Upper gastrointestinal bleeding (UGIB) remains an important medical emergency. While the annual incidence having decreased from about 100/100,000 adults in 1990s to 61-78/100,000 persons in 2009-2012 , 30-day mortality remains up to 11% . Despite advancement in various endoscopic haemostatic technology, peri-endoscopic management remains paramount to satisfactory outcome in acute non-variceal gastrointestinal bleeding (NVGIB), especially for peptic ulcer bleeding. Indeed, recurrent bleeding leads to prolonged hospital stay and is an independent risk factor for mortality . Current international guidelines advocate the use of high dose proton pump inhibitors (PPI), as defined as ≥80mg daily for ≥3 days, to be given intermittently or continuously after successful endoscopic haemostatic therapy . It is hypothesized that the lowering of gastric acidity by PPI can facilitate formation and stability of clot, as pepsin-induced clot lysis is inhibited when pH is above 4-5 . Studies including RCTs have shown that PPI therapy markedly reduced further bleeding (RR = 0.43,0.33-0.56), mortality (RR = 0.41, 0.22-0.79) and surgery compared (RR = 0.42, 0.25-0.71) with placebo or no treatment . When compared to other acid suppressants such as H2-blocker (H2B), studies have demonstrated superiority of PPI therapy in reducing rebleeding, but not mortality or need for further intervention . Study has shown PPI infusion can achieve intragastric pH 6 holding time ratio (HTR) for 67.8% over first 24 hour and intragastric pH 4 HTR for 90.5% of the period , while the pH 6 HTR for bolus PPI every 12 hour has been shown to be 49.0% . Despite the apparent difference in effect on intragastric pH, the optimal dose of PPI therapy is still not well defined, with data showing comparable outcome between infusion and intermittent dosing.

In recent years, Vonoprazan (VPZ), an oral potassium-competitive acid blocker (P-CAB) has emerged as an alternative potent acid-suppressant. It was first launched in Japan in February 2015 and has shown satisfactory effect and safety profile in treatment of reflux oesophagitis, H. Pylori eradication, NSAID-associated ulcer, endoscopic submucosal dissection (ESD) induced gastric ulcers and peptic ulcer disease, etc . A RCT has demonstrated non-inferiority of Vonoprazan when compared with lansoprazole in peptic ulcer treatment, while other studies also showed non-inferiority of Vonoprazan to PPI treatment in high risk conditions such as patient on dual-antiplatelet therapy or prevention of bleeding from endoscopic submucosal dissection induced gastric ulcers . It has a faster onset of action in 1 day (3-5 days in PPI), and is more stable in acidic condition than PPI. Studies has demonstrated that Vonoprazan 20 mg once daily achieves 63% pH4 HTR after 24 hours; and the median pH4time (intragastric pH ≥ 4 over 24h after ≥ 5 days of therapy) for Vonoprazan after 7 days of 10, 20, 30, and 40 mg once daily was 60.2%, 85.2%, 90.1%, and 93.2%. . Extrapolating those results to pH4time for PPIs suggests that 10 mg of Vonoprazan once daily is approximately equivalent to 60 mg of omeprazole equivalents (OE), or 40mg of esomeprazole; and 20 mg is equivalent to 60 mg OE bid, or esomeprazole 40 mg bid .

While many studies compared Vonoprazan against PPI in the treatment of reflux oesophagitis, H. Pylori eradication, and gastric ulcers; thus far, there is a paucity of data on use of Vonoprazan on bleeding peptic ulcers. Here, we perform a multicenter randomized controlled trial (RCT) to compare the efficacy of oral Vonoprazan against standard high dose PPI therapy, in the form of high dose intravenous bolus injection (80mg) followed by continuous infusion for 72 hours (8mg/h), in bleeding peptic ulcers that had received successful endoscopic haemostasis. With the hypothesis that 10mg Vonoprazan is approximately equivalent to 40mg of esomeprazole, the total volume of bolus injection and 72 hours infusion of 656mg esomeprazole is approximately equivalent to 164mg Vonoprazan. Therefore, we propose a dose of 40mg every 12hours for 72hours for the treatment of bleeding peptic ulcers. As part of the study, we also investigate the effect of Vonoprazan on intra-gastric pH in this clinical setting.