Camilleri, Michael

Agonists targeting the receptors of incretin hormones, glucagon-like peptide-1 and glucose-dependent insulinotropic peptide, have been well established for the treatment of type 2 diabetes mellitus. There is increasing awareness that gastroenterologists and hepatologists should be treating obesity when patients present to their clinics. In addition, gastroenterologists and hepatologists should be aware of the effects of these classes of medications prescribed by other providers. Therefore, given the widespread use of incretin agonists for obesity treatment and weight loss, it is important to recognize their effects in the gastrointestinal tract, which could constitute significant benefits in weight loss and cardiometabolic benefits, but can be associated with adverse effects that constitute a potential barrier to their use, particularly at higher doses. Multiple studies reviewed in this article document the diverse effects of these drugs on the glucagon-like peptide-1 receptors that are widely expressed in the human body, including the nervous system modulating appetite, the gastrointestinal tract modifying gastric emptying, and lipid metabolism regulation leading to reduction in fat deposition. The objective of this review is to summarize the mechanism of action of incretin receptor agonists, their effects in the gastrointestinal tract, and implications in clinical practice, particularly in the practice of gastroenterology, endoscopy, and surgery.

Obesity is highly prevalent in hepatology clinics and has a significant impact on chronic liver disease and patient management. Hepatologists and gastroenterologists need to be actively engaged in the management of obesity. This review provides a detailed approach to this challenging comorbidity.

Objective Symptoms in gastroparesis (Gp) and functional dyspepsia (FD) overlap; using egg protein substitute to measure gastric emptying of solids (GES), ~40% of patients are reclassified from Gp to FD, and vice versa. Our aim was to assess inter-individual and intra-individual coefficients of variation (COV) in GES in symptomatic patients with Gp or FD with documented slow or normal GES, respectively. Design Scintigraphic GES (T1/2 and GE% at 2 and 4 hours) using a 320 kcal real egg meal (30% fat) was tested in the following: single measurements in 20 patients with diabetes mellitus (10 each type 1 and type 2); repeat GES to estimate COVintra measured: 3 days apart in 9 Gp, 4 weeks apart in 21 Gp and 18 with FD with normal GE assigned to placebo and in 70 patients at 94.3 weeks (median) apart. Results COVinter for GE% at 4 hours and GE T1/2 were respectively 14.2% and 23.5% in FD and 27.5% and 33% in Gp; COVintra for GE% at 4 hours and GE T1/2 up to 4 weeks apart were 23.4% and 37.9% in FD and 20.1% and 33% in Gp. GE% at 2 hours showed less consistent results. However, >85% retained original diagnosis as normal or delayed. From clinical GES to baseline research for Gp group, repeat GES (after treatment) showed the COVintra for GE% at 4 hours was 37.3% at median 94.3 weeks, with 26/70 changed diagnoses. Conclusion The 320 kcal (30% fat) GES scintigraphic test provides consistent diagnosis in >85% and should be the standard test for suspected gastric emptying disorders.

The objective of this article is to review the evidence of abnormal gastrointestinal (GI) tract motor functions in the context of disorders of gut–brain interaction (DGBI). These include abnormalities of oesophageal motility, gastric emptying, gastric accommodation, colonic transit, colonic motility, colonic volume and rectal evacuation. For each section regarding GI motor dysfunction, the article describes the preferred methods and the documented motor dysfunctions in DGBI based on those methods. The predominantly non-invasive measurements of gut motility as well as therapeutic interventions directed to abnormalities of motility suggest that such measurements are to be considered in patients with DGBI not responding to first-line approaches to behavioural or empirical dietary or pharmacological treatment.

Summary Background A subset of patients with chronic constipation has associated slow colonic transit and reduced faecal bile acid excretion. In addition to traditional approaches to treat chronic constipation, a novel therapeutic option is to increase the colonic concentration of intraluminal bile acids. This can be achieved through inhibition of the ileal bile acid transporter. Aim To evaluate the evidence for efficacy and safety of an ileal bile acid transport inhibitor in the treatment of chronic constipation Methods We reviewed published literature on elobixibat, based on a PubMed search. Results Elobixibat is a novel ileal bile acid transport inhibitor that has demonstrated efficacy in proof of concept studies in experimental animals as well as phase 1, 2 and 3 trials in humans. Phase 4 studies have now documented that the beneficial effects are related to increase in the secretory bile acids in the colon as measured by stool bile acid content. The studies documented efficacy in patients with severe constipation, which is often associated with slow colonic transit. These changes in bile acid composition were associated with minor differences in the faecal microbiota in patients treated with elobixibat compared to placebo. Elobixibat appears to be safe. The only adverse effects of note are associated with its pharmacological actions in patients with chronic constipation,namely the induction of diarrhoea and abdominal pain. Conclusion This new class of compound appears to be safe and efficacious in the treatment of chronic constipation.

LINKED CONTENTThis article is linked to Khanna & Camilleri and Tobi et al papers. To view these articles, visit https://doi.org/10.1111/apt.16143 and https://doi.org/10.1111/apt.16270

SummaryBackgroundGastroparesis is defined by delayed gastric emptying with associated symptoms in the absence of mechanical obstruction.AimTo evaluate pharmacokinetics and pharmacodynamics of felcisetrag, a highly selective 5‐HT4 receptor agonist, on total gut transit in patients with documented delayed gastric emptying of solids.MethodsSingle‐centre, placebo‐controlled study of 36 participants receiving placebo, 0.1mg, 0.3mg or 1.0mg of felcisetrag I.V. infusion, daily, for 3 days. At baseline, each participant completed a 4h, 99mTc‐egg meal (300 kcal, 30% fat) gastric emptying test. Following infusion (Day 2), gastric, small bowel and colonic transit of solids were measured over 48h (same meal plus 111In‐charcoal delivered in methacrylate‐coated capsule). Samples were collected for pharmacokinetics. The primary endpoint was gastric emptying T1/2. Statistical analysis used baseline parameters as covariates (ANCOVA).ResultsPatients (22 idiopathic, 14 diabetic gastroparesis) were randomised to felcisetrag (0.1 mg, n = 10; 0.3 mg, n = 9; 1.0 mg, n = 7) or placebo (n = 10). Compared to placebo, felcisetrag significantly accelerated gastric emptying T1/2, colonic filling at 6h, and 10% small bowel transit time (overall P < 0.01; all three doses individually Bonferroni corrected P < 0.05) for all three measurements. Ascending colon emptying (T1/2) was significantly accelerated (all doses), and colonic transit at 48 hours was accelerated with 0.1 mg and 0.3 mg felcisetrag compared to placebo. Pharmacokinetic results were dose proportional. Felcisetrag was well tolerated with no clinically significant findings from clinical laboratory, vital signs or ECG.ConclusionI.V. felcisetrag significantly accelerated gastric, small bowel and colonic transit in patients with gastroparesis, and should be further evaluated for short‐term treatment of gastric and intestinal motility disorders.ClinicalTrials.gov #NCT03281577

AbstractPurposeThe objectives of this review are to summarize the role of gastric motor functions in the development of satiation (defined broadly as postprandial fullness) and satiety (reduced appetite or postponing desire to eat after a meal) and their impact on weight change. The specific topics are the methods of measurement of gastric emptying and accommodation and their impact on food intake, satiation, and satiety. A second focus contrasts bariatric surgery to endoscopic gastroplasty that alter gastric emptying and incretin responses in markedly divergent manners.BackgroundThe hormone, GLP‐1, retards gastric emptying and increases gastric accommodation through vagally‐mediated effects. Indeed, these effects provide the basis for the association of altered gastric emptying in the appetite and weight loss responses to pharmacological interventions particularly by those acting on receptors of incretin agonists such as liraglutide and the dual agonists, tirzepatide and cotadutide, all of which retard gastric emptying. In fact, retardation of gastric emptying and gastrointestinal adverse effects have been shown to contribute in part to the weight loss in response to this class of pharmacological agents.SummaryThe motor functions of the stomach are relevant to postprandial fullness and to interventions aimed at weight loss in people with obesity.

AbstractPropulsion of contents in the gastrointestinal tract requires coordinated functions of the extrinsic nerves to the gut from the brain and spinal cord, as well as the neuromuscular apparatus within the gut. The latter includes excitatory and inhibitory neurons, pacemaker cells such as the interstitial cells of Cajal and fibroblast-like cells, and smooth muscle cells. Coordination between these extrinsic and enteric neurons results in propulsive functions which include peristaltic reflexes, migrating motor complexes in the small intestine which serve as the housekeeper propelling to the colon the residual content after digestion, and mass movements in the colon which lead to defecation.