Effect of the 5-HT3 receptor antagonist, ondansetron, on gastric size in dyspeptic patients with impaired gastric accommodation

Efficacy and Safety of Drugs for Gastroparesis: Systematic Review and Network Meta-analysis

BACKGROUND & AIMS

Although there have been multiple drugs tested in gastroparesis, their relative efficacy and safety are unknown. We evaluated this in a network meta-analysis of randomized controlled trials (RCTs).

METHODS

We searched the literature to September 7, 2022. We judged the efficacy of drugs based on global symptoms of gastroparesis; individual symptoms, including nausea, vomiting, abdominal pain, bloating, or fullness; and safety according to total adverse events and adverse events leading to withdrawal. We extracted data as intention-to-treat analyses, assuming dropouts to be treatment failures and reporting pooled relative risks (RRs) of not improving with 95% confidence intervals (CIs), ranking drugs according to P-score.

RESULTS

We identified 29 RCTs (3772 patients). Based on global symptoms, clebopride ranked first for efficacy (RR, 0.30; 95% CI, 0.16-0.57; P-score = .99) followed by domperidone (RR, 0.68; 95% CI, 0.48-0.98; P-score = .76). No other drug was superior to placebo. Only 2 drug classes were efficacious: in rank order, oral dopamine antagonists (RR, 0.58; 95% CI, 0.44-0.77; P-score = .96) and tachykinin-1 antagonists (RR, 0.69; 95% CI, 0.52-0.93; P-score = .83). For individual symptoms, oral metoclopramide ranked first for nausea (RR 0.46; 95% CI, 0.21-1.00; P-score = .95), fullness (RR 0.67; 95% CI, 0.35-1.28; P-score = .86), and bloating (RR 0.53; 95% CI, 0.30-0.93; P-score = .97), based on only 1 small trial. Only prucalopride was more likely to be associated with adverse events than placebo.

CONCLUSIONS

In a network meta-analysis, oral dopamine antagonists and tachykinin-1 antagonists were more efficacious than placebo for gastroparesis, but confidence in the evidence was low to moderate for most comparisons. There is an unmet need for efficacious therapies for gastroparesis.

Gastrointestinal hormones and regulation of gastric emptying

PURPOSE OF REVIEW

In this review, we evaluate recent findings related to the association between gastrointestinal hormones and regulation of gastric emptying.

RECENT FINDINGS

Motilin and ghrelin, which act during fasting, promote gastric motility, whereas most of the hormones secreted after a meal inhibit gastric motility. Serotonin has different progastric or antigastric motility effects depending on the receptor subtype. Serotonin receptor agonists have been used clinically to treat dyspepsia symptoms but other hormone receptor agonists or antagonists are still under development. Glucagon-like peptide 1 agonists, which have gastric motility and appetite-suppressing effects are used as a treatment for obesity and diabetes.

SUMMARY

Gastrointestinal hormones play an important role in the regulation of gastric motility. Various drugs have been developed to treat delayed gastric emptying by targeting gastrointestinal hormones or their receptors but few have been commercialized.

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

BACKGROUND

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

PURPOSE

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

From Harmful Treatment to Secondary Gain: Adverse Event Reporting in Dyspepsia and Gastroparesis

INTRODUCTION

Medical management of gastroparesis and functional dyspepsia remains difficult with several recent trials showing limited or no benefit. If treatment comes with only marginal improvements, concerns about adverse events become more relevant. We therefore examined the type and outcomes of side effects submitted to a public repository.

METHODS

We searched the Federal Adverse Event Reporting System for reports associated with the treatment of dyspepsia or gastroparesis. Demographic data, medications used and implicated, side effects, and outcomes were abstracted for the years 2004-2015.

RESULTS

Acid-suppressive agents and prokinetics were the most commonly listed medications with a stronger emphasis on prokinetics in gastroparesis. Submissions related to metoclopramide by far exceeded reports about other agents and mostly described tardive dyskinesia or other neurological concerns. They peaked around 2012, driven by submissions through legal workers. Most reports about metoclopramide described short-term use to prevent or treat nausea and vomiting. Concerns about acid-suppressive medications increased over time and spanned a wide spectrum of potential problems, including osteoporosis, worsening renal function, or cardiac events.

CONCLUSION

Despite biasing factors, such as pending legal action, the voluntary repository of adverse events provides insight into current medical practice and its associated risk. Knowing about common and uncommon, but potentially serious risks may enable patients and providers to decide on effective and safe management strategies.

Visceral hypersensitivity and electromechanical dysfunction as therapeutic targets in pediatric functional dyspepsia

Functional gastrointestinal disorders (FGID) are common clinical syndromes diagnosed in the absence of biochemical, structural, or metabolic abnormalities. They account for significant morbidity and health care expenditures and are identifiable across variable age, geography, and culture. Etiology of abdominal pain associated FGIDs, including functional dyspepsia (FD), remains incompletely understood, but growing evidence implicates the importance of visceral hypersensitivity and electromechanical dysfunction. This manuscript explores data supporting the role of visceral hypersensitivity and electromechanical dysfunction in FD, with focus on pediatric data when available, and provides a summary of potential therapeutic targets.

Safety and efficacy of cyproheptadine for treating dyspeptic symptoms in children

OBJECTIVE

To present our experience using cyproheptadine, a potent serotonin antagonist used to stimulate appetite, to treat dyspeptic symptoms in children.

STUDY DESIGN

This was a retrospective open-label study conducted to evaluate the safety and efficacy of cyproheptadine in children with refractory upper gastrointestinal symptoms (eg, nausea, early satiety, vomiting, retching after fundoplication, abdominal pain). Response was graded as resolution if symptoms resolved and medication was discontinued, as significant improvement if symptoms resolved with no further interventions, and as failure with any other outcome.

RESULTS

A total of 80 children (65% females) aged <12 years (mean age, 10 years) were included. Response to therapy was reported in 55% of patients. Multivariate analysis revealed better response in children and females (P = .04 and .03, respectively). No associations were found between response to therapy response and gastric emptying, antroduodenal manometry, functional dyspepsia, vomiting, and use of cyproheptadine as first therapy. Early vomiting (occurring within 1 hour after starting a meal) responded better than late vomiting (P = .03), and patients with retching after undergoing Nissen fundoplication had an 86% response rate. Twenty-four patients (30%) complained of side effects, all mild, including somnolence (16%), irritability and behavioral changes (6%), increased appetite and weight gain (5%), and abdominal pain (2.5%), but only 2 of these patients discontinued therapy. Multivariate analysis demonstrated an association between side effects and lack of response to therapy (P = .04), but no associations with age and sex.

CONCLUSION

Cyproheptadine is safe and effective for treating dyspeptic symptoms in children, particularly in young children and those with early vomiting and retching after fundoplication.

Effect of mianserin on gastric sensorimotor function and gastric emptying: a randomized, placebo-controlled, double-blind, crossover study in healthy volunteers

BACKGROUND

Antidepressants such as mianserin can improve symptoms in some functional dyspeptic patients but their mechanism of action remains unclear. We aimed to assess the effects of mianserin on gastric sensorimotor function in man.

METHODS

In this randomized, placebo-controlled, double-blind, crossover study 12 healthy subjects (six men) underwent a gastric barostat study and a gastric emptying breath test after 7 days pretreatment with placebo or mianserin (20 mg; p.o.). Graded isobaric and isovolumetric distentions were performed to determine gastric compliance and sensitivity. Subsequently, intrabag pressure was held constant and the volume increase after administration of a liquid meal (200 mL; 300 kcal) was studied. Breath was sampled before and after ingestion of a test meal and half-emptying times for solids and liquids were determined from the breath samples. Mianserin was compared to placebo using t-tests and mixed model analysis (mean ± SD).

KEY RESULTS

Mianserin did not affect pressures or volumes needed to induce first perception or discomfort. During isovolumetric distensions compliance was decreased after mianserin treatment (1.8 ± 0.4 vs 2.0 ± 0.3 mmHg 100 mL(-1); P < 0.05). Premeal volumes were comparable in both treatment arms (221 ± 99 vs 220 ± 88 mL), but meal-induced relaxation during the first 30 min was significantly inhibited after mianserin treatment (F(6,40) = 2.58, P < 0.05). Mianserin did not affect either solid or liquid gastric emptying.

CONCLUSIONS & INFERENCES

Mianserin does not alter gastric emptying rate or sensitivity to gastric distension, but inhibits gastric accommodation to a meal in its early phase. These observations provide no explanation for the effects of mianserin in functional dyspeptic patients.

Influence of the 5-HT3 receptor antagonist ondansetron on gastric sensorimotor function and nutrient tolerance in healthy volunteers

BACKGROUND

Serotonin is believed to be involved in the regulation of the gastric accommodation reflex in man however which receptor subtype(s) are involved remains to be elucidated.

METHODS

Eleven healthy subjects (nine men, age 19-30) underwent a gastric barostat and a drinking test after treatment with either placebo or ondansetron (8 mg intravenously). During the barostat protocol an intragastric flaccid bag was stepwise distended (2 mmHg increments 2 min) to determine gastric compliance and sensitivity to distention. Subsequently, the pressure level was set at intra-abdominal pressure +2 mmHg while volume was followed before and after administration of a liquid meal (200 mL; 300 kcal). During the drink test volunteers drank at a rate of 15 mL min(-1) until maximal satiation. Results (mean ± SEM) were compared using t-tests and mixed model analysis.

KEY RESULTS

Gastric compliance was not significantly altered by ondansetron (51.5 ± 5.6 vs 49.2 ± 5.2 mL mmHg(-1)), neither were the pressure thresholds for first perception or discomfort. Ondansetron treatment did not affect basal gastric tone (173 ± 14 vs 156 ± 12 mL), neither did it affect the amplitude of the meal-induced relaxation (160 ± 52 vs 131 ± 43 mL) or the maximum volume increase after the meal (264 ± 54 mL vs 234 ± 51 mL). During the drinking test the amount of liquid meal ingested at maximum satiation was significantly increased by ondansetron (784 ± 74 vs 907 ± 64 mL, P < 0.05).

CONCLUSIONS & INFERENCES

These data suggest that 5-HT acting at 5-HT(3) receptors is not involved in the control of gastric sensorimotor function, but contributes to the regulation of hunger and satiation in man.

The effects of acute citalopram dosing on gastric motor function and nutrient tolerance in healthy volunteers

BACKGROUND

It is unclear whether endogenous serotonin release is involved in the regulation of gastric motility and food intake.

AIM

To study the effect of acute administration of the selective serotonin reuptake inhibitor citalopram on gastric motor function in man.

METHODS

Nineteen healthy volunteers underwent a gastric barostat, gastric emptying and/or a drinking test after dosing with either placebo or citalopram (20 mg intravenously). In the barostat protocol, a flaccid bag was introduced in the stomach and inflated at intra-abdominal pressure +2 mmHg, volume was recorded before and after administration of a liquid meal (300 kcal). Gastric emptying for solids and liquids was simultaneously assessed using the ¹⁴C-octanoic acid/¹³C-glycine breath test. During the drink test, volunteers drank at a rate of 15 mL/min until maximal satiation. Citalopram was compared with placebo using t-tests and mixed model analysis.

RESULTS

Citalopram induced a significant preprandial gastric relaxation (volume increase of 154 ± 55 mL vs. -38 ± 33 mL after placebo dosing; P < 0.05), whereas the postprandial volume increase was significantly decreased after citalopram treatment (F₁₂.₈₀ = 4.78, P < 0.0001; maximum volume increase was 304 ± 40 vs. 201 ± 54 mL after placebo and citalopram treatment respectively). Citalopram enhanced solid (123 ± 17 vs. 77 ± 6 min, P < 0.05) but not liquid emptying (62 ± 6 vs. 57 ± 4 min). Satiation scores during the drink test were lower after citalopram (F₁₉.₁₅₃ = 2.02, P = 0.01; volunteers drank 998 ± 129 vs. 765 ± 79 mL after citalopram and placebo treatment respectively).

CONCLUSION

The observed effects indicate a role for serotonin in the control of gastric motility and food intake.