Functional Dyspepsia: Impaired Fundic Accommodation

Gastric volumetry for the assessment of fundic compliance and visceral hypersensitivity in patients with gastroparesis: a retrospective comparative study

BACKGROUND/AIMS

The evaluation of visceral hypersensitivity and gastric accommodation in patients with gastroparesis (GP) is difficult. CT-scan gastric volumetry allows to test the distension of different regions of the stomach. We aimed to study gastric volumes and patient's sensitivity to gastric distension between in patients with GP compared to patients with GERD.

METHOD

Retrospective study including patients who had CT-scan volumetry for GP or GERD. Two CT-scan series were made after gastric distension: left lateral decubitus 30° (LLD30) for antrum and right lateral decubitus (RLD) for body. Pain and discomfort were assessed using visual analogue scale (VAS). Gastric volumes were measured for LLD30 and RLD.

RESULTS

13 patients (7 GP and 6 GERD) were included. Mean age was 35.6+/-7.3 years. Median gastric volume in the RLD was lower in GP vs GERD (927+/-208 ml vs. 1115+/-163 ml; p = 0.046) while it was similar for LLD30 (1053+/-228 ml vs. 1054+/-193 ml; p = 0.603). GP patients had significantly more pain and discomfort during the procedure: pain VAS for GP was 6[0-9] versus 0[0-2] for GERD, p = 0.004, discomfort VAS for GP was 7[4-10] versus 4[0-5] for GERD, p = 0.007. 66.7% of GERD patients felt no pain vs. 14.3% in GP, p = 0.053.

CONCLUSION

This pilot study suggests that GP could be associated with a reduced gastric volume compared to GERD in RLD after gaseous distension. In contrast, patient self-assessment of pain related to gastric distension was greater int GP patients. A lack of fundus accommodation and visceral hypersensitivity could explain some mechanisms in the genesis of GP symptoms.

Systemic sclerosis gastrointestinal dysmotility: risk factors, pathophysiology, diagnosis and management

Nearly all patients with systemic sclerosis (SSc) are negatively affected by dysfunction in the gastrointestinal tract, and the severity of gastrointestinal disease in SSc correlates with high mortality. The clinical complications of this dysfunction are heterogeneous and include gastro-oesophageal reflux disease, gastroparesis, small intestinal bacterial overgrowth, intestinal pseudo-obstruction, malabsorption and the requirement for total parenteral nutrition. The abnormal gastrointestinal physiology that promotes the clinical manifestations of SSc gastrointestinal disease throughout the gastrointestinal tract are diverse and present a range of therapeutic targets. Furthermore, the armamentarium of medications and non-pharmacological interventions that can benefit affected patients has substantially expanded in the past 10 years, and research is increasingly focused in this area. Here, we review the details of the gastrointestinal complications in SSc, tie physiological abnormalities to clinical manifestations, detail the roles of standard and novel therapies and lay a foundation for future investigative work.

Gastric accommodation: Physiology, diagnostic modalities, clinical relevance, and therapies

BACKGROUND

Gastric accommodation is an essential gastric motor function which occurs following ingestion of a meal. Impaired gastric fundic accommodation (IFA) is associated with dyspeptic symptoms. Gastric accommodation is mediated by the vagal pathway with several important physiologic factors such as duodenal nutrient feedback playing a significant role. IFA has been described as a pathophysiologic factor in several gastrointestinal disorders including functional dyspepsia, diabetic gastropathy, post-Nissen fundoplication, postsurgical gastrectomy, and rumination syndrome. Modalities for gastric accommodation assessment include gastric barostat, intragastric meal distribution via scintigraphy, drinking tests (eg, water load), SPECT, MRI, 2D and 3D ultrasound, and intragastric high-resolution manometry. Several treatment options including sumatriptan, buspirone, tandospirone, ondansetron, and acotiamide may improve symptoms by increasing post-meal gastric volume.

PURPOSE

Our aim is to provide an overview of the physiology, diagnostic modalities, and therapies for IFA. A literature search was conducted on PubMed, Google Scholar, and other sources to identify relevant studies available until December 2020. Gastric accommodation is an important gastric motor function which if impaired, is associated with several upper gastrointestinal disorders. There are an increasing number of gastric accommodation testing modalities; however, each has facets which warrant consideration. Evidence regarding potentially effective therapies for IFA is growing.

Gastroprotective and gastric motility benefits of AD-lico/Healthy Gut™ Glycyrrhiza inflata extract

The aim of this study was to evaluate in vivo both the anti-Helicobacter and the gastric-relaxing effects of AD-lico/Healthy Gut™ in rat models. AD-lico/Healthy Gut™ is a specially prepared commercial formulation of Glycyrrhiza inflata extract that is under clinical development for indications of gastrointestinal disease and inflammatory bowel disease. In the current study, the oral administration of AD-lico/Healthy Gut™ significantly reduced mucosal damage from Helicobacter pylori in rats and decreased the expression of the inflammatory markers iNOS and COX-2 in the test cells. AD-lico/Healthy Gut™ also reduced mucosal damage caused by water immersion stress in rats. The accelerated gastric emptying in normal rats was also seen with AD-lico/Healthy Gut™, providing relief in gastric relaxation in the test animals. The special formulation of AD-lico/Healthy Gut™ with reduced levels of component glycyrrhizin also has benefits in minimizing the potential side effects attributed to glycyrrhizin seen with similar Glycyrrhiza extracts in terms of induction of hypokalemia and muscle weakness. The preparation has a relatively high phenolic compound content relative to other methods of preparation and is indicative of lower glycyrrhizin levels. These results suggest that AD-lico/Healthy Gut™ may provide the necessary relief from a number of stomach discomfort issues faced by a large population of people.

The gastric accommodation response to meal intake determines the occurrence of transient lower esophageal sphincter relaxations and reflux events in patients with gastro-esophageal reflux disease

BACKGROUND

Gastro-esophageal reflux (GER), the retrograde flow of gastric contents into the esophagus is a physiologic phenomenon, which can evoke symptoms and/or lesions in the esophagus (=gastro-esophageal reflux disease or GERD). Proton pump inhibitors (PPIs) reduce gastric acidity; however, as they are unable to control transient lower esophageal sphincter relaxations (TLESRs), the main mechanism for reflux in GERD, they do not abolish reflux. TLESRs occur predominantly in the postprandial period, and they are believed to be triggered by gastric distention. Gastric accommodation (GA) is the physiologic response to gastric distention and serves to prevent a rise in gastric wall tension during food intake. We aimed to study the relationship between GA and TLESRs, as they both are triggered by gastric distention.

METHODS

We studied 12 GERD patients (average age 37 years [range 18-62], 7m/5f) and nine healthy volunteers (average age 27 years [range 22-36], 2m/7f) using high resolution manometry-impedance measurement before and after a mixed meal challenge. We determined the number of TLESRs (with or without reflux) and measured pre- and postprandial IGP. The change in IGP between the pre- and postprandial period (ΔIGP) is used as surrogate for GA. We also measured LES pressure before and after the meal and calculated the change (ΔLESp).

KEY RESULTS

There were no statistical differences between pre- and postprandial IGP in GERD and healthy volunteers and similarly, there was no significant difference between pre- and postprandial LES pressures in GERD patients and healthy volunteers. The number of TLESRs (with or without reflux) was similar in GERD and healthy volunteers. More importantly, we did observe a negative correlation between ΔIGP and the number of TLESRs, irrespective of whether they were associated with reflux or not, in the GERD patients (without reflux r = -0.67, p = 0.017; with reflux r = -0.81, p = 0.0014). The same observations were found in healthy volunteers, where ΔIGP and the number of TLESRs are significantly inversely correlated (without reflux r = -0.87, p = 0.0045; with reflux r = -0.75, p = 0.021). We could not establish a correlation between ΔLESp and the number of TLESRs, neither in GERD patients nor in healthy volunteers.

CONCLUSIONS & INFERENCES

This is the first study showing a clear negative correlation between ΔIGP and the number of TLESRs, irrespective of whether they were associated with reflux or not, both in GERD patients and in healthy subjects. These results suggest that TLESRs and GA are closely linked, probably through activation of mechanoreceptors involved in triggering of TLESRs.

Why dyspepsia can occur without organic disease: pathogenesis and management of functional dyspepsia

Functional dyspepsia (FD), one of the most common conditions in medicine, is a gastrointestinal disorder in which the patient suffers from chronic dyspeptic symptoms such as epigastralgia and a heavy feeling in the stomach despite the absence of organic disease. Elucidating the pathogenesis of FD means answering the question, "Why do symptoms occur?" The factors contributing to symptom manifestation in FD probably should be divided into 3 categories: (1) physiological abnormalities that directly induce symptoms, (2) factors that modify those physiological abnormalities, and (3) factors that govern abnormal responses to stress. The symptoms of FD are directly caused by two major physiological abnormalities-abnormal gastric motility and visceral hypersensitivity-occurring in patients who have acquired excessive responsiveness to stress as a result of the environment during early life, genetic abnormalities, residual inflammation after gastrointestinal infections, or other causes, with the process modified by factors including psychophysiological abnormalities, abnormal secretion of gastric acid, Helicobacter pylori infection, diet, and lifestyle. If the basis of this model of FD pathogenesis is excessive responsiveness of gastrointestinal function to stress and external stimuli, psychosomatic approaches to alter stress perception could be important treatment options. However, in the primary care setting, the treatment of FD has focused on local gastric factors, including abnormal gastric acid secretion, abnormal gastric motility, and H. pylori infection. Acid secretion inhibitors and prokinetics have been commonly used, and H. pylori eradication therapy has been carried out, but the effectiveness of drug therapy has been limited.

Intragastric pressure during food intake: a physiological and minimally invasive method to assess gastric accommodation

BACKGROUND

The stomach relaxes upon food intake and thereby provides a reservoir while keeping the intragastric pressure (IGP) low. We set out to determine whether we could use IGP as a measurement for stomach accommodation during food intake.

METHODS

In fasted healthy volunteers (n = 7-17) a manometer and an infusion catheter were positioned in the proximal stomach. After a stabilization period a nutrient drink was intragastrically infused at 15, 30 and 60 mL min(-1). To investigate the effect of impaired accommodation the effect of N(G)-monomethyl-L-arginine (L-NMMA) was examined. The volunteers scored satiation until maximum, when the experiment ended. The IGP was presented as a change from baseline (mean ± SEM) and compared with repeated measures anova.

KEY RESULTS

Independent on the ingestion speed, the IGP decreased initially and gradually increased thereafter. Volunteers scored maximal satiation after 699 ± 62, 809 ± 90 and 997 ± 120 mL nutrient drink infused (15, 30 and 60 mL min(-1) respectively; P < 0.01). Maximum IGP decrease was 3.4 ± 0.5 mmHg after 205 ± 28 mL, 5.1 ± 0.7 mmHg after 212 ± 46 mL, and 5.2 ± 0.7 mmHg after 296 ± 28 mL infused volume [15, 30 and 60 mL min(-1) respectively; not significant (ns)]. Post hoc analysis showed significant correlations between IGP and satiation score increase. During L-NMMA infusion IGP was significantly increased while subjects drank significantly less (816 ± 91 vs 1032 ± 71 mL; P < 0.005). Interestingly, the correlation between IGP increase and satiation score increase did not differ after L-NMMA treatment.

CONCLUSIONS & INFERENCES

The IGP during nutrient drink ingestion provides a minimally invasive alternative to the barostat for the assessment of gastric accommodation. These findings furthermore indicate that IGP is a major determinant of satiation.

Current understanding of pathogenesis of functional dyspepsia

Functional dyspepsia (FD) is a disorder in which upper abdominal symptoms occur in the absence of organic disease that explains them. Many pathogenic factors have been proposed for FD, including motility abnormalities, visceral hypersensitivity, psychosocial factors, excessive gastric acid secretion, Helicobacter pylori, genetics, environment, diet, lifestyle, and post-infectious FD. Many of those pathogenic factors are also common to irritable bowel syndrome and other functional gastrointestinal disorders, so understanding FD offers a glimpse into the nature of functional gastrointestinal disorders in general. Motility abnormalities and visceral hypersensitivity are thought to be important in the manifestation of FD symptoms, but the other factors are also thought to contribute by interacting and modifying motility and visceral hypersensitivity.

Diagnosis and treatment of dyspeptic patients in Japan

BACKGROUND AND AIM

Although functional gastrointestinal (GI) disorders has been paid more attention recently in Japan, similar to Western countries, the clinical characteristics of dyspeptic patients, current diagnostic approach to dyspeptic patients and current standard treatments for dyspeptic patients are not well known in Japan. This review, in the most part, summarizes two topics about Japanese dyspeptic patients. The first topic is the pros and cons of the diagnosis of Japanese dyspeptic patients using Rome III classification on the basis of our data and the second topic deals with standard treatments for dyspeptic patients-especially by primary care doctors in Japan.

METHODS

We conducted a PubMed search using the following key words alone or in combination: functional dyspepsia (FD), medical treatment, Rome III classification and Japanese.

RESULTS

The Rome III classification for FD does not adequately identify a large proportion of Japanese dyspeptic patients, primarily due to their earlier presentation for medical evaluation. There are many kinds of options for the treatment of FD in Japan: proton-pump inhibitors, histamine H(2) receptor antagonists, mucoprotective agents, Japanese traditional herbal medicines, Helicobacter pylori eradication therapy and prokinetics. Under the current situation, Japanese primary care doctors choose drugs according to each subtype of FD, which means that they prescribe medicine according to the pathogenesis of each patient.

CONCLUSIONS

While the Rome III classification seems logical, some aspects need further evaluation for Japanese dyspeptic patients. Japanese primary care doctors choose drugs appropriately based on the pathogenesis of FD. However, efforts to further elucidate underlying pathophysiologic mechanisms and identify the appropriate patient population using modified Rome classification will be required.

Effects of corydaline from Corydalis tuber on gastric motor function in an animal model

The aim of this study was to evaluate the prokinetic and gastric-relaxing effects of the isoquinoline alkaloid corydaline, which was extracted from Corydalis tubers (CT). Corydaline is a marker compound used for quality control of DA-9701, a prokinetic agent formulated from extracts of Pharbitidis semen and Corydalis tuber that is currently in clinical trials in Korea for the treatment of functional dyspepsia (FD). DA-9701 was previously reported to be a potential therapeutic agent for the treatment of abnormalities in gastrointestinal motor function in FD patients; however, the therapeutic effects of corydaline on FD have yet to be demonstrated in an in vivo study. In the current study, oral administration of corydaline not only significantly accelerated gastric emptying in normal rats but also improved delayed gastric emptying to near normal levels. Furthermore, corydaline induced significant gastric relaxation, shifting the pressure-volume curve towards higher volumes compared to controls. These results suggest that corydaline promotes gastric emptying and small intestinal transit and facilitates gastric accommodation.

Clinical management of motility disorders in children

We review the current clinical evaluation and management of the most common esophageal and gastrointestinal motility disorders in children based on the literature and our experience in a pediatric motility center in the United States. The disorders discussed include esophageal achalasia, pre- and post-fundoplication motility disorders, gastroparesis, motility disorders occurring after repair of congenital atresias, motility disorders associated with gastroschisis, chronic intestinal pseudo-obstruction, motility after intestinal transplantation, motility disorders after colonic resection for Hirschsprung's disease, chronic functional constipation, and motility disorders associated with imperforate anus.

Clinical effects of STW 5 (Iberogast) are not based on acceleration of gastric emptying in patients with functional dyspepsia and gastroparesis

STW 5, a herbal extract, is effective for the treatment of symptoms in patients with functional dyspepsia (FD). However, its mode of action is still unclear and a modulation of gastric motility is hypothesized. This multicentre, placebo-controlled double-blind study addressed the question of whether STW 5 accelerates gastric emptying in patients with FD and gastroparesis. One-hundred and three patients diagnosed with FD were randomly assigned to a treatment with either STW 5 or a liquid placebo for 28 days. The primary end point of the study was a change of a validated gastrointestinal symptom (GIS) score under treatment. Additionally, patients underwent a (13)C octanoic acid breath test for the assessment of the gastric half-emptying time (t(1/2)). Patients with prolonged t(1/2) were diagnosed with gastroparesis and requested to repeat the test at the end of treatment. A change of t(1/2) was defined a secondary study end point. t(1/2) was prolonged in 48.6% of patients in the STW 5 group and in 43.8% of the placebo group. During treatment, t(1/2) increased non-significantly in patients treated with STW 5 (+23 +/- 109 min; P = 0.51) and slightly accelerated among patients in the placebo arm (-26 +/- 51 min; P = 0.77) (P = 0.49). The improvement of the GIS (P = 0.08) and the proportion of patients with a treatment response (P = 0.03) were more pronounced in the STW 5 group. Our findings suggest that the clinical effects of STW 5 in patients with FD and gastroparesis are not directly mediated by an acceleration of gastric emptying. A clear-cut correlation with symptom improvement is still lacking.

Gastroprokinetic effects of DA-9701, a new prokinetic agent formulated with Pharbitis Semen and Corydalis Tuber

To develop a therapeutic for functional dyspepsia (FD), a prokinetic agent, DA-9701 has been newly formulated with Pharbitis Semen and Corydalis Tuber and we evaluated the gastroprokinetic effects of DA-9701 in comparison with conventional prokinetics. Oral administration with DA-9701 not only significantly accelerated gastric emptying in normal rats but also restored the delayed gastric emptying caused by apomorphine and cisplatin up to almost normal levels. For gastrointestinal transit, DA-9701 caused FITC-dextran to travel a significantly longer distance than the control, and in the delayed GI transit models induced by laparotomy and atopine, DA-9701 considerably increased the values of mean geometric center (MGC), while the conventional prokinetics rarely showed significant effects. Furthermore, DA-9701 drastically increased the gastric accommodation in Beagle dogs, shifting the pressure-volume curve toward considerably higher volume compared to the control, which was comparable to that of cisapride. These results indicate that DA-9701 has potential as a safe and effective therapeutic for FD patients with abnormalities in GI motor function.

Application of Rome III criteria in typing and differential diagnosis of abdominal pain of functional gastrointestinal disorders

AIM: To study the application of Rome Ⅲcriteria in typing and differential diagnosis of abdominal pain of functional gastrointestinal disorders(FGID).

METHODS: Abdominal pain in 85 cases of functional abdominal pain syndrome (FAPS), 128 cases of irritable bowel syndrome (IBS), and 50 cases of functional dyspepsia (FD) were typed and differentially diagnosed based on Rome Ⅲ criteria according to the general condition as well as symptoms and signs of patients, and predisposing factors of abdominal pain.

RESULTS: Abdominal pain in FAPS, mainly localized at the abdominal median line and characterized by a shorter period of attack, serious symptoms and young age due to certain social and psychological impact factors, was not found to be related with eating and defecation. The incidence of IBS manifested mainly as abdominal pain and FD was 43.75% and 76.00%, respectively. Gastrointestinal motility disorders in IBS and FD were closely related with eating and defecation. All the patients had similar background of psychological and mental behavioral disorder manifested as disturbance of perception in reduced gastrointestinal pain threshold value.

CONCLUSION: Typing and differential diagnosis of abdominal pain can be made according to its location, specific gastrointestinal motility disturbance related to eating and defecation, attack cycle, and extent of pain in FGID, IBS and FD.

A double-blind, randomized, placebo-controlled trial of itopride (100 and 200 mg three times daily) on gastric motor and sensory function in healthy volunteers

Itopride, a dopamine D2 antagonist and acetylcholinesterase inhibitor, significantly improved symptoms in patients with functional dyspepsia in one phase II randomized trial. However, the mechanisms by which itopride may improve symptoms are unknown. We aimed to compare the effects of two doses of itopride and placebo on gastric volumes, gastric emptying, small bowel transit and satiation in female and male healthy volunteers. Randomized, double-blind, placebo-controlled study evaluated gastric function before and after 7 days of itopride 100 mg (n = 16) or 200 mg (n = 15) or placebo (n = 15) t.i.d. Validated methods were used to study gastric accommodation (single photon emission computed tomography), gastric emptying and orocecal transit and satiation postnutrient challenge. The three arms were comparable with regard to age, gender and body mass index. There were no statistically significant effects of itopride on gastric emptying, orocecal transit, fasting gastric volume, maximum tolerated volume or aggregate symptom score with nutrient drink challenge. Postprandial (PP) change in gastric volume differed in the three groups (P = 0.019): 625[+/-28 (SEM)], 555(+/-26) and 512(+/-33) in placebo, itopride 100 and 200 mg groups, respectively. In healthy subjects, itopride reduced total PP gastric volume without accelerating gastric emptying or significantly altering gastric motor and sensory function in healthy individuals.

Challenges in drug development for functional gastrointestinal disorders. Part I: functional dyspepsia

There is a need to have predictive biomarkers to test novel experimental medicines in functional gastrointestinal disorders (FGID). The human pharmacodynamic models and biomarkers in functional dyspepsia (part I) and visceral pain (part II) are reviewed, including the general challenges of these two disorders (part I). Part II will also discuss the importance of drug pharmacokinetics and potential of pharmacogenomics, including the influence of CYP metabolism and potential drug interactions. The great heterogeneity of mechanisms potentially responsible for dyspeptic symptoms adds a significant complexity to this FGID. Strategies are needed to identify subgroups most likely to benefit from a specific pharmacological action targeted to one or more mechanisms. Thus, while there are significant challenges in drug development for functional dyspepsia, there is still an important role for pharmacodynamic studies. It remains to be demonstrated that identifying subgroups enhances the response to the pharmacological drug effect. This is feasible as the end points and performance of each test of gastric emptying, accommodation and sensitivity are well characterized. Of these, gastric emptying appears best validated at present, though responsiveness to this biomarker has not yet been translated into positive phase III trials. Eligibility criteria are proposed for selection of patients for functional dyspepsia trials.

Functional dyspepsia (FD) and non-erosive reflux disease (NERD): overlapping or discrete entities?

As the incidence of both gastric cancer and peptic ulcer disease have declined, that of gastro-oesophageal reflux disease (GORD) and non-ulcer, or functional dyspepsia (FD) have reached virtually epidemic proportions. As we come to appreciate the expression of these disorders in the community, the real spectrum of each disease has become evident. FD and non-erosive reflux disease (NERD), the most prevalent manifestation of GORD, frequently overlap. Where then does GORD end and FD begin? Is it realistic, or even clinically relevant, to attempt a clear separation between these entities? These are more than issues of mere semantics; therapeutic options may be dictated by the classification of the patient as one or the other. Recent work indicates clearly that NERD is a heterogeneous disorder incorporating some patients who may well harbour subtle manifestations of oesophagitis and others who have entirely normal 24-hour pH studies. These differences may be crucial to the concept of NERD/FD overlap. While evidence in support of this concept is far from complete, it would appear that this overlap is most relevant to those NERD patients who do not exhibit abnormal esophageal acid exposure. These patients truly belong in the spectrum of functional gastrointestinal disorders rather than in GORD; attempts to shoe-horn these individuals into the spectrum of GORD will result in therapeutic disappointment and surgical disaster.

Influence of a lipase inhibitor on gastric sensitivity and accommodation to an orally ingested meal

BACKGROUND

Intraduodenal administration of lipids, through lipid digestion and release of cholecystokinin (CCK), induces viscero-visceral reflexes that affect gastric tone and sensitivity. It is unclear whether the same mechanisms control gastric function after an orally ingested meal.

AIM

To evaluate the effect of orlistat, a selective lipase inhibitor, on gastric response to an orally administered meal.

METHODS

Eighteen healthy volunteers participated in this study. They were treated for 5 days with orlistat (120 mg) or placebo t.d.s. in a double-blind randomized crossover design. During treatment, all subjects underwent a gastric barostat study, measurement of plasma CCK levels and a satiety drinking test.

RESULTS

Although CCK plasma levels were significantly decreased, pre-treatment with orlistat failed to affect gastric compliance (72 +/- 6 mL/mm Hg and 64 +/- 6 mL/mm Hg, NS), gastric sensitivity (discomfort threshold 12.2 +/- 0.6 mm Hg vs. 10.9 +/- 0.6 mm Hg above minimal distending pressure, NS) or gastric accommodation (172 +/- 41 mL vs. 206 +/- 49 mL, NS) to an orally ingested meal. Furthermore, orlistat pre-treatment had no significant effect on the amount of calories ingested during a satiety drinking test (1329 +/- 88 kcal vs. 1217 +/- 115 kcal, NS).

CONCLUSION

Administration of a lipase inhibitor does not affect gastric compliance, sensitivity to distension and accommodation to an orally ingested meal, and does not influence meal-induced satiety.

Evaluation of drug treatment in irritable bowel syndrome

The irritable bowel syndrome (IBS) remains a therapeutic challenge in part because of the limited understanding of the pathophysiology. The placebo response rate varies in randomized controlled trials from 20 to 70%, and can persist for up to at least 1 year. It is contentious whether dietary fibre and bulking agents relieve the symptoms of IBS; constipation probably improves. Anticholinergic and antispasmodic agents are of questionable benefit in IBS despite positive meta-analyses of poor quality trials. A meta-analysis concluded that the tricyclic antidepressants were superior to placebo in IBS, although the individual trial results were variable. Selective serotonin reuptake inhibitors are of uncertain benefit. Laxatives are used for constipation but probably poorly control the IBS symptom complex. Loperamide is superior to placebo in improvement of diarrhoea but not abdominal pain in IBS. Tegaserod is a well- tolerated aminoguanidine indole derivative of serotonin that is a partial 5HT4-receptor agonist with prokinetic properties; a therapeutic gain over placebo of 5% to 15% has been observed in constipation-predominant IBS in females. Alosetron is a 5HT3-receptor antagonist that is efficacious in females with diarrhoea-predominant IBS, with a 12% to 17% therapeutic gain; the risk of ischaemic colitis is 1 in 350, with very severe constipation occurring in about 1 in 1000. Optimizing study design remains a challenge in IBS. New visceral analgesic and motility modifying agents, as well as anti-inflammatory agents are in trials, and hopefully additional efficacious therapeutic options for patients with IBS will soon emerge.

Time-resolved three-dimensional MR imaging of gastric emptying modified by IV administration of erythromycin

OBJECTIVE

The aim of our study was to assess the effect of IV erythromycin on gastric emptying and subsequent small-bowel filling using three-dimensional (3D) MR imaging in both healthy subjects and patients with functional dyspepsia.

SUBJECTS AND METHODS

Six healthy volunteers and six patients with symptoms of functional dyspepsia ingested 10 mL of gadopentetate dimeglumine mixed into 500 mL of a liquid nutrient. On two separate days, gastric emptying was determined using 3D volume measurements that were obtained every 5 min for as long as 25 min on 3D T1-weighted gradient-echo MR imaging with and without the use of IV erythromycin. Gastric volumes and filling of the small bowel were quantified on the 3D data sets using semiautomatic software.

RESULTS

Delineation of the bright gastric lumen proved easy. After 25 min, a significant decrease in gastric volumes could be seen in examinations performed with and without erythromycin. In healthy volunteers, gastric volumes decreased significantly more after the administration of erythromycin. In three patients with functional dyspepsia, MR imaging revealed reduced rates of gastric emptying. The administration of erythromycin resulted in a significantly faster rate of gastric emptying in two of those three patients.

CONCLUSION

Three-dimensional MR imaging is a feasible method of assessing gastric volumes and diagnosing delayed gastric emptying. In patients with reduced rates of gastric emptying, 3D MR imaging may be an appropriate tool with which to monitor therapeutic approaches, such as the use of prokinetic agents like erythromycin.

Serotonergic modulating drugs for functional gastrointestinal diseases

After many years of basic research we have now begun to learn how to manipulate the serotonergic mechanisms within the gut. This has lead to a number of significant advances including 5HT3 antagonists for the treatment of functional diarrhoea, 5HT4 agonists for the treatment of constipation and 5HT1 agonists for the treatment of impaired fundal relaxation. Initial enthusiasm has been somewhat dented by the withdrawal of alosetron because of ischaemic colitis, but it remains to be seen whether this adverse event will be seen with other 5HT3 antagonists. Finally it should be recognized that, in a substantial proportion of patients attending clinics complaining of functional symptoms, anxiety is a major component. The drugs so far described are by and large devoid of CNS effects. It remains possible therefore that a drug which combines both peripheral and central effects would likely to be beneficial.

Nonulcer Dyspepsia

There is currently no effective treatment for patients with nonulcer dyspepsia. Helicobacter pylori eradication has no beneficial effect on dyspeptic symptoms. Proton pump inhibitors are superior to placebo in the subset of patients with epigastric pain as the predominant symptom. H(2 )Receptor antagonists have no effect. Patients with dysmotility-like dyspepsia should be treated first with prokinetics. Unfortunately, cisapride no longer can be used to treat patients with functional dyspepsia because of reports of serious cardiovascular side effects and subsequent withdraw from the US market. Therefore, metoclopramide (or domperidone, if available) should be given. Treatment with motilides has no use in the relief of symptoms, even in patients with delayed gastric emptying. If the initial therapy has no effect after 4 weeks, switch treatment (eg, from proton pump inhibitor to metoclopramide or vice versa). If both of these pharmacologic therapies fail, consider treatment with an antidepressant (or with buspirone, an anxiolytic agent) or psychotherapy.