Erythromycin enhances fasting and postprandial proximal gastric tone in humans

Current and emerging pharmacotherapy for the treatment of gastroparesis

INTRODUCTION

Gastroparesis is a chronic disorder characterized by decreased gastric emptying and presents with nausea, vomiting, and abdominal pain which impacts patients' quality of life greatly. The treatment modalities available for gastroparesis have been expanding over the past 2 decades. Currently, there are multiple options available for gastroparesis, albeit with only one FDA-approved medication until June 2021.

AREAS COVERED

We review the different treatments available for gastroparesis and discuss the recently FDA-approved intranasal formulation of metoclopramide. This nasal spray guarantees metoclopramide absorption within 15 min of application bypassing first pass metabolism in the liver and overcoming the limitations of the oral formulation not passing into the small intestine for absorption because of a gastroparetic stomach or a patient unable to take the oral metoclopramide because of nausea and vomiting.

EXPERT OPINION

We now find ourselves in an oasis after spending many years in a 'desert' regarding pharmacologic therapies available for gastroparesis. The expansion of the research involving dopamine receptor antagonists and delving into alternative mechanisms of alleviating gastroparesis symptoms has been crucial in the landscape of gastroparesis. This is especially true as our knowledge of gastroparesis has proven that simply improving gastric emptying does not necessarily translate to clinical improvement.

Physiological functions and potential clinical applications of motilin

Motilin is a gastrointestinal hormone secreted by the duodenum. This peptide regulates a characteristic gastrointestinal contraction pattern, called the migrating motor complex, during the fasting state. Motilin also affects the pressure of the lower esophageal sphincter, gastric motility and gastric accommodation in the gastrointestinal tract. Furthermore, motilin induces bile discharge into the duodenum by promoting gallbladder contraction, pepsin secretion in the stomach, pancreatic juice and insulin secretion from the pancreas. In recent years, it has been shown that motilin is associated with appetite, and clinical applications are expected for diseases affected by food intake, e.g. obesity, by regulating motilin levels. Gastric acid and bile are the two major physiological regulators for motilin release. Caloric foods have varying effects on motilin levels, depending on their composition. Among non-caloric foods, bitter substances reduce motilin levels and are therefore expected to have an appetite-suppressing effect. Various motilin receptor agonists and antagonists have been developed but have yet to reach clinical use.

Macrolides for the prevention and treatment of feeding intolerance in preterm low birth weight infants: a systematic review and meta-analysis

The role of macrolides for the prevention and treatment of feeding intolerance (FI) in preterm low birth weight (LBW) infants has not been well established. To assess the efficacy and safety of macrolides to prevent or treat FI in preterm LBW infants. A systematic review and meta-analysis (PROSPERO ID: CRD42020170519) was conducted for English articles published since inception to March 2020, using MEDLINE, EMBASE, and the Cochrane Controlled Trials Register. Search terms included preterm low birth weight infants, macrolides, erythromycin, azithromycin, clarithromycin, and feeding intolerance. Randomized controlled trials (RCTs) assessing the effects of macrolide therapy on the time to achieve full enteral feeding (FEF;150 mL/kg/day), duration of parenteral nutrition (PN), hospitalization, and adverse events in preterm LBW infants were included. Independent extraction of data was done by both authors using predefined data-sheet. Very-low to low-quality evidence from 21 RCTs, 19 for erythromycin (prophylaxis-6, rescue-13) and 2 for clarithromycin (prophylaxis-1, rescue-1) demonstrated a significantly beneficial role of erythromycin for an earlier FEF, both as a prophylaxis (SMD-0.53, 95% CI - 0.74,- 0.33; 6 studies, n = 368) as well as rescue (SMD-1.16, 95% CI - 1.88, - 0.44; 11 studies, n = 664). Rescue therapy was also beneficial for a significant reduction in the duration of PN, hospitalization, incidences of sepsis, necrotizing enterocolitis, and cholestasis. No arrhythmia or infantile hypertrophic pyloric stenosis was reported.Conclusions: Erythromycin therapy, both as prophylaxis and rescue, is beneficial to reduce the time to achieve FEF in preterm LBW infants, at no higher risk of adverse events.Trial registration: PROSPERO ID: CRD42020170519.

Ultrasonographic assessment of the effect of metoclopramide, erythromycin, and exenatide on solid-phase gastric emptying in healthy cats

Background

Available data on the effect of gastrointestinal motility‐modifying drugs in cats are limited. Most recommendations for drug usage and dosage are based on collective clinical experience.

Objectives

To assess the effects of metoclopramide, erythromycin, and exenatide on gastric emptying (GE) and gastric motility in comparison to placebo. We hypothesized that metoclopramide and erythromycin would have prokinetic gastric effects, whereas exenatide would prolong GE times and decrease the motility index (MI) of antral contractions.

Animals

Eight healthy domestic shorthair cats.

Methods

Each cat had 4 separate ultrasonographic assessments. In a prospective, randomized, double‐blind, 4‐way crossover design, cats received placebo, metoclopramide, erythromycin, or exenatide for 2 days followed by a minimum 5‐day washout period. Ultrasonographic GE times and MI were compared to placebo.

Results

When compared to placebo, the rate of GE was significantly faster after administration of metoclopramide and erythromycin. Significant differences were found at all fractions of GE after administration of erythromycin and all but 1 fraction after metoclopramide when compared to placebo. The rate of GE in the first half of the GE curve was significantly slower after exenatide administration. The total area under the Ml curve was significantly larger after administration of metoclopramide and erythromycin than after placebo.

Conclusions and Clinical Importance

Metoclopramide and erythromycin shorten GE times and increase the MI of antral contractions, thus having a prokinetic effect in the stomach of healthy cats, whereas exenatide causes an initial delay in GE.

Motilin: from gastric motility stimulation to hunger signalling

After the discovery of motilin in 1972, motilin and the motilin receptor were studied intensely for their role in the control of gastrointestinal motility and as targets for treating hypomotility disorders. The genetic revolution - with the use of knockout models - sparked novel insights into the role of multiple peptides but contributed to a decline in interest in motilin, as this peptide and its receptor exist only as pseudogenes in rodents. The past 5 years have seen a major surge in interest in motilin, as a series of studies have shown its relevance in the control of hunger and regulation of food intake in humans in both health and disease. Luminal stimuli, such as bitter tastants, have been identified as modulators of motilin release, with effects on hunger and food intake. The current state of knowledge and potential implications for therapy are summarized in this Review.

Endoscopic control of gastric emptying after administration of intravenous erythromycin in an awake patient scheduled for urgent rigid bronchoscopy

Certain interventional pulmonology procedures such as the placement of a tracheal stent or resection of stenosing tracheal tumours require rigid bronchoscopy under general anaesthesia. Unlike an endotracheal tube with a cuff, the rigid bronchoscope only partially protects the airway from bronchoaspiration. For this reason, this procedure is performed on an elective basis in fasted patients. We describe the case of a 60-year-old man with acute respiratory distress requiring emergent rigid bronchoscopy following distal migration of a tracheal stent. One hour before the procedure, the patient had eaten a full meal. Gastric emptying was accelerated by perfusion of intravenous erythromycin and verified by endoscopy with a small diameter gastric endoscope under local anaesthesia. This 1 min procedure was very well tolerated by the patient and allowed to verify with certainty that the stomach was empty. The urgent rigid bronchoscopy for stent retrieval could then be performed safely without any risk of bronchoaspiration.

Gastric Motor Dysfunction in Patients With Functional Gastroduodenal Symptoms

OBJECTIVES

The pathophysiology of dyspeptic symptoms is complex. The aim of this study was to evaluate the association of gastric emptying (GE), gastric accommodation (GA), and respiratory sinus arrhythmia (RSA, to assess vagal dysfunction) in a large cohort with functional gastroduodenal symptoms.

METHODS

We reviewed demographic, clinical features, and results of gastric motor and vagal function studies of 1,287 patients (74.0% females, mean age 43.1±15.4 years) who had undergone both single photon emission computed tomography GA and scintigraphic GE. Accommodation was based on postprandial to fasting gastric volume ratio (VR). Electrocardiograms were available and analyzed for RSA in 300 patients.

RESULTS

There were 29.8% patients with normal GE and GA, 21.9% with abnormal GA only, 27.1% with abnormal GE only, and 21.1% with abnormal GA and GE. There were numerical differences in GA among patients with normal, accelerated, and delayed GE (P=0.062, by χ²). Increased GA (VR >3.85) was more prevalent in patients with delayed GE compared to accelerated GE (14.0% vs. 6.8%, P=0.004). Decreased VRs (median 2.9) were observed with accelerated GE compared to normal GE (median 3.1, P<0.05). Nausea and vomiting were more prevalent (in contrast to the less prevalent bloating) in patients with delayed compared to accelerated or normal GE (all P<0.05). In patients with diminished RSA, there was higher prevalence of reduced GA (41.5%) compared to those with preserved RSA (29.2%, P=0.031). Multivariable analysis showed associations of the main abdominal symptoms with gender, body mass index, gastric emptying, diabetes, and prior abdominal surgery.

CONCLUSIONS

Patients with symptoms of functional gastroduodenal disorders may have one or more gastric motor dysfunctions and reduced RSA; among the patients with abnormal gastric motor functions, vomiting suggests delayed GE, whereas reduced RSA is associated with reduced GA.

Pharmacological, Pharmacokinetic, and Pharmacogenomic Aspects of Functional Gastrointestinal Disorders

This article reviews medications commonly used for the treatment of patients with functional gastrointestinal disorders. Specifically, we review the animal models that have been validated for the study of drug effects on sensation and motility; the preclinical pharmacology, pharmacokinetics, and toxicology usually required for introduction of new drugs; the biomarkers that are validated for studies of sensation and motility endpoints with experimental medications in humans; the pharmacogenomics applied to these medications and their relevance to the FGIDs; and the pharmacology of agents that are applied or have potential for the treatment of FGIDs, including psychopharmacologic drugs.

Nausea: a review of pathophysiology and therapeutics

The sensation of nausea is a common occurrence with diverse causes and a significant disease burden. Nausea is considered to function as a protective mechanism, warning the organism to avoid potential toxic ingestion. Less adaptive circumstances are also associated with nausea, including post-operative nausea, chemotherapy-induced nausea, and motion sickness. A common definition of nausea identifies the symptom as a precursor to the act of vomiting. The interaction, though present, does not appear to be a simple relationship. Nausea is unfortunately the 'neglected symptom', with current accepted therapy generally directed at improving gastrointestinal motility or acting to relieve emesis. Improved understanding of the pathophysiological basis of nausea has important implications for exploiting novel mechanisms or developing novel therapies for nausea relief.

Completion rate of small bowel capsule endoscopy is higher after erythromycin compared to domperidone

Background

In up to 30 percent of small bowel capsule endoscopy procedures, the capsule does not reach the cecum within recording time. A prolonged gastric transit time has been recognized as a risk factor for incomplete capsule endoscopy. The aim of this study was to analyze if a single dose of orally administered erythromycin prior to capsule endoscopy results in a higher completion rate compared to orally administered domperidone.

Methods

Single centre, non-concurrent prospective cohort study, 649 capsule endoscopy procedures were included. Cecal completion rates, gastric and small bowel transit times and diagnostic yield were analyzed.

Results

239 patients received erythromycin, 410 patients received domperidone. The cecal completion rate was 86% after erythromycin versus 80% after domperidone (p = 0.03). After excluding known risk factors for incomplete capsule endoscopy such as hospitalization and previous abdominal surgery, erythromycin still resulted in an increased completion rate (p = 0.04). Median gastric transit time was lower after erythromycin compared to domperidone (13 min versus 22 min, p < 0.001). Median small bowel transit times were similar in both groups (236 min versus 248 min, p = 0.21).

Conclusions

In this study, the largest to date on this subject, the cecal completion rate was higher with erythromycin than with domperidone, but there was no difference in the diagnostic yield.

Anti-emetic and emetic effects of erythromycin in Suncus murinus: role of vagal nerve activation, gastric motility stimulation and motilin receptors

Paradoxically, erythromycin is associated with nausea when used as an antibiotic but at lower doses erythromycin activates motilin receptors and is used to treat delayed gastric emptying and nausea. The aim of this study was to characterise pro- and anti-emetic activity of erythromycin and investigate mechanisms of action. Japanese House musk shrews (Suncus murinus) were used. Erythromycin was administered alone or prior to induction of emesis with abnormal motion or subcutaneous nicotine (10mg/kg). The effects of erythromycin and motilin on vagal nerve activity and on cholinergically mediated contractions of the stomach (evoked by electrical field stimulation) were studied in vitro. The results showed that erythromycin (1 and 5mg/kg) reduced vomiting caused by abnormal motion (e.g., from 10.3 ± 1.8 to 4.0 ± 1.1 emetic episodes at 5mg/kg) or by nicotine (from 9.5 ± 2.0 to 3.1 ± 2.0 at 5mg/kg), increasing latency of onset to emesis; lower or higher doses had no effects. When administered alone, erythromycin 100mg/kg induced vomiting in two of four animals, whereas lower doses did not. In vitro, motilin (1, 100 nM) increased gastric vagal afferent activity without affecting jejunal afferent mesenteric nerve activity. Cholinergically mediated contractions of the stomach (prevented by tetrodotoxin 1 μM or atropine 1 μM, facilitated by l-NAME 300 μM) were facilitated by motilin (1-100 nM) and erythromycin (10-30 μM). In conclusion, low doses of erythromycin have anti-emetic activity. Potential mechanisms of action include increased gastric motility (overcoming gastric stasis) and/ or modulation of vagal nerve pathways involved in emesis, demonstrated by first-time direct recording of vagal activation by motilin.

Diagnostic yield of small bowel capsule endoscopy depends on the small bowel transit time

AIM: To investigate whether the small bowel transit time (SBTT) influences the diagnostic yield of capsule endoscopy (CE).

METHODS: Six hundred and ninety-one consecutive CE procedures collected in a database were analyzed. SBTT and CE findings were recorded. A running mean for the SBTT was calculated and correlated to the diagnostic yield with a Spearman’s correlation test. Subgroup analyses were performed for the various indications for the procedure.

RESULTS: There was a positive correlation between the diagnostic yield and SBTT (Spearman’s rho 0.58, P < 0.01). Positive correlations between diagnostic yield and SBTT were found for the indication obscure gastrointestinal bleeding (r = 0.54, P < 0.01), for polyposis and carcinoid combined (r = 0.56, P < 0.01) and for the other indications (r = 0.90, P <0.01), but not for suspected Crohn’s disease (r = -0.40).

CONCLUSION: The diagnostic yield in small bowel capsule endoscopy is positively correlated with the small bowel transit time. This is true for all indications except for suspected Crohn’s disease.

Preclinical electrogastrography in experimental pigs

Surface electrogastrography (EGG) is a non-invasive means of recording gastric myoelectric activity or slow waves from cutaneous leads placed over the stomach. This paper provides a comprehensive review of preclinical EGG. Our group recently set up and worked out the methods for EGG in experimental pigs. We gained our initial experience in the use of EGG in assessment of porcine gastric myoelectric activity after volume challenge and after intragastric administration of itopride and erythromycin. The mean dominant frequency in pigs is comparable with that found in humans. EGG in experimental pigs is feasible. Experimental EGG is an important basis for further preclinical projects in pharmacology and toxicology.

Gastric motor disturbances in patients with idiopathic rapid gastric emptying

BACKGROUND

The mechanisms of 'idiopathic' rapid gastric emptying, which are associated with functional dyspepsia and functional diarrhea, are not understood. Our hypotheses were that increased gastric motility and reduced postprandial gastric accommodation contribute to rapid gastric emptying.

METHODS

Fasting and postprandial (300kcal nutrient meal) gastric volumes were measured by magnetic resonance imaging (MRI) in 20 healthy people and 17 with functional dyspepsia; seven had normal and 10 had rapid gastric emptying. In 17 healthy people and patients, contractility was analyzed by spectral analysis of a time-series of gastric cross-sectional areas. Logistic regression models analyzed whether contractile parameters, fasting volume, and postprandial volume change could discriminate between health and patients with normal or rapid gastric emptying.

KEY RESULTS

While upper gastrointestinal symptoms were comparable, patients with rapid emptying had a higher (P=0.002) body mass index than normal gastric emptying. MRI visualized propagating contractions at ∼3cpm in healthy people and patients. Compared with controls (0.32±0.04, Mean±SEM), the amplitude of gastric contractions in the entire stomach was higher (OR 4.1, 95% CI 1.2-14.0) in patients with rapid (0.48±0.06), but not normal gastric emptying (0.20±0.06). Similar differences were observed in the distal stomach. However, the propagation velocity, fasting gastric volume, and the postprandial volume change were not significantly different between patients and controls.

CONCLUSIONS & INFERENCES

MRI provides a non-invasive and refined assessment of gastric volumes and contractility in humans. Increased gastric contractility may contribute to rapid gastric emptying in functional dyspepsia.

Proximal and overall gastric emptying of solids in patients with reduced gastric volume accommodation compared to matched controls

BACKGROUND

Interventions such as gastric surgery and erythromycin result in displacement of solids to the distal stomach and acceleration of overall and proximal gastric emptying. The effect of non-surgical impairment of gastric accommodation on gastric emptying is unclear. Non-surgical impairment of gastric accommodation is associated with accelerated gastric emptying.

AIM

To compare measurements of proximal and overall gastric emptying in patients with reduced postprandial gastric volume accommodation with the emptying rates in age- and gender-matched controls with normal postprandial gastric volume accommodation.

METHODS

We evaluated overall and proximal gastric emptying in nine patients with impaired gastric accommodation and age-equivalent and gender-matched controls. Gastric volumes and emptying were measured using validated SPECT and dual gamma camera scintigraphy, respectively. We compared group differences in overall and proximal gastric emptying t (1/2) by t test.

RESULTS

Patients with impaired postprandial gastric volume accommodation had greater fasting gastric volume. The proportion of food emptied from the proximal stomach immediately after meal ingestion was lower and t (1/2) of proximal gastric emptying correspondingly longer in the group with reduced postprandial gastric accommodation. In contrast, differences were not detected in overall gastric emptying in the two groups, and the ratio of overall to proximal gastric emptying t (1/2) was greater in the group with impaired volume accommodation.

CONCLUSIONS

Proximal stomach emptying is reduced in patients with impaired postprandial volume accommodation; this difference occurs predominantly during the time of meal ingestion. Compensatory mechanisms that result in normal overall gastric emptying require further elucidation.

Use of prokinetics in the preterm infant

PURPOSE OF REVIEW

Functional gastrointestinal dysmotility is a common condition that affects premature infants. Delay in achievement of full enteral nutrition results in dependence on prolonged parenteral nutrition, predisposing to adverse outcomes. Studies in recent years show apparently conflicting results regarding the use of prokinetic agents in preterm infants. This review aims to evaluate these studies to determine whether use of these agents in premature infants is beneficial and justified.

RECENT FINDINGS

Randomized controlled trials in recent years have been performed to investigate the effectiveness of erythromycin in the treatment of nonobstructive gastrointestinal dysmotility in preterm infants. Overall, neither low-dose regimes nor prophylactic trials have been shown to be useful. High-dose regimes used as rescue therapy of infants with established gastrointestinal dysmotility have consistently shown clinical benefit. Theoretical risks of prolonged antibiotic use, such as emergence of antibiotic resistance and abnormal intestinal microbiota, have not been fully evaluated.

SUMMARY

Judicious use of high-dose erythromycin in premature infants as rescue therapy is probably justifiable. Further research in this area is warranted to develop newer prokinetic agents which may improve the safety profile of therapy.

Influence of tegaserod on proximal gastric tone and on the perception of gastric distention in functional dyspepsia

BACKGROUND

Abnormalities in gastric sensorimotor function (hypersensitivity to distention and impaired meal accommodation) have been implicated in the pathophysiology of functional dyspepsia (FD). To study the effect of the 5-HT(4) agonist tegaserod on sensitivity to gastric distention and gastric accommodation in FD.

METHODS

Thirty FD patients (7 males, mean age 42 ± 2 years) underwent a gastric barostat study on two separate occasions, 2 weeks apart, after 5 days of pretreatment with placebo or tegaserod 6 mg b.i.d. in a double-blind randomized order. After introduction of the barostat bag, graded isobaric distentions (2 mmHg increments/2 min) were performed to determine gastric compliance and sensitivity to distention. Subsequently, the pressure level was set at intra-abdominal pressure [minimal distending pressure (MDP)] + 2 mmHg for 90 min, with administration of a liquid meal (200 mL; 300 kcal) after 30 min.

KEY RESULTS

Tegaserod had no influence on MDP (7.9 ± 0.4 vs 7.4 ± 0.4 mmHg) or fasting gastric compliance (44 ± 10 vs 61 ± 6 mL mmHg(-1)) and on fasting thresholds for first perception (3.6 ± 0.4 vs 4.2 ± 0.2 mmHg above MDP) or discomfort (9.9 ± 0.7 vs 10.5 ± 0.5 mmHg above MDP). Tegaserod did not alter intra-balloon volumes before and after the meal [respectively 146 ± 14 vs 120 ± 11 and 297 ± 28 vs 283 ± 29 mL, not significant (NS)], or the amplitude of the meal-induced gastric relaxation (151 ± 23 vs 162 ± 23 mL, NS). In the subgroup with normal gastric emptying (n = 22), tegaserod significantly enhanced meal-induced accommodation (126 ± 23 vs 175 ± 29 mL, ANOVA P < 0.001).

CONCLUSIONS & INFERENCES

Tegaserod does not alter gastric sensorimotor function in FD patients as a group. In the subgroup with normal gastric emptying, tegaserod 6 mg b.i.d enhanced gastric accommodation.

Effect of erythromycin before endoscopy in patients presenting with variceal bleeding: a prospective, randomized, double-blind, placebo-controlled trial

BACKGROUND

Blood in the stomach and esophagus in patients with variceal bleeding often obscures the endoscopic view and makes endoscopic intervention difficult to perform. Erythromycin, a motilin agonist, induces gastric emptying.

OBJECTIVE

To assess the effect of erythromycin on endoscopic visibility and its outcome in patients with variceal bleeding.

DESIGN

Randomized, double-blind, placebo-controlled trial.

SETTING

Tertiary care hospital.

PATIENTS

Adult patients with liver cirrhosis presenting with hematemesis within the previous 12 hours.

INTERVENTION

Either 125 mg erythromycin or placebo administered intravenously 30 minutes before endoscopy.

MAIN OUTCOME MEASUREMENTS

Endoscopic visibility during index endoscopy and mean duration of procedure. SECONDARY OUTCOME MEASUREMENTS: Need for repeat endoscopy and blood transfusions within 24 hours, endoscopy-related complications, and length of hospital stay.

RESULTS

A total of 102 patients received either erythromycin or placebo (53 erythromycin and 49 placebo). Forty-seven patients in the erythromycin group and 43 in the placebo group had variceal bleeding and were considered for final analysis. A completely empty stomach was seen in 48.9% of the erythromycin group versus 23.3% of the placebo group (P<.01). Mean endoscopy duration was significantly shorter in the erythromycin group than in the placebo group (19.0 minutes vs 26.0 minutes, respectively; P<.005). Length of hospital stay was significantly shorter in the erythromycin group than in the placebo group (3.4 days vs 5.1 days, respectively; P<.002). The need for repeat endoscopy and the mean number of units of blood transfused did not differ significantly in the 2 groups. No adverse events were observed with erythromycin.

LIMITATIONS

Sample size not sufficient to measure the need for repeat endoscopy and survival benefit.

CONCLUSIONS

Erythromycin infusion before endoscopy in patients with variceal bleeding significantly improves endoscopic visibility and shortens the duration of the index endoscopy. (

CLINICAL TRIAL REGISTRATION NUMBER

NCT01060267.).

Randomized controlled trial of a high dose of oral erythromycin for the treatment of feeding intolerance in preterm infants

OBJECTIVES

To evaluate the effectiveness of high-dose erythromycin to treat feeding intolerance in preterm infants predominantly fed milk formula.

DESIGN

This study is a prospective randomized controlled trial on 60 premature infants suffering from feeding intolerance. Thirty infants were given oral erythromycin ethylsuccinate at a dose of 50 mg/kg/day for 10 days or until they reached full enteral feeds. Randomization was stratified according to gestational age <32 weeks or ≥32 weeks gestation. The primary end point was the time taken to establish full enteral feeding since enrollment. Potential adverse effects associated with erythromycin were also monitored. Student's t test was used for comparison of continuous variables and χ(2)for categorical data.

RESULTS

In infants <32 weeks, the use of erythromycin was associated with more daily weight gain (12.8 ± 2.6 g vs. 9.2 ± 5.3 g, p = 0.04) compared to the control group. Time to reach full feed did not differ between the erythromycin (13.8 ± 3.9 days) and the control (17.46 ± 4.9 days) groups (p = 0.07). In infants ≥32 weeks, there were no differences between the erythromycin and the control groups.

CONCLUSION

High-dose erythromycin is associated with greater weight gain in preterm infants <32 weeks gestational age, who are predominantly fed cow's milk-based protein formulas.

The role of delayed gastric emptying and impaired oesophageal body motility

Delayed gastric emptying in a variable proportion of patients with gastro-oesophageal reflux disease has been observed in most series, however a relationship between delayed gastric emptying and increased gastro-oesophageal reflux has not been convincingly demonstrated. Enhanced postprandial accommodation and delayed emptying of the proximal stomach have been described, but some controversy exists. Impaired primary peristalsis is often present especially in patients with oesophagitis and its prevalence increases with increasing severity of inflammatory mucosal lesions. Patients with gastro-oesophageal reflux disease often have defective triggering of secondary peristalsis independently of presence of oesophagitis. It is presently unclear if impaired oesophageal motility is a primary defect or an irreversible consequence of inflammation. Attempts at pharmacological improvement of impaired oesophageal motility have been so far disappointing. Patients with partially preserved neuromuscular structures need to be identified in order to select them for new prokinetic therapy.

[Promotility drugs use in critical care: indications and limits?]

Enteral feeding is often limited by gastric and intestinal motility disturbances in critically ill patients, particularly in patients with shock. So, promotility agents are frequently used to improve tolerance to enteral nutrition. This review summaries the pathophysiology, presents the available pharmacological strategies, the clinical data, the counter-indications and the principal limits. The clinical data are poor. No study demonstrates a positive effect on clinical outcomes. Metoclopramide and erythromycin seems to be the more effective. Considering the risk of antibiotic resistance, the first line use of erythromycin should be avoided in favor of metoclopramide.

A novel method for study of gastric mechanical functions in conscious mice

A novel method has been developed for simultaneous study of gastric emptying, antral motility, and gastric muscle tone in conscious mice. Intragastric pressure was measured during infusion of an X-ray-opaque, viscous meal through a chronically implanted gastric fistula (0.25 ml/min). Compared with vehicle treatment, molsidomine (nitric oxide donor) and atropine (muscarinic receptor antagonist) treatment significantly reduced the area under the intragastric pressure curve (AUC) by 37 +/- 4% and 35 +/- 3%, respectively, (mean +/- S.E.M.) whereas N (G)-nitro-L-arginine methyl ester (L-NAME; nitric oxide synthase inhibitor) significantly increased the AUC by 20 +/- 3%. Atropine also significantly reduced the frequency and amplitude of stomach contraction-induced intragastric pressure waves while molsidomine only reduced the frequency. Gastric emptying, as assessed by X-ray imaging, was significantly delayed after L-NAME and atropine treatment. This methodology is the first to enable simultaneous assessment of gastric emptying, antral motility, and gastric tone in conscious mice and confirmed the important role of nitrergic and cholinergic innervation.

Current treatment of nausea and vomiting associated with gastroparesis: antiemetics, prokinetics, tricyclics

Gastroparesis is a symptomatic chronic disorder characterized by delayed gastric emptying without a mechanical obstruction. Gastroparesis is most often associated with diabetes, gastric surgery, and systemic disorders affecting the neuromuscular control of the stomach. However, no underlying etiology can be found in up to 40% of patients, a condition referred to as idiopathic gastroparesis. Due to the numerous potential etiologies and the highly variable clinical manifestations, the management of gastroparesis is particularly challenging. The purpose of this review is to provide an update on the use of antiemetics, prokinetics, and tricyclics for the treatment for nausea and vomiting associated with gastroparesis.

Effects of ginger on gastric emptying and motility in healthy humans

OBJECTIVE

Ginger has been reported to improve upper gastrointestinal symptoms. Little information about the effects of ginger on gastric motor function, exists, however. Our aim was to investigate the effects of ginger on gastric emptying, antral motility, proximal gastric dimensions, and postprandial symptoms.

METHODS

Twenty-four healthy volunteers were studied twice in a randomized double-blind manner. After an 8 h fast, the volunteers ingested three ginger capsules (total 1200 mg) or placebo, followed after 1 h by 500 ml low-nutrient soup. Antral area, fundus area and diameter, and the frequency of antral contractions were measured using ultrasound at frequent intervals over 90 min, and the gastric half-emptying time was calculated from the change in antral area. Gastrointestinal sensations and appetite were scored using visual analog questionnaires. Data are expressed in terms of mean+/-standard error.

RESULTS

Antral area decreased more rapidly (P<0.001) and the gastric half-emptying time was less after ginger than placebo ingestion (13.1+/-1.1 vs. 26.7+/-3.1 min, P<0.01), whereas the frequency of antral contractions was greater (P<0.005). Fundus dimensions did not differ, and there was no significant difference in any gastrointestinal symptoms.

CONCLUSION

Ginger accelerates gastric emptying and stimulates antral contractions in healthy volunteers. These effects could potentially be beneficial in symptomatic patient groups.

Effect of erythromycin on image quality and transit time of capsule endoscopy: A two-center study

AIM: To compare the effect of oral erythromycin vs no preparation with prokinetics on the transit time and the image quality of capsule endoscopy (CE) in evaluating small bowel (SB) pathology.

METHODS: We conducted a retrospective, blinded (to the type of preparation) review of 100 CE studies, 50 with no preparation with prokinetics from one medical center (Group A) and 50 from another center with administration of a single dose of 200 mg oral erythromycin 1 h prior to CE (Group B). Gastric, SB and total transit times were calculated, the presence of bile in the duodenum was scored, as was cleanliness within the proximal, middle and distal intestine.

RESULTS: The erythromycin group had a slightly shorter gastric transit time (21 min vs 28 min, with no statistical significance). SB transit time was similar for both groups (all P > 0.05). Total transit time was almost identical in both groups. The rate of incomplete examination was 16% for Group A and 10% for Group B (P = 0.37). Bile and cleanliness scores in different parts of the intestine were similar for the two groups (P > 0.05).

CONCLUSION: Preparation for capsule endoscopy with erythromycin does not affect SB or total transit time. It tends to reduce gastric transit time, but it does not increase the cecum-reaching rate. Erythromycin does not adversely affect image quality. We consider the routine use of oral erythromycin preparation as being unjustified, although it might be considered in patients with known prolonged gastric emptying time.

A novel method to assess gastric accommodation and peristaltic motility in conscious rats

OBJECTIVE

To simultaneously study gastric accommodation and peristaltic motility in the whole stomach of conscious rats by measuring intragastric pressure (IGP) during test-meal infusion.

MATERIAL AND METHODS

After an overnight fast, a test-meal infusion system and a catheter to measure IGP were connected to a chronically implanted gastric fistula. IGP was measured during infusion of an X-ray-opaque, non-nutritious viscous test meal (0.25-2 ml min(-1)); gastric motility and emptying were assessed by X-ray fluoroscopy. Peristaltic motility-induced IGP waves were quantified as a motility index (wave amplitude divided by wavelength). Experiments were performed in Sprague-Dawley (SD) rats and in the high-anxiety Wistar Kyoto (WKY) rats. Moreover, the effects of 30 mg kg(-1) NG-nitro-L-arginine methyl ester (L-NAME), 1 mg kg(-1) atropine or 20 mg kg(-1) molsidomine were tested in SD rats.

RESULTS

Compared with SD rats, IGP increased significantly faster during stomach distension in WKY rats, indicating impaired accommodation in the latter strain. Motility indices did not differ between the two strains. L-NAME significantly increased IGP during stomach distension, indicating decreased gastric accommodation. However, no change in motility indices was observed with L-NAME. Treatment with atropine significantly increased IGP and decreased motility indices, indicating decreased gastric accommodation and motility. Molsidomine significantly decreased IGP during stomach distension but did not affect motility. The results correspond to X-ray observations, and confirm literature data.

CONCLUSIONS

We conclude that IGP measurement during test-meal infusion represents an efficient and novel method to compare gastric accommodation and peristaltic motility in the whole stomach of conscious rats.

High-dose oral erythromycin decreased the incidence of parenteral nutrition-associated cholestasis in preterm infants

BACKGROUND & AIMS

Feeding intolerance because of functional gastrointestinal dysmotility and parenteral nutrition-associated cholestasis (PNAC) are common problems in preterm, very-low-birth-weight (VLBW) infants. This double-blind, randomized, placebo-controlled study aimed to assess the effectiveness of "high-dose" oral erythromycin as a prokinetic agent in decreasing the incidence of PNAC. Two secondary end points, including the time to achieve full enteral feeding and the duration of parenteral nutrition, were also evaluated.

METHODS

Infants consecutively admitted to the neonatal unit were randomized to receive erythromycin (12.5 mg/kg/dose every 6 hours for 14 days) or an equivalent volume of normal saline (placebo) if they attained less than half the total daily fluid intake (<75 mL/kg/day) as milk feeds on day 14 of life.

RESULTS

Of 182 VLBW infants enrolled, 91 received erythromycin. The incidence of PNAC was significantly lower in erythromycin-treated infants (18/91) compared with placebo infants (37/91; P = .003). Treated infants achieved full enteral nutrition significantly earlier (mean, 10.1; SE, 1.7 days; P < .001), and the duration of parenteral nutrition was also significantly decreased by 10 days (P < .001). Importantly, fewer infants receiving erythromycin had 2 or more episodes of septicemia (n = 4) compared with placebo patients (n = 13, P = .03). No serious adverse effect was associated with erythromycin treatment.

CONCLUSIONS

High-dose oral erythromycin can be considered as a rescue measure for VLBW infants who fail to establish adequate enteral nutrition and in whom anatomically obstructive pathologies of the gastrointestinal tract have been excluded.

Dysaccommodation of the stomach: therapeutic nirvana?

Functional dyspepsia (FD) is a highly prevalent gastrointestinal disorder and has a complex pathophysiology. Impaired fundic relaxation in response to a meal is present in 40% of patients with FD. This review focuses on impaired gastric accommodation of the stomach as a pathophysiological mechanism and the possible therapeutic targets that can be derived from the current knowledge of the neuroregulation of the accommodation reflex. First the different means of gastric accommodation assessment are described and the relationship between symptoms and impaired gastric accommodation. The different therapeutic options are subsequently discussed in view of their molecular target, based on the different receptor subtypes involved in the accommodation reflex. Although impaired gastric accommodation is highly prevalent in dyspeptic patients and basic knowledge about the accommodation reflex enables to develop pathophysiologically targeted therapies, it is unlikely that therapies aimed at dysaccommodation of the stomach will lead to symptom relief in all dyspeptic patients. A major challenge is the development of methods that readily identify impaired accommodation in clinical practice.

Erythromycin and feeding intolerance in premature infants: a randomized trial

OBJECTIVES

To evaluate the effectiveness of low-dose oral erythromycin to treat feeding intolerance in preterm infants.

DESIGN

This study was a prospective, double-blind, randomized, placebo-controlled trial on 60 premature infants suffering from feeding intolerance. Thirty infants were given oral erythromycin 1 mg/kg every 8 h and 30 infants were given placebo (normal saline). Randomization was stratified on enrollment according to gestational age whether >32 weeks or <or=32 weeks. The primary end point was the length of time taken to establish full enteral feeding since enrollment. Potential adverse effects associated with erythromycin were also monitored. Groups of each corresponding stratum were compared using two-tail t-test and Mann-Whitney for continuous variables, and chi (2) and Fisher's exact for categorical variables.

RESULTS

For infants with gestational age >32 weeks, the erythromycin group achieved full enteral feeding earlier than placebo group (10.5+/-4.1 vs 16.3+/-5.7 days, respectively; P=0.01) had fewer episodes of gastric residuals (P<0.05) and shorter duration of parenteral nutrition (PN) (P<0.05). On the other hand, in infants with gestational age <or=32 weeks, there were no significant differences between erythromycin and placebo groups regarding any of these variables.

CONCLUSION

Low-dose enteral erythromycin is associated with better tolerance of feeding and shorter duration of PN in infants >32 weeks gestation. A similar effect on younger preterm infants was not demonstrable.

Neostigmine-induced postprandial phasic contractility in the proximal stomach and dyspepsia-like symptoms in healthy volunteers

BACKGROUND AND AIMS

In a subset of functional dyspepsia patients, we have recently described the association between unsuppressed postprandial phasic contractions of the proximal stomach and a specific symptom pattern. To better elucidate the role of phasic contractility of the proximal stomach in symptom generation, we aimed at inducing this motility pattern in healthy volunteers and we carefully monitored symptom onset.

PATIENTS AND METHODS

Eleven healthy volunteers underwent gastric barostat on two separate days. Gastric tone and phasic contractility were evaluated for a 90-minute period. In particular, after 30 min of basal recording, a caloric liquid meal and neostigmine 0.5 mg IV or saline in a double-blind, randomized, crossover protocol were administered. During the measurement, severity of 9 dyspeptic symptoms was evaluated on a visual analog scale. Computer-aided baseline reconstruction allowed us to quantify phasic contractions as a motility index (MI), reflecting the area between signal and baseline normalized over time. Perception of contractions after placebo or neostigmine was evaluated. Moreover, we tested for influence of gastric tone and phasic contractility on symptoms.

RESULTS

After neostigmine, gastric accommodation was not different than after placebo (225 +/- 36 vs 206 +/- 76 mL, P= NS). During the first 30-min postprandial period, the MI was significantly higher after neostigmine than after placebo (26.4 +/- 3 vs 21.4 +/- 3, P < 0.001), confirming the induction of unsuppressed postprandial phasic contractions. The postprandial total symptom score was significantly higher after neostigmine compared to saline; several individual postprandial symptom scores were also significantly higher after neostigmine-compared placebo. After neostigmine, a higher percentage of postprandial contractions was perceived compared to placebo.

CONCLUSIONS

Unsuppressed postprandial phasic contractility of the proximal stomach is a mechanism potentially involved in the pathogenesis of dyspeptic symptoms.

Obesity does not increase effects of synthetic ghrelin on human gastric motor functions

BACKGROUND & AIMS

Ghrelin is secreted by the stomach and stimulates food intake. Obese individuals have lower fasting plasma ghrelin levels but increased appetite, suggesting greater responses to endogenous ghrelin in obesity. The aim of this study was to compare effects of exogenous ghrelin (at a dose that stimulates growth hormone [GH] release in the physiologic range) versus placebo on gastric emptying, gastric volume, and postprandial symptoms and determine whether body mass (ranging from normal weight to obesity) influences responses to ghrelin.

METHODS

After intravenous bolus synthetic human ghrelin (0.33 mug/kg) or saline, we measured plasma GH, gastric volume, and gastric emptying by combined (99m)Tc-single-photon emission computed tomography and scintigraphy ((111)In egg meal, 300 kcal) and postprandial symptoms using visual analogue scales.

RESULTS

In 25 obese subjects (5 men and 20 women; body mass index [BMI], 36 +/- 4 kg/m(2)) and 13 female normal-weight (BMI, 22 +/- 2 kg/m(2)) subjects of similar ages, ghrelin increased GH levels (15.0 +/- 2.4 ng/mL) at 40 minutes postinjection and tended to decrease fasting gastric volumes compared with placebo (P = .059). There were no effects of BMI on treatment response and no differences between ghrelin and saline on postprandial (P = .09) or change in (postprandial minus fasting) gastric volumes, gastric emptying, or aggregate postprandial symptoms. Effects of ghrelin did not differ between obese and normal-weight participants.

CONCLUSIONS

At doses that stimulate physiologic GH plasma levels, synthetic ghrelin tended to decrease fasting gastric volumes without altering postprandial volumes or gastric emptying in a predominantly female cohort. The data are not consistent with the hypothesis that higher body mass is associated with increased gastric responsiveness to ghrelin.

Wistar Kyoto rats have impaired gastric accommodation compared to Sprague Dawley rats due to increased gastric vagal cholinergic tone

OBJECTIVE

Gastric balloon distension shows that, in comparison with Sprague Dawley (SD) rats, Wistar Kyoto (WKY) rats have a decreased volume response owing to a lower accommodation rate. The aim of this study was to compare the role of the vagal cholinergic and nitrergic pathways in the accommodation reflex in these rat strains.

MATERIAL AND METHODS

The volume response to ramp-tonic gastric balloon distension was pharmacologically manipulated by using L-NAME 25 mg/kg i.v., molsidomine 20 mg/kg i.p., atropine 1 mg/kg i.v. and clonidine 0.7 mg/kg s.c.

RESULTS

Following L-NAME, the maximal volume response to distension was significantly decreased in WKY rats (0.74+/-0.11 ml versus 1.18+/-0.13 ml) whereas only a tendency to such a decrease was seen in SD rats. The NO donor molsidomine significantly increased the volume in SD rats (4.91+/-0.46 ml versus 1.81+/-0.50 ml) but only weakly in WKY rats. Atropine significantly increased the gastric volume in WKY rats (2.78+/-0.29 ml versus 1.00+/-0.17 ml) but not in SD rats. Clonidine increased the accommodation rate in the WKY rat, resulting in increased maximal volume (1.69+/-0.26 ml versus 0.65+/-0.11 ml) indicating a reduction in acetylcholine release as a consequence of stimulated presynaptic adrenergic receptors on cholinergic neurons.

CONCLUSIONS

The results indicate that WKY rats may have an increased gastric vagal cholinergic drive, which, during distension, masks the relaxing effect of NO-releasing neurons. The findings in WKY rats could be of relevance for functional dyspeptic patients with impaired gastric accommodation to meals.

Erythromycin Promotes Gastric Emptying During Acute Pain in Volunteers

In this double-blind cross-over study, we assessed whether erythromycin infusion is effective as a prokinetic drug against gastroparesis from acute pain. The effect of erythromycin on gastric emptying (GE) was measured in seven volunteers subjected to a standardized acute painful stimulus. The GE rate for solids was measured using the octanoic acid breath test. An acetaminophen absorption test measured the GE rate for liquids. Five minutes after ingestion of a 13C-labeled meal, the subjects received in randomized order either a test (placebo and erythromycin groups) or a control (control group) stimulus consisting of repeated 1-min immersion of a hand into 4 degrees C (test) or 37 degrees C (control) water, with 15 s for recovery between immersions, for a total of 20 min. While the stimulus was applied, 250 mL saline (control and placebo groups) or 250 mg erythromycin (erythromycin group) was infused. Pain and stress were evaluated using visual analog scales, and standard hemodynamic values were recorded throughout the study. Our results show that acute stress decreased GE for solids, which was significantly accelerated in the erythromycin group in comparison with the placebo group. GE for liquids was similar in the three groups. We conclude that erythromycin is effective as a prokinetic drug for solids in acute painful situations.

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.

Influence of motilin on gastric fundus tone and on meal-induced satiety in man: role of cholinergic pathways

BACKGROUND

Motilin agonists are strong gastroprokinetics, but their impact on symptoms in delayed gastric emptying has been disappointing. It has been speculated that it is due to the contractile effect of motilin agonists on the proximal stomach, but the pathway involved and the symptomatic consequences have been incompletely elucidated.

AIMS

To study whether motilin enhances proximal stomach tone and enhances meal-induced satiety and to evaluate whether this effect involves a cholinergic pathway.

METHODS

A gastric barostat was used to study, in healthy subjects, the effect of motilin (300 ng/kg/30 min i.v.) or saline on fasting gastric fundus tone and on post-prandial relaxation. To evaluate the involvement of a cholinergic pathway, atropine (12 microg/kg/h) was administered intravenously simultaneously with or before and during motilin infusion in the fasting state. Finally, a satiety drinking test was performed in 21 subjects twice after pretreatment with placebo or motilin and with placebo or atropine.

RESULTS

Administration of motilin caused a significant increase of fasting fundus tone expressed as decrease of the mean balloon volume (324 +/- 60 mL vs 213 +/- 62 mL, p < 0.05). Simultaneous administration of atropine and motilin did not generate a significant volume change (192 +/- 60 mL vs 181 +/- 83 mL, NS), but pretreatment with atropine alone induced a relaxation, and when motilin was added this revealed an ongoing contraction (192 +/- 24 mL vs 136 +/- 21 mL, p < or = 0.05). Motilin infusion also inhibited gastric accommodation (p < or = 0.05 vs placebo) and increased satiety during a satiety drinking test (p < or = 0.05 vs placebo).

CONCLUSIONS

Administration of motilin causes a contraction of the proximal stomach in humans and increases meal-induced satiety. The effect of motilin is atropine-resistant and involves a direct muscular pathway or a non-cholinergic neural pathway.

[Experimental study of the influence of the segmental transverse colic reversion on the intestinal transit time]

OBJECTIVE

to study the feasibility of the transverse segment colic reversion and to evaluate its impact on the intestinal transit time in the rat Wistar.

METHOD

On a test group of the rats Wistar males anaesthetized, we isolated a segment from the transverse colon vascularized by a feeder pedicle. This segment colic was reversed and anastomosed into antiperistaltic out of termino-terminal on its site with polyglactine 6/0. Into post-operative, we studied, the weight, the volume of the ingestats, the intestinal transit time, the survival and the histological lesions of the reversed segment colic. On the group controls, we carried out the anastomosis of a segment of the transverse colon isolated and anastomosed into isoperisaltic.

RESULTS

Thirty rats males of 231.5 +/- 8.3g had been operated, 15 for the test group and 15 for the control group. The average weight of the ingestats of the rats of the test group was of 21.87 +/- 3g and of 21.75 +/- 4.8g in the control group without significant difference. The intestinal transit occured at 3 +/- 1 post-operatives days in the test group and at 2 postoperative days in the control group. A mechanical obstruction of the bowels before the 15th post-operative day involved a mortality of 87% in the test group. Thirteen percent of the rats of the test group survived, with a regular catch of weight. The histological analysis showed inflammatory lesions on the proximal portion of the reversed segment and a normal wall without ischaemic injury on its distal portion. No death was observed in the group controls.

CONCLUSION

The antiperistaltic anastomosis of a transverse segment colic within the colic in the rat Wistar, causes a stop of the intestinal transit time by mechanical occlusion without ischaemic lesion of the segment colic reversed.

Promotility medications--now and in the future

Gastrointestinal promotility drugs stimulate smooth muscle contractions to enhance gastric emptying and small and large bowel transit. Currently available drug classes with prokinetic properties include antidopaminergic agents, serotonergic agents, and motilin-receptor agonists. Due to moderate prokinetic effects, poor symptomatic responses and the presence of adverse effects, there is a clear need for new classes of prokinetics. Several newer prokinetic drugs and drug classes are currently under evaluation. Selecting candidate agents and designing the appropriate therapeutic trials is hampered by the lack of insight in the pathophysiology of motility-related symptoms. As gastrointestinal motor disorders are chronic, relapsing, and remitting disorders, it seems desirable that studies with candidate prokinetic drugs establish a long-term efficacy and not only short-term effects on gastrointestinal functions.

Effect of atilmotin on gastrointestinal transit in healthy subjects: a randomized, placebo-controlled study

We studied effects of i.v. atilmotin (BAX-ACC-1638, a novel motilin agonist, circulating t(1/2) < 10 min) on gastrointestinal transit in humans using a randomized, parallel-group, dose-response double-blind study of i.v. atilmotin, 6, 30, 60 microg or vehicle (placebo) given 2 min after standardized breakfast, lunch and dinner. The breakfast meal contained (99m)Tc-eggs and (111)In-milk. Full gastrointestinal transit was measured by scintigraphy. Primary endpoints were % gastric emptying (GE) at 30 min, GE t(1/2), colonic filling (CF) at 6 h, and geometric centre of colonic transit at 24 h. Analysis included adjustment for age, gender and body mass index, with Bonferroni correction applied for multiple comparisons. A significant treatment effect of atilmotin was detected for GE (%) at 30 min for solids and liquids (P < 0.01 for both). There were no significant effects on CF or CT and no significant adverse clinical events. Thus, atilmotin accelerates GE of solids and liquids in healthy humans. These data suggest that, at the doses tested, atilmotin should be considered for treatment of stomach motility disorders.

Pathophysiology and treatment of functional dyspepsia

Functional dyspepsia is a highly prevalent symptom complex and a heterogenous disorder. Recent studies showed potential associations between specific pathophysiologic disturbances and dyspeptic symptoms. Delayed gastric emptying reported in about 30% of patients with functional dyspepsia is associated with the symptoms of postprandial fullness, nausea, and vomiting. Impaired gastric accommodation present in 40% of functional dyspepsia patients is found to be associated with early satiety. Hypersensitivity to gastric distension is observed in 37% of functional dyspepsia patients and associated with the symptoms of postprandial pain, belching, and weight loss. Psychosocial factors and altered response to duodenal lipids or acid have also been identified as pathophysiologic mechanisms. Therapeutic options are still limited but targeted therapy directed at the underlying pathophysiology seems desirable. Thus, efforts to further elucidate underlying pathophysiologic mechanisms and identify the appropriate patient population using some type of pathophysiologic testing will be required.

Idiopathic dyspepsia

Idiopathic dyspepsia refers to pain and/or discomfort perceived in the epigastrium that is not secondary to organic, systemic, or metabolic diseases. Symptoms may overlap with those of gastroesophageal reflux disease and irritable bowel syndrome. Gastrointestinal motor disorders, hypersensitivity to mechanical or chemical stimuli, and psychosocial factors can act individually or in concert to induce the symptoms of dyspepsia. Accordingly, there is no single therapy, and treatment must be individualized. Eradication of Helicobacter pylori infection rarely achieves symptom improvement. Treatment of idiopathic dyspepsia should begin by reassuring the patient about the benign nature of the syndrome and educating them on the knowledge that has been achieved in recent years regarding potential causes of the syndrome. Both prokinetic and antisecretory drugs have been reported to improve dyspeptic symptoms, but results are not completely convincing. Although well-designed studies demonstrate superiority of proton pump inhibitors over placebo, it should be noted that patients with nonerosive gastroesophageal reflux disease were invariably included; when these patients are excluded, the benefit of antisecretory medications is questionable. We suggest that patients with idiopathic dyspepsia be initially treated according to the predominant symptom. Those with epigastric pain/burning should receive a trial with standard doses of proton pump inhibitors for 4 to 8 weeks, whereas prokinetic patients should be prescribed at recommended doses for similar periods of time to patients with nonpainful dyspeptic symptoms such as posprandial fullness, early satiety, nausea, or vomiting. Nonresponders may benefit from combination therapies or short trials with higher doses of drugs. Visceral analgesics and antidepressants can also be prescribed alone or in combinations with other therapeutic strategies. Recent studies demonstrate utility for psychologic therapy and hypnotherapy, although truly controlled studies are difficult in this area. Herbal medicines deserve further evaluation.

Desensitization of the Human Motilin Receptor by Motilides

Tachyphylaxis may have contributed to the failure of the motilide ABT-229 [N-ethyl, N-methyl 4'' deoxy erythromycin (EM)-B enolether] in clinical trials. We compared the desensitizing potency of structurally related motilides [EM-A, EM-A enolether (ME4), N-ethyl, N-methyl EM-A (ME36), EM-B enolether (ME67), N-ethyl, N-methyl EM-A enolether (EM523), ABT-229 and 4'' deoxy EM-A enolether (KOS1326)] in a Chinese hamster ovary (CHO)-K1 cell line expressing the human motilin receptor (MTLR) and in rabbit duodenal segments. CHO-MTLR cells were preincubated with motilides prior to stimulation with motilin. The negative logarithm of the preincubation concentration reducing the maximal motilin-induced Ca(2+) flux to 50% was calculated (pDC(50)). Internalization was visualized in CHO-K1 cells containing an enhanced green fluorescent protein (EGFP)-tagged MTLR and quantified in binding experiments. The contractile response of repeated stimulations was measured in duodenal segments. In CHO-MTLR cells, the pDC(50) was ABT-229 (8.78) > motilin (7.77) > EM-A (4.78), different from their order of potency to induce Ca(2+) release (pEC(50)): motilin (9.39) > ABT-229 (8.46) > EM-A (7.11). In cells with the EGFP-tagged MTLR, ABT-229 decreased membrane fluorescence by 25 +/- 2% compared with 16 +/- 2% for motilin and 8 +/- 2% for EM-A. Binding studies confirmed that EM-A did not induce MTLR internalization (residual binding 96 +/- 4% compared with motilin, 31 +/- 3% and ABT-229, 21 +/- 1%). Comparison of the pDC(50) and pEC(50) values of the other motilides ME4 (5.90; 8.08), ME67 (6.03; 8.12), ME36 (3.32; 6.62), EM-523 (6.02; 8.22), and KOS1326 (7.32; 8.14) suggested that the strong desensitizing properties of ABT-229 are mostly related to the removal of the 4''-OH of the cladinose sugar. The decline of the contractile response in duodenal segments correlated with the pDC(50). The ability to desensitize and internalize the MTLR is not only determined by potency. This may be an important criterion for the development of a clinically useful compound.

Proximal gastric dysfunction in functional dyspepsia: Management options

Functional dyspepsia is a heterogeneous disorder where distinct pathophysiological abnormalities are present in subgroups of patients. Accommodation of the proximal stomach to a meal is impaired in up to half of the patients with functional dyspepsia. This is associated with symptoms of early satiety and weight loss. Drug interventions aimed at restoring impaired accommodation are currently being studied.

Erythromycin in the short- and long-term control of dyspepsia symptoms in patients with gastroparesis

BACKGROUND

Few prokinetic drugs are available to treat gastroparesis. Data are limited on short-term and long-term efficacy of erythromycin as a prokinetic drug.

GOALS

Assess efficacy of low-dose erythromycin suspension to treat gastroparesis.

STUDY

Patients with dyspepsia and gastroparesis by gastric emptying study were treated with low-bulk diet and low-dose (50-100 mg 3 times a day and at bedtime) oral erythromycin suspension. Data were collected by retrospective chart review and telephone questionnaire for short- and long-term follow-up, respectively.

RESULTS

Of 25 patients, 18 had short-term follow-up, 18 had longterm follow-up, and 14 had both. On short-term follow-up, 15 patients (83%) experienced some or dramatic improvement, while 3 (17%) experienced worsening or no change in symptoms (P = 0.005). Mean duration of long-term use was 11 +/- 7 months. On long-term followup, 12 (67%) patients noticed some or dramatic improvement, while 6 (33%) experienced worsening or no change in symptoms (P = 0.16). Correlation (0.7) between short- and long-term response was significant (P < 0.005). Of the 3 patients with poor short-term response, none did well long term. Of the 11 patients with some or dramatic response in short-term, 7 continued to have some response long term. There was no relation between gastric emptying time and response to erythromycin suspension.

CONCLUSIONS

Treatment of gastroparesis with low-dose erythromycin and low-bulk diet results in a dramatic short-term improvement in the majority of patients. Short-term response predicts long-term response. This response may not be as great, possibly due to tachyphylaxis.

Mechanoreceptors of the proximal stomach: Role in triggering transient lower esophageal sphincter relaxation

BACKGROUND AND AIMS

The role of fundic tension and stretch mechanoreceptors in triggering transient lower esophageal sphincter (LES) relaxation is still unknown. This information would be useful for the development of effective pharmacologic strategies. To elucidate this topic, gastric contractile activity was modified during isovolumetric gastric distention at 2 different volumes.

METHODS

LES (Dentsleeve) and gastric (barostat) motility were recorded in 21 healthy subjects during studies comprising two 30-minute isovolumetric gastric distentions (placebo and glucagon or erythromycin). Glucagon (bolus of 4.8 microg/kg plus infusion of 9.6 microg x kg(-1) x h(-1)) was administered at high intragastric volume (i.e., 75% of the threshold volume for discomfort; n = 7) and erythromycin (3 mg/kg) at high (n = 7) and low intragastric volume (i.e., at perception threshold; n = 7).

RESULTS

Glucagon decreased (P < 0.05) baseline intragastric pressure and abolished gastric contractions (0 vs. 16.7 +/- 2.3), whereas erythromycin increased (P < 0.05) baseline pressure and doubled (P < 0.05) the rate of gastric contractions at both volumes. Neither drug affected the rate of transient LES relaxations. Low intragastric volume induced a lower rate of transient LES relaxations (1.7 +/- 0.3 vs. 5.7 +/- 1.1; P < 0.01) and gastric contractions (11.8 +/- 2.5 vs. 20.5 +/- 3.1; P < 0.05) compared with high volume but similar baseline intragastric pressure (10.6 +/- 0.6 vs. 11.9 +/- 0.9 mm Hg).

CONCLUSIONS

Stretch receptors (gastric volume) seem to be more relevant than tension receptors in triggering transient LES relaxation.

Influence of tegaserod on proximal gastric tone and on the perception of gastric distension

BACKGROUND

Tegaserod, a 5-hydroxytryptamine-4 receptor agonist, enhances gastric emptying, but its effects on proximal stomach function have not been studied.

AIM

To study the effect of tegaserod on gastric compliance, accommodation and perception of distension in humans.

METHODS

Nineteen healthy volunteers (10 females; mean age, 23.9 years) were studied on three separate occasions after 7 days of treatment with placebo, tegaserod 2 mg b.d. or tegaserod 6 mg b.d. in a double-blind, randomized, three-way cross-over design. After the introduction of a barostat bag, stepwise distensions were performed to determine gastric compliance and sensitivity, and a mixed liquid meal was administered in isobaric mode to assess accommodation.

RESULTS

Tegaserod had no effect on the pressures or volumes inducing first perception or discomfort. Tegaserod 6 mg b.d. enhanced fasting gastric compliance compared with placebo. Pre-prandial and post-prandial intra-balloon volumes were significantly higher after 6 mg b.d. than after placebo. Both tegaserod 2 and 6 mg b.d. shortened the time to maximum post-prandial intra-balloon volume. The amplitude of meal-induced gastric relaxation (post-prandial minus pre-prandial volumes) did not differ between the treatment arms.

CONCLUSION

In humans, tegaserod allows for larger intra-balloon volumes both before and after a meal. These findings warrant the investigation of the therapeutic potential of tegaserod in dyspeptic patients with impaired accommodation.

Erythromycin induces pyloric relaxation accompanied by a contraction of the gastric body after pylorus-preserving gastrectomy

BACKGROUND

Pylorus-preserving gastrectomy (PPG) is a function-preserving surgery; however, long-term retention of food in the residual stomach is a frequent complication during the early postoperative period. We reported that gastric stasis after PPG was attributable to the delayed recovery of gastric phase III, in which pyloric relaxation accompanied a contraction of the gastric body. The objective of the present study is to determine whether erythromycin can induce phase III with pyloric relaxation after PPG.

METHODS

We studied gastrointestinal motility in dogs after PPG by using strain gauge force transducer. After randomized administration of either erythromycin or saline, interdigestive gastropyloroduodenal motility was recorded.

RESULTS

Erythromycin induced phase III with pyloric relaxation in the early postoperative period. Pyloric relaxation accompanied a contraction of the gastric body. Compared with the saline group (body: 87.2 +/- 16.7 mmHg x min, antrum: 69.7 +/- 13.7 mmHg x min, pylorus: 91.7 +/- 22.1 mmHg x min), the erythromycin group showed significantly increased gastropyloric motility indexes (body: 506.2 +/- 33.5 mmHg x min, antrum: 430.9 +/- 53.7 mmHg x min, pylorus: 589.5 +/- 59.5 mmHg x min).

CONCLUSIONS

Erythromycin can induce phase III, in which pyloric relaxation accompanied a contraction of the gastric body in the early postoperative period after PPG. Erythromycin might be used as a prokinetic agent for the treatment of early gastric stasis after PPG.