Effects of mitemcinal (GM-611), an orally active erythromycin-derived prokinetic agent, on delayed gastric emptying and postprandial glucose in a new minipig model of diabetes

Mild diabetes: long-term effects on gastric motility evaluated in rats

Moderate hyperglycaemic levels seem to be related to abnormal gastric motility in diabetes mellitus. However, experimental models designed to evaluate the relationship between motility and diabetes over time are not yet well established. Our objective was to investigate the long-term effects of mild diabetes on gastric motility in rats. Newborn male rats received streptozotocin (mild diabetes groups - MD) or vehicle (control groups - C), and both groups were evaluated after 3 (C3 and MD3) and 6 months (C6 and MD6) postinduction. Mild diabetic animals (MD3 and MD6) showed moderately elevated blood glucose and decreased insulin levels compared with control (C3 and C6). Insulin secretion was enhanced in MD6 compared with MD3, most likely due to partial β-cell regeneration indicated by HOMA-β. In HOMA-IR, it was noticed that MD6 animals had impaired insulin response compared with MD3. Gastric emptying was faster, amplitude of contraction was stronger in MD6 compared with MD3, and in both groups, the differences were significant when compared with control animals. A significant abnormal rhythmic index was calculated for the mild diabetic groups, despite unchanged mean frequency of contraction. In conclusion, despite increased insulin levels over time, constant levels of moderate hyperglycaemia are also related to abnormal gastric motility and impairment of gastric function.

Drug-drug interactions in pharmacologic management of gastroparesis

BACKGROUND

Gastroparesis is a disorder characterized by delayed gastric emptying due to chronic abnormal gastric motility. The treatment of the disease often entails the co-administration of several classes of pharmacological agents. These agents may be metabolized via the same pathway. Inhibition or induction of a shared metabolic pathway leads to change in the systemic levels of prescribed drugs, possibly leading to undesired clinical outcomes.

PURPOSE

This review discusses different pharmacological treatment for gastroparesis patients and describes the potential for drug-drug interactions (DDIs) in some of the combinations that are currently used. Prokinetic agents such as metoclopramide and domperidone are the cornerstone in treatment of gastroparesis. Antiemetic agents such as promethazine and ondansetron are frequently administered to gastroparesis patients to reduce nausea and vomiting. Gastroparesis is prevalent in diabetic patients and therefore antidiabetic agents are also prescribed. Many of these co-administered drugs are metabolized via common drug metabolizing enzymes and this can trigger potential DDIs. The scientific literature was reviewed from the years 1975-2014 for original research articles and reviews that evaluated DDIs in gastroparesis. Many commonly prescribed combinations were predicted to cause potential DDIs in gastroparesis patients. This review will help inform about potential hazardous combinations. This information will hopefully lead to less adverse effects and more successful gastroparesis management.

Establishment and evaluation of animal models of diabetic gastroparesis

The incidence of diabetic gastrointestinal disease, one of the most common complication of diabetes, is growing in recent years. Establishing an adequate animal model of diabetic gastrointestinal disease could effectively lay a solid foundation for the exploration of its mechanism and treatment. The rate of gastric emptying in diabetic gastrointestinal disease varies from acceleration to deceleration in different stages, and there is a lack of objective indicators to evaluate it. The establishment and evaluation of animals with diabetic gastrointestinal disease is still in the exploration stage. In this paper we summarize the establishment and evaluation of animal models of diabetic gastrointestinal disease. We compare the advantages and disadvantages of these animal models, in order to provide a reference for further study and treatment of this disease.

Duodenal application of Li+ in a submaximal therapeutic dose inhibits exocrine pancreatic secretion and modulates gastro-duodenal myoelectrical activity in a conscious pig model

This study tested whether duodenal application of lithium inhibits gastroduodenal motility, and whether it suppresses secretion from the exocrine pancreas. Five suckling pigs, 16–18 days old, were surgically fitted with 3 serosal electrodes on the wall of the gastric antrum and the duodenum for electromyography of smooth muscles, and with a pancreatic duct catheter and a duodenal T-cannula for collection and re-entrant flow of pancreatic juice. After the recovery period, on alternative days, each animal was tested once with an intraduodenal infusion of Li+ (100 mmol·L–1C3H5LiO3,10 mL·kg−1·h−1) for 1 h, and once with an intraduodenal infusion of NaCl (154 mM, 10 ml·kg−1·h−1), also for 1 h, with the first treatment, i.e., Li+ or NaCl, randomly assigned. Individual pigs served as their own controls, with data recorded prior to a treatment being used as the baseline. Li+ increased the duration of quiescence (P < 0.05) and activity phase (P < 0.05) in the antrum, thus increasing (P < 0.05) the duration of antral myoelectrical cycles. Li+ shortened (P < 0.05) phase I, but it did not affect phase II or phase III or the MMC in the duodenum. Li+ inhibited pancreatic juice outflow as well as pancreatic enzyme and bicarbonate output (P < 0.05 for all pancreatic parameters).

Management of reflux-related symptoms

Gastro-oesophageal reflux disease develops when the reflux of gastric contents into the oesophagus results in troublesome symptoms and/or complications [1]. Refluxate contains predominantly acid which causes tissue injury at oesophageal and extra-oesophageal sites. It is one of the commonest gastrointestinal diagnosis worlds over. It is associated with chronic symptoms, reduced QOL, significant cost and serious complications. Goals of therapy are to provide symptom relief, heal oesophagitis and prevent long-term complications. Therapeutic measures are directed at reducing the noxiousness of the refluxate; reducing the gastro-oesophageal reflux; enhancing clearance; protecting the mucosa; reducing the mucosal sensitivity and improving healing. Acid suppression with proton pump inhibitors remains the cornerstone of therapy. Recent studies have resulted in better understanding of disease and relative efficacies of various strategies. This has paved way for a better evidence based approach. The therapy however needs to be individualized depending upon the clinical profile, disease severity, the dominant pathophysiological mechanism, cost, availability and individual preferences.

Novel pharmaceutical approaches to reflux disease

Acid suppression, with proton pump inhibitors (PPI), is the mainstay of therapy for reflux disease; despite this, symptoms and injury persist in many patients. Novel approaches have focused on (1) augmenting acid suppression with reformulated current PPIs, new PPIs or new acid pump blockers and (2) preventing reflux with reflux inhibitors. Other strategies to reduce reflux, improve gastric emptying or esophageal clearance, protect the mucosa, or reduce esophageal sensitivity are under investigation alone or in combination with PPIs; however, novel approaches face significant challenges. The safety and efficacy of current PPIs hamper demonstration of clinical superiority for new acid suppressants, and the multifactorial etiology of reflux disease means that monotherapy using a non-acid suppressant is unlikely to match PPI therapy while combination therapy will be superior only if susceptible patients can be identified reliably. Advances will come, not from a 'one size fits all' approach but rather from novel pharmaceuticals allied to novel investigations to permit targeted, personalized reflux therapy.

Acute effects of different glycemic index diets on serum motilin, orexin and neuropeptide Y concentrations in healthy individuals

AIM

To determine whether different glycemic index (GI) diets have different effects on the acute secretion of motilin, orexin and neuropeptide Y (NPY), regulators of food intake, energy homeostasis and glucose metabolism.

METHODS

Fifty healthy volunteers were randomly assigned to two groups and were fed an isocaloric breakfast (464 kcal) containing high GI (HGI; GI=90) or low GI (LGI; GI=47) components. Serum motilin, orexin, and NPY concentrations were measured before (0 h) and 2h after the meal.

RESULTS

The concentrations of motilin, orexin-A, NPY, C-peptide, and blood glucose at 0 h were similar in both groups of subjects. However, 2 h after breakfast, the serum motilin, NPY, C-peptide, and blood glucose concentrations were increased and orexin-A concentrations were decreased in both groups. The percentage changes from 0 to 2 h [(2-h value-0-h value)/baseline×100)] in motilin (27.72±2.46% vs. 20.95±2.06%, p=0.04) and orexin-A (9.15±2.06% vs. 3.49±1.67%, p=0.038) concentrations were significantly higher in the LGI group than in the HGI group. By contrast, the percentage changes in NPY (53.7±9.73% vs. 28.1±5.2%, p=0.026) and blood glucose (12.3±3.78% vs. 1.77±2.52%, p=0.025) concentrations were significantly greater in the HGI group than in the LGI group. Although C-peptide concentrations increased significantly after breakfast in both groups, the magnitude of the increase was similar (132.69±25.15% vs. 139.98±27.29%, p=0.845). Motilin and NPY concentrations were moderately positive correlated (r=0.410, p=0.042), while orexin-A and NPY concentrations were negatively correlated (r=-0.429, p=0.033) at 2h in the LGI group.

CONCLUSIONS

A breakfast with a LGI reduced the secretion of orexin-A but significantly stimulated motilin secretion, without marked effects on the secretion of NPY. Therefore, consumption of a LGI diet may help to regulate food intake and energy expenditure in healthy individuals based on the changes in these hormones.

Dyspepsia: organic versus functional

Dyspepsia is the medical term for difficult digestion. It consists of various symptoms in the upper abdomen, such as fullness, discomfort, early satiation, bloating, heartburn, belching, nausea, vomiting, or pain. The prevalence of dyspepsia in the western world is approximately 20% to 25%. Dyspepsia can be divided into 2 main categories: "organic" and "functional dyspepsia" (FD). Organic causes of dyspepsia are peptic ulcer, gastroesophageal reflux disease, gastric or esophageal cancer, pancreatic or biliary disorders, intolerance to food or drugs, and other infectious or systemic diseases. Pathophysiological mechanisms underlying FD are delayed gastric emptying, impaired gastric accommodation to a meal, hypersensitivity to gastric distension, altered duodenal sensitivity to lipids or acids, altered antroduodenojenunal motility and gastric electrical rhythm, unsuppressed postprandial phasic contractility in the proximal stomach, and autonomic nervous system-central nervous system dysregulation. Pathogenetic factors in FD are genetic predisposition, infection from Helicobacter pylori or other organisms, inflammation, and psychosocial factors. Diagnostic evaluation of dyspepsia includes upper gastrointestinal endoscopy, abdominal ultrasonography, gastric emptying testing (scintigraphy, breath test, ultrasonography, or magnetic resonance imaging), and gastric accommodation evaluation (magnetic resonance imaging, ultrasound, single-photon emission computed tomography, and barostat). Antroduodenal manometry can be used for the assessment of the myoelectrical activity of the stomach, whereas sensory function can be evaluated with the barostat, tensostat, and satiety test. Management of FD includes general measures, acid-suppressive drugs, eradication of H. pylori, prokinetic agents, fundus-relaxing drugs, antidepressants, and psychological interventions. This review presents an update on the diagnosis of patients presenting with dyspepsia, with an emphasis on the pathophysiological and pathogenetic mechanisms of FD and the differential diagnosis with organic causes of dyspepsia. The management of uninvestigated and FD, as well as the established and new pharmaceutical agents, is also discussed.

Novel canine models of obese prediabetes and mild type 2 diabetes

Human type 2 diabetes mellitus (T2DM) is often characterized by obesity-associated insulin resistance (IR) and beta-cell function deficiency. Development of relevant large animal models to study T2DM is important and timely, because most existing models have dramatic reductions in pancreatic function and no associated obesity and IR, features that resemble more T1DM than T2DM. Our goal was to create a canine model of T2DM in which obesity-associated IR occurs first, followed by moderate reduction in beta-cell function, leading to mild diabetes or impaired glucose tolerance. Lean dogs (n = 12) received a high-fat diet that increased visceral (52%, P < 0.001) and subcutaneous (130%, P < 0.001) fat and resulted in a 31% reduction in insulin sensitivity (S(I)) (5.8 +/- 0.7 x 10(-4) to 4.1 +/- 0.5 x 10(-4) microU x ml(-1) x min(-1), P < 0.05). Animals then received a single low dose of streptozotocin (STZ; range 30-15 mg/kg). The decrease in beta-cell function was dose dependent and resulted in three diabetes models: 1) frank hyperglycemia (high STZ dose); 2) mild T2DM with normal or impaired fasting glucose (FG), 2-h glucose >200 mg/dl during OGTT and 77-93% AIR(g) reduction (intermediate dose); and 3) prediabetes with normal FG, normal 2-h glucose during OGTT and 17-74% AIR(g) reduction (low dose). Twelve weeks after STZ, animals without frank diabetes had 58% more body fat, decreased beta-cell function (17-93%), and 40% lower S(I). We conclude that high-fat feeding and variable-dose STZ in dog result in stable models of obesity, insulin resistance, and 1) overt diabetes, 2) mild T2DM, or 3) impaired glucose tolerance. These models open new avenues for studying the mechanism of compensatory changes that occur in T2DM and for evaluating new therapeutic strategies to prevent progression or to treat overt diabetes.

Gastric motor and sensory function

PURPOSE OF REVIEW

Abnormalities of gastric sensory and motor function are considered key players in the pathogenesis of upper gastrointestinal symptoms in functional dyspepsia and in gastroparesis. This review summarizes recent progress in our understanding of gastric sensory and motor function in health and in disease.

RECENT FINDINGS

Although assessment of gastric emptying rate is often used in the clinical work-up of patients with functional dyspepsia or gastroparesis, the correlation with symptoms is generally poor. Central processing, related to psychosocial dysfunction, is increasingly implicated in the pathogensis of gastric hypersensitivity. Meal challenge test and in fact even simple ingestion of a meal induce increased symptom occurrence in functional dyspepsia. Impaired motor function in critically ill patients is increasingly being studied and recognized as a prognostically relevant factor. Studies have reported on pharmacological approaches as well as electrical stimulation in the treatment of gastric sensorimotor dysfunction.

SUMMARY

Progress in our understanding of the normal and abnormal gastric sensory and motor function may lead to new or improved treatment modalities. Areas of recent advances are the role of the central nervous system in visceral hypersensitivity, motor abnormalities of the stomach in critically ill patients and the exploration of novel pharmacotherapeutic approaches.

Motilides: a long and winding road: lessons from mitemcinal (GM-611) on diabetic gastroparesis

Mitemcinal (GM-611) is a macrolide motilin receptor agonist with acid-resistance and without antibiotic activity. Since ABT-229 (a first generation of motilin receptor agonist) had failed to demonstrate symptomatic relief in functional dyspepsia and diabetic gastroparesis, there is a controversy for which of prokinetics or relaxants is clinically beneficial. Currently, oral mitemcinal has been focused on diabetic gastroparesis under clinical development. It showed to accelerate gastric-emptying in diabetic animals and in patients with gastroparesis. The latest double-blind, placebo-controlled study demonstrated to be effective at improving diabetes-related gastroparesis symptoms. A sub-group analysis, which included patients with BMI < 35 kg/m2 and hemoglobin A1c < 10%, there were significantly more symptomatic relieves in the 10 mg mitemcinal group than in the placebo group. The frequency of adverse events did not differ between groups. Mitemcinal shows promise in the subset of patients who should be confirmed in future studies.

Erythromycin establishes early oral feeding in neonates operated for congenital intestinal atresias

PURPOSE

The recovery of gastrointestinal function following surgery for congenital intestinal atresias can be prolonged and may increase morbidity and hospital stay. This study was conducted to investigate the prokinetic effect of erythromycin in neonates undergoing surgery for small bowel atresias.

METHODS

A randomized-controlled trial was conducted at the Departments of Paediatrics and Paediatric Surgery, Military Hospital, Rawalpindi, Pakistan, from January to December 2007 to study the prokinetic effect of erythromycin (3 mg/kg per dose 4 times daily). Thirty consecutive neonates undergoing primary anastomosis for congenital small bowel atresias were randomly divided into two groups: group I (erythromycin) and group II (control). The groups were similar in terms of gestational age, sex, mode of delivery, birth weight and types of atresias. Postoperative recovery of intestinal functions was measured as time taken to achieve full enteral feed (150 ml/kg per 24 h), duration of total parenteral nutrition (TPN) and hospital stay.

RESULTS

Neonates receiving oral erythromycin achieved full enteral feeding early (13.07 vs. 16.13 days) required TPN for shorter duration (10.53 vs. 13.73 days) and their hospital stay was less (16.2 vs. 18.0 days) as compared to the neonates in the control group who did not receive any erythromycin. The differences were statistically significant.

CONCLUSION

The administration of oral erythromycin following primary anastomosis for small intestinal atresias results in early recovery of intestinal function, fewer days on TPN and a trend for shorter hospital stay.

Treatment of refractory gastroparesis: gastric and jejunal tubes, botox, gastric electrical stimulation, and surgery

Refractory gastroparesis is a challenging disorder for gastroenterologists, internists, surgeons, and all health care professionals involved in the care of these patients. It should be managed by a stepwise algorithm beginning with dietary modifications, then prokinetic and antiemetic medications, measures to control pain and address psychological issues, and endoscopic or surgical options in selected patients, including placement of feeding jejunostomy tubes.