Abstract Background Current treatment options for equine gastric ulcer syndrome (EGUS), such as omeprazole—a proton pump inhibitor (PPI)—have notable limitations, including the need for administration on an empty stomach. Potassium‐competitive acid blockers (P‐CABs), such as vonoprazan, are a newer class of acid suppressants that offer several advantages over PPIs in humans and may provide similar benefits in horses. Objectives To describe the pharmacokinetics and effect of a single oral dose of vonoprazan on intragastric pH in horses. We hypothesised that vonoprazan would follow linear kinetics across the doses studied and effectively increase intragastric pH. Study Design Prospective, randomised four‐way balanced crossover study. Methods Six horses received vonoprazan (0.5 and 1 mg/kg), omeprazole (4 mg/kg) and water (60 mL). Blood samples were collected prior to and up to 72 h post‐administration. Plasma vonoprazan concentrations were measured using liquid chromatography–tandem mass spectrometry, and non‐compartmental and compartmental pharmacokinetic analyses were performed. Intragastric pH was continuously recorded 12 h before and 24 h after each treatment. The percentage of time pH remained above 4 was compared among treatments. Results For 0.5 and 1 mg/kg vonoprazan, respectively, C max was 23.7 ± 14.0 and 55.8 ± 18.1 ng/mL (mean ± SD); T max was 0.875 (0.25–3.0) and 0.625 (0.08–1.0) h (median and range); and terminal half‐life was 6.12 ± 1.65 and 6.29 ± 1.86 h (mean ± SD). At 1 mg/kg, vonoprazan significantly increased the percentage of time pH >4 compared to pre‐treatment (91.85% vs. 85.5%; p = 0.007) and placebo (90.28 ± 5.6% vs. 5.68 ± 39%; p = 0.021). Main Limitation Small sample size which may impact clinical applicability of observed changes and potential variability in pH probe positioning. Conclusion Vonoprazan was well tolerated and effectively increased and maintained intragastric pH above 4 at the 1 mg/kg dose in horses.
Morales et al. (Wed,) studied this question.