Profound gastric mucosal changes and severe rebound acid hypersecretion after long-term Vonoprazan use: A case report

Abstract

Vonoprazan is a novel acid blocker with greater potency than proton pump inhibitors. A Japanese study reported no significant safety concerns over 5 years of Vonoprazan use; however, elevated serum gastrin and increased parietal cell and foveolar hyperplasia were observed, and long-term safety data beyond 5 years are limited. We report a case that used Vonoprazan for 6 years, complicated by significant gastric epithelial changes during treatment and acute duodenal mucosal lesions following its discontinuation. A 76-year-old, treated with proton pump inhibitors for over 10 years, was switched to Vonoprazan due to his worsening symptoms. After its use, hemorrhagic hyperplastic polyps became prominent. Given concerns about Vonoprazan's effect on the gastric epithelium, the medication was changed to high-dose H2 blocker therapy. Two months later, the patient complained of vomiting and black tarry stools. Esophagogastroduodenoscopy revealed a significant reduction of gastric polyps but multiple erosions and ulcers in the duodenum. This case indicates the potent effects of Vonoprazan on the gastric mucosa and the risk of severe rebound acid hypersecretion after its long-term use.

Keywords: Vonoprazan; gastric mucosa; gastroesophageal reflux; proton pump inhibitors; rebound acid hypersecretion.

FIGURE 1

(a–d) Endoscopic images (a, b) before the initiation of Vonoprazan therapy. (c, d) after 19 months of Vonoprazan use, linear and spotty redness and multiple small hyperplastic polyps in the body became prominent in addition to previously observed fundic gland polyps.

FIGURE 2

(a–d) Endoscopic images (a, b) after 59 months of Vonoprazan use, showing a hemorrhagic polyp (blue arrow) before resection. (c, d) After 69 months of Vonoprazan use, revealing the growth of new polyps was growing following the resection (yellow circle).

FIGURE 3

(a–c) Endoscopic images after switching to H2 blockers, showing a significant deduction of polyps in the stomach. (d) Endoscopic images revealing ulcers in the duodenum. This image shows an ulcer located in the superior duodenal angle.

FIGURE 4

(a–c) Histological images. (a) Hematoxylin and eosin staining showing parietal cell hyperplasia in the gastric body, (b) Anti‐synaptophysin staining showing increased enterochromaffin‐like cells in the gastric body, and (c) Anti‐gastrin staining showing G cell hyperplasia in the antrum. Scale bars; 250 µm.