Should cisapride be avoided in patients with diabetic gastroparesis?

Cisapride induced hypoglycemia via the KCNH6 potassium channel

Mutations in KCNH6 has been proved to cause hypoinsulinemia and diabetes in human and mice. Cisapride is a stomach-intestinal motility drug used to treat gastrointestinal dysfunction. Cisapride has been reported to be a potential inhibitor of the KCNH family, but it remained unclear whether cisapride inhibited KCNH6. Here, we discovered the role of cisapride on glucose metabolism, focusing on the KCNH6 potassium channel protein. Cisapride reduced blood glucose level and increased serum insulin secretion in wild-type (WT) mice fed standard normal chow/a high-fat diet or in db/db mice, especially when combined with tolbutamide. This effect was much stronger after 4 weeks of intraperitoneal injection. Whole-cell patch-clamp showed that cisapride inhibited KCNH6 currents in transfected HEK293 cells in a concentration-dependent manner. Cisapride induced an increased insulin secretion through the disruption of intracellular calcium homeostasis in a rat pancreatic β-cell line, INS-1E. Further experiments revealed that cisapride did not decrease blood glucose or increase serum insulin in KCNH6 β-cell knockout (Kcnh6-β-KO) mice when compared with WT mice. Cisapride also ameliorated glucose-stimulated insulin secretion (GSIS) in response to high glucose in WT but not Kcnh6-β-KO mice. Thus, our data reveal a novel way for the effect of KCNH6 in cisapride-induced hypoglycemia.

Diabetic Gastroparesis: Principles and Current Trends in Management

This article is a comprehensive review of diabetic gastroparesis, defined as delayed or disordered gastric emptying, including basic principles and current trends in management. This review includes sections on anatomy and physiology, diagnosis and differential diagnosis as well as management and current guidelines for treatment of diabetic gastroparesis. Diabetic gastroparesis (DGp) is a component of autonomic neuropathy resulting from long-standing poorly controlled type 1 and type 2 diabetes. The diagnostic workup of DGp first excludes obstruction and other causes including medications that may mimic delayed/disordered gastric emptying. Targeting nutrition, hydration, symptomatic relief and glycemic control are mainstays of treatment for DGp. Additionally, optimal treatment of DGp includes good glycemic management, often involving customizing insulin delivery using basal-bolus insulin and technology, including sensor-augmented pumps and continuous glucose monitoring systems. Prokinetic medications may be helpful in DGp symptoms, although only limited number of medications is currently available in the USA. Selected medication-refractory patients with DGp may benefit from gastric neuromodulation, and some from surgical interventions including pyloric therapies that can also be done endoscopically. As is true of any of the diabetic complications, prevention of DGp by early and optimal glycemic control is more cost-effective.Funding: Hansa Medcell, India.

Systematic review: cardiovascular safety profile of 5-HT(4) agonists developed for gastrointestinal disorders

BACKGROUND

The nonselective 5-HT(4) receptor agonists, cisapride and tegaserod have been associated with cardiovascular adverse events (AEs).

AIM

To perform a systematic review of the safety profile, particularly cardiovascular, of 5-HT(4) agonists developed for gastrointestinal disorders, and a nonsystematic summary of their pharmacology and clinical efficacy.

METHODS

Articles reporting data on cisapride, clebopride, prucalopride, mosapride, renzapride, tegaserod, TD-5108 (velusetrag) and ATI-7505 (naronapride) were identified through a systematic search of the Cochrane Library, Medline, Embase and Toxfile. Abstracts from UEGW 2006-2008 and DDW 2008-2010 were searched for these drug names, and pharmaceutical companies approached to provide unpublished data.

RESULTS

Retrieved articles on pharmacokinetics, human pharmacodynamics and clinical data with these 5-HT(4) agonists, are reviewed and summarised nonsystematically. Articles relating to cardiac safety and tolerability of these agents, including any relevant case reports, are reported systematically. Two nonselective 5-HT(4) agonists had reports of cardiovascular AEs: cisapride (QT prolongation) and tegaserod (ischaemia). Interactions with, respectively, the hERG cardiac potassium channel and 5-HT(1) receptor subtypes have been suggested to account for these effects. No cardiovascular safety concerns were reported for the newer, selective 5-HT(4) agonists prucalopride, velusetrag, naronapride, or for nonselective 5-HT(4) agonists with no hERG or 5-HT(1) affinity (renzapride, clebopride, mosapride).

CONCLUSIONS

5-HT(4) agonists for GI disorders differ in chemical structure and selectivity for 5-HT(4) receptors. Selectivity for 5-HT(4) over non-5-HT(4) receptors may influence the agent's safety and overall risk-benefit profile. Based on available evidence, highly selective 5-HT(4) agonists may offer improved safety to treat patients with impaired GI motility.

Effect of itopride on gastric emptying in longstanding diabetes mellitus

Delayed gastric emptying (GE) occurs in 30-50% of patients with longstanding type 1 or 2 diabetes, and represents a major cause of morbidity. Current therapeutic options are limited. We aimed at evaluating the effects of itopride on GE in patients with longstanding diabetes. Twenty-five patients (20 type 1, 5 type 2; 10 males, 15 females; mean age 45.2 +/- 2.7 years; body mass index 27.5 +/- 0.9 kg m(-2); duration of diabetes 20.2 +/- 2.4 years) were enrolled in a double-blind, placebo-controlled, randomized, crossover trial. Subjects received both itopride (200 mg) and placebo t.i.d. for 7 days, with a washout of 7-14 days. GE (scintigraphy), blood glucose (glucometer) and upper gastrointestinal (GI) symptoms (questionnaire) were measured following each treatment period. The test meal comprised 100 g ground beef (99mTc-sulphur colloid) and 150 mL of 10% dextrose [67Ga-ethylenediaminetetraacetic acid (EDTA)]. There was a slight trend for itopride to accelerate both solid (P = 0.09) and liquid (P = 0.09) GE. With itopride treatment, the emptying of both solids and liquids tended to be more accelerated, as the emptying with placebo was slower (solids: r = 0.39, P = 0.057; liquids: r = 0.44, P < 0.03). Twelve (48%) patients had delayed solid and/or liquid GE on placebo and in this group, itopride modestly accelerated liquid (P < 0.05), but not solid (P = 0.39), emptying. Itopride had no effect on mean blood glucose during the GE measurement (placebo: 9.8 +/- 0.6 mmol L(-1) vs itopride: 9.6 +/-0.6 mmol L(-1)), or GI symptoms (placebo: 1.4 +/- 0.4 vs itopride: 1.8 +/- 0.5). Itopride, in a dose of 200 mg t.i.d. for 7 days, tends to accelerate GE of liquids and solids in longstanding diabetes. The magnitude of this effect appears to be modest and possibly dependent on the rate of GE without itopride.

Gastroparesis: clinical update

Gastroparesis refers to chronically abnormal gastric motility characterized by symptoms suggestive of mechanical obstruction and delayed gastric emptying in the absence of mechanical obstruction. It may be idiopathic or attributable to neuropathic or myopathic abnormalities, such as diabetes mellitus, postvagotomy, postviral infection, and scleroderma. Dietary and behavioral modification, prokinetic drugs, and surgical interventions have been used in managing patients with gastroparesis. Although mild gastroparesis is usually well managed with these treatment options, severe gastroparesis may be very difficult to control and may require referral to a specialist center if symptoms are intractable despite pharmacological therapy and dietetic support. New advances in drug therapy, botulinum toxin injection, and gastric electrical stimulation techniques have been introduced and might provide new hope to patients with refractory gastroparesis. This article critically reviews the advances in the field from the perspective of the clinician.

Effect of the motilin agonist KC 11458 on gastric emptying in diabetic gastroparesis

BACKGROUND

KC 11458, a motilin agonist without antibiotic properties, accelerates gastric emptying in animals and healthy humans.

AIM

To evaluate the acute effects of KC 11458 on gastric emptying in diabetic gastroparesis.

METHODS

Twenty-nine patients (6 type 1 and 23 type 2) with gastroparesis underwent assessments of: (i) gastric emptying of a solid/liquid meal using scintigraphy, (ii) glycaemic control (blood glucose at 0, 30, 60, 90 and 120 min during the gastric emptying measurement) and (iii) upper gastrointestinal and 'meal-related' symptoms (questionnaire), at baseline and after treatment with KC 11458 in a dose of 8 mg t.d.s., or placebo for 8 days.

RESULTS

KC 11458 had no statistically significant or clinically relevant effect on gastric emptying of either the solid intragastric retention at 100 min (T100) (P = 0.87) or liquid 50% emptying time (T50) (P = 0.17) components of the meal. KC 11458 slightly worsened (P = 0.04) upper gastrointestinal symptoms when compared with placebo. The magnitude of the change in solid gastric emptying correlated with the change in the blood glucose concentration (r = 0.49; P < 0.05).

CONCLUSIONS

KC 11458, in a dose of 8 mg t.d.s. for 8 days, does not accelerate gastric emptying in patients with diabetic gastroparesis. The absence of efficacy may relate to an effect of hyperglycaemia.

Idiopathic and Diabetic Gastroparesis

The management of both diabetic and idiopathic gastroparesis often represents a substantial clinical challenge. In formulating recommendations for therapy, it should be recognized that these are based on less than optimal evidence; in particular, there are substantial deficiencies in current knowledge relating to the pathophysiology of gastroparesis, as well as the natural history of gastrointestinal symptoms, and the majority of pharmacologic trials have been short term and associated with methodologic limitations. Although the etiologic factors differ, the overall management principles are similar in the two conditions. Maintenance of adequate nutrition is pivotal, and parenteral nutrition may be required in severe cases associated with malnutrition. In patients with diabetes, rigorous attempts should be made to optimize glycemic control--hyperglycemia slows gastric emptying and may exacerbate symptoms and attenuate the effects of prokinetic drugs. Despite the relatively poor predictive value of symptoms, it is reasonable to suggest a trial of prokinetic therapy for about 4 weeks, rather than initially establishing the diagnosis by measurement of gastric emptying. However, it should be recognized that there is a substantial placebo response, a lack of evidence to support the cost effectiveness of such an approach, and that most patients will require prolonged therapy. In type 1 diabetic patients, prokinetic therapy may potentially benefit glycemic control, and this forms an additional rationale (albeit not established) for therapy. Some patients with diabetes and idiopathic gastroparesis with severe vomiting are unable to tolerate oral medication; in such cases subcutaneous metoclopramide may prove useful. Patients with intractable symptoms should be hospitalized and given intravenous erythromycin. The repertoire of prokinetic agents available in the United States is limited and includes metoclopramide, erythromycin, and cisapride (available by special program from its manufacturer); all of these drugs are associated with side effects. The use of metoclopramide may represent the first choice for chronic oral therapy, although it has been studied less comprehensively than cisapride. Combination therapy may be potentially more efficacious than the use of single agents. Dehydration and metabolic derangements should be corrected. The choice of chronic medical therapy should be individualized, taking factors such as age, presence of diabetes, concurrent medications, and comorbidities into account. In a small number of patients in whom medical treatment fails, surgery should be considered, and, if performed, done in a specialized center. A number of novel therapies, including gastric electrical stimulation, are currently being evaluated.

Gastric emptying in diabetes: clinical significance and treatment

The outcome of recent studies has led to redefinition of concepts relating to the prevalence, pathogenesis and clinical significance of disordered gastric emptying in patients with diabetes mellitus. The use of scintigraphic techniques has established that gastric emptying is abnormally slow in approx. 30-50% of outpatients with long-standing Type 1 or Type 2 diabetes, although the magnitude of this delay is modest in many cases. Upper gastrointestinal symptoms occur frequently and affect quality of life adversely in patients with diabetes, although the relationship between symptoms and the rate of gastric emptying is weak. Acute changes in blood glucose concentration affect both gastric motor function and upper gastrointestinal symptoms. Gastric emptying is slower during hyperglycaemia when compared with euglycaemia and accelerated during hypoglycaemia. The blood glucose concentration may influence the response to prokinetic drugs. Conversely, the rate of gastric emptying is a major determinant of post-prandial glycaemic excursions in healthy subjects, as well as in Type 1 and Type 2 patients. A number of therapies currently in development are designed to improve post-prandial glycaemic control by modulating the rate of delivery of nutrients to the small intestine.