• Journal of Neurogastroenterology and Motility
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• v.24 no.4
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• pp.577-583
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• 2018

Background/Aims Potassium-competitive acid blockers are expected to be the next generation of drugs for the treatment of diseases caused by gastric acid. In 2015, vonoprazan fumarate, a novel potassium-competitive acid blocker, was approved by the Japanese health insurance system. Since its approval, patients refractory to vonoprazan can be encountered in clinical settings. We designed this study to clarify the pathophysiology of gastroesophageal reflux disease refractory to vonoprazan. Methods In this retrospective study, we involved patients who had refractory symptoms after administration of standard-dose proton pump inhibitors or vonoprazan and underwent diagnostic testing with esophageal high-resolution manometry and 24-hour multichannel intraluminal impedance and pH monitoring while using proton pump inhibitors or vonoprazan. Patients were diagnosed based on the Rome IV criteria for functional gastrointestinal disorders and diagnostic test results. Results Twenty-seven patients were analyzed during this study. Gastric pH ${\geq}4$ was sustained for a longer period of time, and the esophageal acid exposure time and number of acid reflux events were shorter in the vonoprazan group than in the proton pump inhibitor group. The percentage of patients diagnosed with acidic gastroesophageal reflux disease in the vonoprazan group was lower than that in the proton pump inhibitor group. Conclusions Intra-gastric pH and acid reflux were strongly suppressed by 20-mg vonoprazan. When patients with gastroesophageal reflux disease present symptoms after administration of 20-mg vonoprazan, the possibility of pathophysiologies other than acid reflux should be considered.

• Clinical Endoscopy
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• v.57 no.4
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• pp.549-551
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• 2024

• Clinical Endoscopy
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• v.57 no.4
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• pp.417-423
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• 2024

Since the introduction of vonoprazan, a potassium-competitive acid blocker (P-CAB), it has been demonstrated to reversibly inhibit gastric acid secretion by engaging in potassium-competitive ionic binding to H⁺/K⁺-ATPase. In contrast, proton pump inhibitors (PPIs) achieve H⁺/K⁺-ATPase inhibition through covalent binding to cysteine residues of the proton pump. Reported cases have indicated an emerging trend of P-CAB-related gastropathies, similar to those associated with PPIs, as well as unique gastropathies specific to P-CAB use, such as the identification of web-like mucus. Pathologically, parietal cell profusions, which show a positively correlated with hypergastrinemia, have a higher incidence in P-CAB users compared to PPI users. Thus, this review aims to summarize the endoscopic and pathological findings reported to date concerning P-CAB-related gastric mucosal lesions. Additionally, it seeks to discuss the differences between the PPIs and P-CABs in terms of the formation and frequency of associated gastropathies. This review highlights the evident differences in the mechanism of action and potency of acid inhibition between P-CABs and PPIs, notably contributing to differences in the formation and frequency of associated gastropathies. It emphasizes the necessity to distinguish between P-CAB-related and PPI-related gastropathies in the clinical setting.