Prokinetics in diabetic gastroparesis

Metoclopramide nasal spray for management of symptoms of acute and recurrent diabetic gastroparesis in adults

Introduction: Gastroparesis (GP) is characterized by delayed gastric emptying in the absence of mechanical obstruction. About 75% of GP patients are females. Diabetes and idiopathic are the two commonest etiologies of GP. Up to two-thirds of the GP patients do not have significant symptom responses to medical therapies, and there is a paucity of available oral prokinetic agents with only one medication approved by the U.S. Food and Drug Administration (FDA) for this indication. The oral and parenteral formulations of metoclopramide were FDA approved in 1979 to treat symptoms of acute and recurrent diabetic GP. Now, more than 40 years later, a nasal preparation of metoclopramide (Gimoti^TM) was approved in June 2020 for the same indication.Areas covered: PubMed search using the keywords 'nasal metoclopramide' and 'diabetic gastroparesis.' This article aims to provide a concise review of the pharmacology, clinical efficacy, and tolerability of nasal metoclopramide.Expert opinion: The nasal formulation can be systemically absorbed without relying on the passage through a poorly emptying stomach, thus assuring the delivery of a therapeutic dose of metoclopramide, even during episodes of vomiting. Hence, metoclopramide nasal spray has the potential to be used during an acute flare, potentially avoiding hospitalizations.

Chronic nausea and vomiting: evaluation and treatment

Nausea is an uneasy feeling in the stomach while vomiting refers to the forceful expulsion of gastric contents. Chronic nausea and vomiting represent a diverse array of disorders defined by 4 weeks or more of symptoms. Chronic nausea and vomiting result from a variety of pathophysiological processes, involving gastrointestinal and non-gastrointestinal causes. The prevalence of chronic nausea and vomiting is unclear, although the epidemiology of specific conditions, such as gastroparesis and cyclic vomiting syndrome, is better understood. The economic impact of chronic nausea and vomiting and effects on quality of life are substantial. The initial diagnostic evaluation involves distinguishing gastrointestinal causes of chronic nausea and vomiting (e.g., gastroparesis, cyclic vomiting syndrome) from non-gastrointestinal causes (e.g., medications, vestibular, and neurologic disorders). After excluding anatomic, mechanical and biochemical causes of chronic nausea and vomiting, gastrointestinal causes can be grouped into two broad categories based on the finding of delayed, or normal, gastric emptying. Non-gastrointestinal disorders can also cause chronic nausea and vomiting. As a validated treatment algorithm for chronic nausea and vomiting does not exist, treatment should be based on a thoughtful discussion of benefits, side effects, and costs. The objective of this monograph is to review the evaluation and treatment of patients with chronic nausea and vomiting, emphasizing common gastrointestinal causes.

Cardiotoxic Antiemetics Metoclopramide and Domperidone Block Cardiac Voltage-Gated Na+ Channels

BACKGROUND

Metoclopramide and domperidone are prokinetic and antiemetic substances often used in clinical practice. Although domperidone has a more favorable side effect profile and is considered the first-line agent, severe cardiac side effects were reported during the administration of both substances. Cardiac Na channels are common targets of therapeutics inducing cardiotoxicity. Therefore, the aim of this study was to investigate whether the differential cardiotoxicities of metoclopramide and domperidone correlate with the block of Na channels.

METHODS

Effects of metoclopramide and domperidone on the human α-subunit Nav1.5 expressed in human embryonic kidney 293 cells and on Na currents in neonatal rat cardiomyocytes were investigated by means of whole-cell patch clamp recordings.

RESULTS

Tonic block of resting Nav1.5 channels was more potent for domperidone (IC50 85 ± 25 μM; 95% confidence interval [CI], 36-134) compared with metoclopramide (IC50 458 ± 28 μM; 95% CI, 403-513). Both agents induced use-dependent block at 10 and 1 Hz, stabilized fast and slow inactivation, and delayed recovery from inactivation. However, metoclopramide induced considerably smaller effects compared with domperidone. Na currents in rat cardiomyocytes displayed tonic and use-dependent block by both substances, and in this system, domperidone (IC50 312 ± 15 μM; 95% CI, 22-602) and metoclopramide (IC50 250 ± 30 μM; 95% CI, 191-309) induced a similar degree of tonic block.

CONCLUSIONS

Our data demonstrate that the clinically relevant cardiotoxicity of domperidone and metoclopramide corresponds to a rather potent and local anesthetic-like inhibition of cardiac Na channels including Nav1.5. These data suggest that Nav1.5 might be a hitherto unrecognized molecular mechanism of some cardiovascular side effects, for example, malignant arrhythmias of prokinetic and antiemetic agents.

Prokinetics in gastroparesis

Prokinetic agents are medications that enhance coordinated gastrointestinal motility and transit of content in the gastrointestinal tract, mainly by amplifying and coordinating the gastrointestinal muscular contractions. In addition to dietary therapy, prokinetic therapy should be considered as a means to improve gastric emptying and symptoms of gastroparesis, balancing benefits and risks of treatment. In the United States, metoclopramide remains the first-line prokinetic therapy, because it is the only approved medication for gastroparesis. Newer agents are being developed for the management of gastroparesis. This article provides detailed information about prokinetic agents for the treatment of gastroparesis.

Domperidone-associated sudden cardiac death in the general population and implications for use in patients undergoing hemodialysis: a literature review

BACKGROUND

Domperidone, an effective prokinetic agent, is commonly used to manage symptoms of gastroparesis. Health regulatory agencies have issued warnings about an increased risk of sudden cardiac death associated with use of this drug.

OBJECTIVE

To evaluate the evidence for domperidone-associated sudden cardiac death and to determine whether this drug can be safely used for gastroparesis in patients undergoing dialysis.

DATA SOURCES

Two databases (MEDLINE [1965 to September 2014] and Embase [1980 to September 2014]) were searched using the Medical Subject Headings "domperidone", "sudden cardiac death", and "cardiac arrhythmia". The search was limited to studies conducted in humans and published in English. Advisories from health regulatory agencies (Health Canada, the European Medicines Agency, and the US Food and Drug Administration) were identified and reviewed.

STUDY SELECTION

Studies eligible for inclusion in this narrative review were randomized controlled trials and cohort, case-control, cross-sectional, and other epidemiological studies comparing use and non-use of domperidone for the outcome of sudden cardiac death in adults. Abstracts of eligible case reports and case series were also included.

DATA SYNTHESIS

Despite inconsistencies in their decisions, the various drug regulatory authorities have acknowledged the potential safety concern of increased risk of sudden cardiac death associated with domperidone. To date, no randomized controlled studies have shown an increased risk of this outcome secondary to domperidone use. Current regulatory recommendations and approval decisions are based on 2 large observational epidemiological studies that generated a signal of increased risk. The strengths and limitations of these studies were evaluated in detail. No direct evidence applicable to patients with end-stage renal disease was found. In vitro evidence suggests that the risk of sudden cardiac death is dose-related.

CONCLUSIONS

Given gaps in the literature, use of domperidone for patients undergoing dialysis should be assessed on a case-by-case basis. Extreme caution should be used for patients taking more than 30 mg/day of this drug.

Measurement of gastric emptying by radiopaque markers in patients with diabetes: correlation with scintigraphy and upper gastrointestinal symptoms

BACKGROUND

Scintigraphy, the gold standard to measure gastric emptying, is expensive and not widely available. Therefore, we compared emptying of radiopaque markers (ROM) from the stomach, by use of fluoroscopy, with scintigraphy in patients with insulin-treated diabetes.

METHODS

On the same day we measured gastric emptying of 20 ROM using fluoroscopy and scintigraphic emptying of a standard solid meal. The subjects also completed a validated gastrointestinal (GI) symptom questionnaire.

KEY RESULTS

We included 115 patients with insulin-treated diabetes (median age 53, range 21-69 years; 59 women). A moderately strong correlation was demonstrated between scintigraphic (% retained at 2 h) and ROM emptying (markers retained at 6 h) (r = 0.47; P < 0.0001). Eighty-three patients had delayed gastric emptying with scintigraphy, whereas only 29 patients had delayed emptying of ROM. Of the 29 patients with delayed emptying of ROM, 28 also had delayed scintigraphic emptying. The sensitivity and specificity of the ROM test was 34% and 97%, respectively. Significant correlations were only noted between scintigraphic gastric emptying and GI symptom severity, with the strongest correlations for fullness/early satiety (r = 0.34; P < 0.001) and nausea/vomiting (r = 0.30; P < 0.001).

CONCLUSIONS & INFERENCES

A gastric emptying test with ROM is a widely available screening method to detect delayed gastric emptying in patients with diabetes, where a positive result seems reliable. However, a normal ROM test does not exclude delayed gastric emptying, and if the clinical suspicion of gastroparesis remains, scintigraphy should be performed. Results from scintigraphy also correlate with GI symptom severity, which ROM test did not.