility in adult mice. This study provides a method for efficiently converting adult mouse EGCs into neurons by small-molecule compounds, which might be a promising therapeutic strategy for gastrointestinal neuropathy.

Management of bloating

Abdominal bloating is a subjective sensation of trapped abdominal gas, producing abdominal pressure, fullness sensation, and, in some patients, associated objective abdominal distension. In this month's edition of the journal, a new validated questionnaire to assess the prevalence and impact of gas-related symptoms is presented by Duracinsky et al., showing that gas-related abdominal symptoms are prevalent in patients with irritable bowel syndrome and have a measurable impact on patients daily life. A parallel study by Gardiner et al. assessing the severity of bloating in functional gastrointestinal disorders shows that severe bloating is associated with the severity of abdominal pain, constipation, and somatization, advancing our understanding of the clinical characteristics and relevance of gas-related symptoms in the broad spectrum of functional gastrointestinal disorders. Management of bloating includes non-pharmacological and pharmacological strategies. Dietary interventions to reduce intestinal fermentation and ingestion of food supplements like prebiotics or probiotics can reduce bloating by reducing gas production. The main targets of pharmacological treatments are to improve transit and evacuation with prokinetics, to improve intestinal gas tolerance with antispasmodics and/or neuromodulators, and to modify intestinal microbiota with antibiotics. Secretagogues act by increasing intestinal secretion and decreasing visceral sensitivity and have been reported to be an effective treatment alternative for patients with bloating associated with constipation. Biofeedback therapy addressed to correct abdomino-phrenic dysynergia may be useful for patients with objective abdominal distension, and patients with bloating associated with outlet obstructed defecation may benefit from anorectal biofeedback.

Chronic intestinal pseudo-obstruction: a case report with review of the literature and practical guidance for the clinician

Chronic Intestinal Pseudo-obstruction (CIPO) is a rare but debilitating and severe form of gastrointestinal dysmotility. The diagnosis is often made very late in the disease course due to its rarity and complexity. Treatment is mainly supportive, as there is no definitive cure. Pharmacologic therapy comprises prokinetics, antibiotics for bacterial overgrowth and pain management. Pain can also be alleviated with intestinal decompression in selected cases. Beside the pharmacologic therapy, nutrition and fluid replacement play a key role. Rarely, intestinal transplantation is necessary in patients with CIPO and intestinal failure. In this review, we describe an advanced CIPO case and provide an update of the clinical and diagnostic features and current management strategies. The goal of our review is to raise awareness around CIPO and to give practical guidance for the clinician.

A Novel Approach to the Symptomatic Management of Chronic Megacolon

Background

Chronic megacolon is a rare condition which primarily occurs in patients with autonomic dysfunction of a variety of causes. Its management is often challenging and people with chronic megacolon often suffer from abdominal distension, pain, and malabsorption. Given the struggles clinicians experience in managing these patients long term, this case study provides an example of an alternate strategy for the symptomatic management of chronic megacolon. Case Description. An 80-year-old male with early Parkinson's disease developed megacolon following a basal ganglia stroke. He had a protracted hospital stay over 6 months due to malabsorption requiring total parenteral nutrition and electrolyte disturbances. A trial of subcutaneous neostigmine was unsuccessful, so patient underwent a trial of intermittent rectal tube decompression which improved his symptoms and malabsorption. This technique was then taught to the patient's wife until she was confident performing this herself. With continuation of decompression approximately every three days, the patient was able to return to oral nutrition and no longer required ongoing electrolyte replacement. He was able to be discharged into the community with significant improvement in his quality of life.

Conclusion

This is the first report to suggest the benefit of intermittent rectal tube decompression in the community for the long-term management of chronic megacolon. Further prospective studies should evaluate the potential for this strategy to be implemented in a wider cohort of patients who are not responsive to existing treatments for chronic megacolon.

Latest developments in chronic intestinal pseudo-obstruction

Chronic intestinal pseudo-obstruction (CIPO) is a type of intestinal dysfunction presenting as symptoms of intestinal obstruction but without actual mechanical obstruction. An extremely low incidence, non-specific clinical symptoms, strong heterogeneity, and no definitive cause in some patients make CIPO very difficult to diagnose correctly. Imaging and gastrointestinal manometry are commonly used. Most patients have progressive worsening of their symptoms and require intervention, and nutritional assessment and treatment are very important to determine the prognosis. With improvements in surgical techniques, small bowel transplantation is a feasible treatment option for patients with advanced CIPO; however, the long-term prognosis for CIPO patients remains unsatisfactory. Generally, the disease is rare and difficult to diagnose, which leads to clinicians' lack of understanding of the disease and results in a high rate of misdiagnosis. This review describes the characteristics of CIPO and the latest developments in diagnosis and treatment, in detail. The goal of our review is to improve clinicians' understanding of CIPO so that the disease is identified quickly and accurately, and treated as early as possible to improve patients' quality of life.

Pathophysiology, Diagnosis, and Management of Chronic Intestinal Pseudo-Obstruction

Chronic intestinal pseudo-obstruction (CIPO) is a rare disorder characterized by an impairment of coordinated propulsive activity in the gastrointestinal (GI) tract, which clinically mimics mechanical intestinal obstruction. CIPO is the most severe and debilitating form of GI dysmotility. CIPO may be primary or be secondary to pathology at any level of the brain-gut axis as well as systemic disease. The clinical features of CIPO are pleomorphic and largely depend on the site and extent of the segment of the GI tract involved. The diagnostic approach includes the need for investigations to exclude mechanical GI obstruction, screening for causes of secondary CIPO and the identification of the disease phenotype as well as the prompt recognition and treatment of complications such as malnutrition and small intestinal bacterial overgrowth. In managing this disorder, a holistic, multidisciplinary approach is needed with judicious use of pharmacotherapeutic agents. While currently there are no specific therapeutic modalities for CIPO, treatment is largely directed at maintaining adequate nutrition and electrolyte balance and enhancing coordinated GI motility. Surgery should be avoided unless advisable for carefully selected patients and may include stoma formation. This narrative review provides a concise overview of the literature on this rare, severe and complex disorder, and highlights the need and areas for further research to improve both diagnostics and therapeutics.

Paediatric Intestinal Pseudo-obstruction: Evidence and Consensus-based Recommendations From an ESPGHAN-Led Expert Group

OBJECTIVES

Chronic intestinal pseudo-obstructive (CIPO) conditions are considered the most severe disorders of gut motility. They continue to present significant challenges in clinical care despite considerable recent progress in our understanding of pathophysiology, resulting in unacceptable levels of morbidity and mortality. Major contributors to the disappointing lack of progress in paediatric CIPO include a dearth of clarity and uniformity across all aspects of clinical care from definition and diagnosis to management. In order to assist medical care providers in identifying, evaluating, and managing children with CIPO, experts in this condition within the European Society for Pediatric Gastroenterology, Hepatology, and Nutrition as well as selected external experts, were charged with the task of developing a uniform document of evidence- and consensus-based recommendations.

METHODS

Ten clinically relevant questions addressing terminology, diagnostic, therapeutic, and prognostic topics were formulated. A systematic literature search was performed from inception to June 2017 using a number of established electronic databases as well as repositories. The approach of the Grading of Recommendations Assessment, Development and Evaluation (GRADE) was applied to evaluate outcome measures for the research questions. Levels of evidence and quality of evidence were assessed using the classification system of the Oxford Centre for Evidence-Based Medicine (diagnosis) and the GRADE system (treatment). Each of the recommendations were discussed, finalized, and voted upon using the nominal voting technique to obtain consensus.

RESULTS

This evidence- and consensus-based position paper provides recommendations specifically for chronic intestinal pseudo-obstruction in infants and children. It proposes these be termed paediatric intestinal pseudo-obstructive (PIPO) disorders to distinguish them from adult onset CIPO. The manuscript provides guidance on the diagnosis, evaluation, and treatment of children with PIPO in an effort to standardise the quality of clinical care and improve short- and long-term outcomes. Key recommendations include the development of specific diagnostic criteria for PIPO, red flags to alert clinicians to the diagnosis and guidance on the use of available investigative modalities. The group advocates early collaboration with expert centres where structured diagnosis and management is guided by a multi-disciplinary team, and include targeted nutritional, medical, and surgical interventions as well as transition to adult services.

CONCLUSIONS

This document is intended to be used in daily practice from the time of first presentation and definitive diagnosis PIPO through to the complex management and treatment interventions such as intestinal transplantation. Significant challenges remain to be addressed through collaborative clinical and research interactions.

Octreotide-Associated Neutropenia

Drug-induced neutropenia and agranulocytosis are rare adverse events but can be fatal. Neutropenia can be induced by a myriad of drugs from almost every pharmacologic class. Octreotide is a somatostatin analog that has been used to treat variceal bleeding, acromegaly, and severe diarrhea associated with metastatic tumors, and to reduce symptoms in the setting of malignant bowel obstruction and pseudoobstruction. The most common adverse effects associated with octreotide include pain at the injection site and gastrointestinal effects such as loose stools, cramping, and nausea; neutropenia is not currently listed as an adverse effect of the drug. We describe the case of an 87-year-old man who developed neutropenia immediately after administration of three doses of subcutaneous octreotide. He presented to the hospital with a history of constipation and straining for 3 days. He was admitted, and laxatives, suppositories, and enemas were administered over the next 3 days to induce a bowel movement; however, they were ineffective. Bowel obstruction secondary to a mass was confirmed by computed tomography; the mass was eventually diagnosed as colon cancer. Octreotide 100 µg subcutaneously every 8 hours was started for the obstruction on the evening of hospital day 4. After the patient had received 3 doses of octreotide, his white blood cell count (WBC) had decreased from 4.1 × 10³ /mm³ (neutrophils 75.4%, absolute neutrophil count [ANC] 3.1 × 10³ /mm³ ) on admission to 1.6 × 10³ /mm³ (neutrophils 62%, ANC 0.99 × 10³ /mm³ ) on day 5. Given the temporal relationship of octreotide and neutropenia as well as the lack of a reasonable alternative cause, it was suspected that octreotide was the most likely culprit of the patient's neutropenia. Octreotide was subsequently discontinued, and his WBC increased to 4.9 × 10³ /mm³ (neutrophils 66.3%, ANC 3.2 × 10³ /mm³ ) the next day. The remainder of the patient's hospitalization was not significant for any further hematologic abnormalities. His WBC and ANC (WBC 6.7 × 10³ /mm³ , neutrophils 83.2%, ANC 5.6 × 10³ /mm³ ) remained stable 30 days after the incident. Use of the Naranjo Adverse Drug Reaction Probability Scale indicated a probable relationship (score of 5) between the patient's development of neutropenia and octreotide therapy. To our knowledge, this report highlights the first case of octreotide-associated neutropenia. Although the frequency of drug-induced neutropenia remains rare outside of cytotoxic chemotherapy, the importance of recognizing this adverse effect cannot be understated given the mortality risks for neutropenic patients.

Management of gastrointestinal complications in hereditary transthyretin amyloidosis: a single-center experience over 40 years

Hereditary transthyretin amyloidosis (ATTRm amyloidosis) is a rare disease caused by the deposition and accumulation of insoluble non-native transthyretin fibrils in the body. The disease inevitably results in widespread organ disruption, and poor life expectancy. The GI tract is one organ system vulnerable to disruption and, although the clinical presentation of the disease varies, GI involvement affects most patients with ATTRm amyloidosis. Areas covered: This article presents our experience with diagnosing and treating the GI symptoms of ATTRm amyloidosis patients at our center over the last 40 years, in the Swedish clustering area of the disease. Our aim is to help other physicians to better manage GI complications in patients with this rare but widespread condition. Expert commentary: GI symptoms are debilitating complications for ATTRm amyloidosis patients to experience, yet with the appropriate questioning and diagnosis methods, symptomatic treatments of these symptoms can be implemented to provide relief. Further, patients with fewer GI complications and a good nutritional status are also better candidates for liver transplantation which, in selected cases, is the best disease-modifying treatment of ATTRm amyloidosis to date.

Small Intestinal Bacterial Overgrowth and Other Intestinal Disorders

Gut microbiota is the largest organ of the human body. Although growth of bacteria more than 10⁵ colony forming unit (CFU) per milliliter in culture of upper gut aspirate is used to diagnosis small intestinal bacterial overgrowth (SIBO), 10³ CFU or more is being considered to suggest the diagnosis, particularly if colonic type bacteria are present in the upper gut. Although neither very sensitive nor specific, hydrogen breath tests are widely used to diagnose SIBO. Rifaximin is the best treatment for SIBO due to its broad spectrum, lack of systemic absorption, and safety profile.

Chronic intestinal pseudo-obstruction in children and adults: diagnosis and therapeutic options

BACKGROUND

Chronic intestinal pseudo-obstruction (CIPO) represents the most severe form of gastrointestinal dysmotility with debilitating and potentially lethal consequences. Symptoms can be non-specific, and result in this condition being diagnosed incorrectly or too late with consequences for morbidity and even mortality.

PURPOSE

The present article aims to provide pediatric and adult gastroenterologists with an up to date review about clinical features, diagnosis and therapeutic options for CIPO. Although pediatric and adult CIPO share many clinical aspects distinctive features can be identified. There is no single diagnostic test or pathognomonic finding of CIPO, thus a stepwise approach including radiology, endoscopy, laboratory, manometry, and histopathology should be considered in the diagnostic work-up. Treatment of patients with CIPO is challenging and requires a multidisciplinary effort with participation of appropriately experienced gastroenterologists, pathologists, dieticians, surgeons, psychologists, and other subspecialists based on the presence of comorbidities. Current treatment options invariably involve surgery and specialized nutritional support, especially in children. Medical therapies are mainly aimed to avoid complications such as sepsis or intestinal bacterial overgrowth and, where possible, restore intestinal propulsion. More efficacious therapeutic options are eagerly awaited for such difficult patients.

Building a second brain in the bowel

The enteric nervous system (ENS) is sometimes called the "second brain" because of the diversity of neuronal cell types and complex, integrated circuits that permit the ENS to autonomously regulate many processes in the bowel. Mechanisms supporting ENS development are intricate, with numerous proteins, small molecules, and nutrients that affect ENS morphogenesis and mature function. Damage to the ENS or developmental defects cause vomiting, abdominal pain, constipation, growth failure, and early death. Here, we review molecular mechanisms and cellular processes that govern ENS development, identify areas in which more investigation is needed, and discuss the clinical implications of new basic research.

Repetitive Colonoscopic Decompression as a Bridge Therapy before Surgery in a Pregnant Patient with Chronic Intestinal Pseudo-Obstruction

Chronic intestinal pseudo-obstruction is a rare clinical syndrome which is characterized by intestinal obstruction without occluding lesions in the intestinal lumen and pregnancy is one of the important aggravating factors. Here, we report a case of a woman with intractable intestinal pseudo-obstruction that was precipitated by pregnancy. She could not make any stool passage for more than 4 weeks until a fetal gestational age of 17 weeks was reached. However, the patient could be maintained by repetitive colonoscopic decompressions and finally total colectomy could be performed successfully at a fetal gestational age of 21 weeks.

Chronic intestinal pseudo-obstruction: clinical features, diagnosis, and therapy

CIPO is the very “tip of the iceberg” of functional gastrointestinal disorders, being a rare and frequently misdiagnosed condition characterized by an overall poor outcome. Diagnosis should be based on clinical features, natural history and radiologic findings. There is no cure for CIPO and management strategies include a wide array of nutritional, pharmacologic, and surgical options which are directed to minimize malnutrition, promote gut motility and reduce complications of stasis (ie, bacterial overgrowth). Pain may become so severe to necessitate major analgesic drugs. Underlying causes of secondary CIPO should be thoroughly investigated and, if detected, treated accordingly. Surgery should be indicated only in a highly selected, well characterized subset of patients, while isolated intestinal or multivisceral transplantation is a rescue therapy only in those patients with intestinal failure unsuitable for or unable to continue with TPN/HPN. Future perspectives in CIPO will be directed toward an accurate genomic/proteomic phenotying of these rare, challenging patients. Unveiling causative mechanisms of neuro-ICC-muscular abnormalities will pave the way for targeted therapeutic options for patients with CIPO.

Vincristine and intestinal pseudo-obstruction in children: report of 5 cases, literature review, and suggested management

Intestinal pseudo-obstruction is a rare complication resulting from a variety of disorders. Symptoms include abdominal pain, nausea, vomiting, diarrhea, constipation, and malnutrition. Vincristine-related pseudo-obstruction has been reported in the literature, but its description in children and recommendations for management are lacking. A review of the literature revealed 21 reported pediatric cases of vincristine-related pseudo-obstruction. Most have, however, been attributed to a drug interaction with itraconazole, accidental vincristine overdose, or liver failure. Potential genetic causes are rarely addressed. We present here 5 cases of pseudo-obstruction related to vincristine without any identifiable predisposing factors, and a suggested algorithm for management.

Three-generation familial visceral myopathy with alpha-actin-positive inclusion bodies in intestinal smooth muscle

We report the clinical and histopathologic findings of a family with 7 affected members in 3 generations suffering from autosomal dominant visceral myopathy. All patients presented with chronic intestinal pseudo-obstruction affecting especially the entire small bowel. Histologic abnormalities involved intestinal smooth muscle, with degeneration and fibrosis of the muscularis propria. In addition, the inner circular layer of the muscularis propria contained alpha-smooth muscle actin-positive and, in more advanced disease, also periodic acid-Schiff-positive inclusion bodies. The inclusions were invisible in routine hematoxylin-eosin-stained sections, but were visible in immunohistochemical stainings for alpha-smooth muscle actin. No abnormality was evident in muscularis mucosae or in blood vessels, and the findings remained unidentified in mucosal biopsy specimens. To our knowledge, this is the first reported alpha-actin-positive inclusion body finding in familial visceral myopathy.

Chronic intestinal pseudo-obstruction

Chronic intestinal pseudo-obstruction (CIPO) is a severe digestive syndrome characterized by derangement of gut propulsive motility which resembles mechanical obstruction, in the absence of any obstructive process. Although uncommon in clinical practice, this syndrome represents one of the main causes of intestinal failure and is characterized by high morbidity and mortality. It may be idiopathic or secondary to a variety of diseases. Most cases are sporadic, even though familial forms with either dominant or recessive autosomal inheritance have been described. Based on histological features intestinal pseudo-obstruction can be classified into three main categories: neuropathies, mesenchymopathies, and myopathies, according on the predominant involvement of enteric neurones, interstitial cells of Cajal or smooth muscle cells, respectively. Treatment of intestinal pseudo-obstruction involves nutritional, pharmacological and surgical therapies, but it is often unsatisfactory and the long-term outcome is generally poor in the majority of cases.

Chronic intestinal pseudo-obstruction

Chronic intestinal pseudo-obstruction (CIPO) is a severe functional digestive syndrome characterised by a derangement of gut propulsive motility which resembles mechanical obstruction. It may be associated with disabling and potentially life-threatening complications. CIPO can be secondary to a variety of diseases, but it is more frequently idiopathic. Most cases are sporadic, but familial forms have also been described. Based on histological features CIPO can be classified into three major entities: neuropathies, mesenchymopathies, and myopathies depending on the predominant involvement of enteric neurones, interstitial cells of Cajal (ICC) or smooth muscle cells, respectively. Mitochondriopathies may be responsible for a syndromic form of CIPO, i.e. mitochondrial neurogastrointestinal encephalomyopathy. Management of CIPO involves nutritional, pharmacological and surgical therapies, but the long-term outcome turns out to be poor in the vast majority of cases. The main pathogenetic and clinical features of the syndrome, together with current management recommendations are reviewed in this chapter.

Serotonin and its role in colonic function and in gastrointestinal disorders

Serotonin (5-HT) is most commonly thought of as a neurotransmitter in the central nervous system. However, the predominant site of serotonin synthesis, storage, and release is the enterochromaffin cells of the intestinal mucosa. Within the intestinal mucosa, serotonin released from EC cells activates neural reflexes associated with intestinal secretion, motility, and sensation. Two important receptors for serotonin that are located in the neural circuitry of the intestines are the 5-HT(3) and 5-HT(4) receptors; these are the targets of drugs designed to treat gastrointestinal disorders. 5-HT(3) receptor antagonists are used to treat nausea and emesis associated with chemotherapy and for functional disorders associated with diarrhea. 5-HT(4) receptor agonists are used as promotility agents to promote gastric emptying and to alleviate constipation. Because of the importance of serotonin in normal gut function and sensation, a number of studies have investigated potential changes in mucosal serotonin signaling in pathologic conditions. Despite the inconsistencies in the current literature, changes in serotonin signaling have now been demonstrated in inflammatory bowel disease, irritable bowel syndrome, postinfectious irritable bowel syndrome, and idiopathic constipation. Emerging evidence has led to many contradictory theories regarding serotonin signaling and its roles in the pathology of gut disorders. This review summarizes the current medications affecting serotonin signaling and provides an overview of our current knowledge of the changes in serotonin that occur in pathologic conditions.

Basic and clinical pharmacology of new motility promoting agents

Recent research has provided new information about drugs that could be used to treat functional motility disorders. Promotility drugs accelerate gastric emptying or colonic transit and these properties may contribute to their efficacy in treating symptoms associated with gastroparesis, functional dyspepsia or constipation. 5-Hydroxytryptamine4 receptors are targets for drugs (tegaserod, renzapride) that treat symptoms in constipated irritable bowel syndrome patients and in gastroparesis. Drugs acting at motilin (erythromycin) and cholecystokinin-1 (dexloxiglumide) receptors accelerate gastric emptying. Dexloxiglumide might be useful in the treatment of functional dyspepsia particularly that associated with lipid intake. Alvimopan is a mu-opioid receptor antagonist that does not cross the blood brain barrier. Alvimopan is effective in treating postsurgical ileus and perhaps opiate-induced bowel dysfunction. Successes and failures of recent efforts to develop promotility agents revealed opportunities and challenges for developing new promotility drugs. The pharmacological properties of partial agonists might be exploited to develop effective promotility drugs. However, opposing actions of promotility agents on motility (increased contraction vs decreased accommodation) limit the clinical efficacy of drugs with these opposing actions. Selection of appropriate patient populations for evaluation of new drugs is also critical.