Fexuprazan (DWP14012), a potassium-competitive acid blocker, is a medical formulation prescribed to inhibit the secretion of gastric acid. The present study encompasses a comparative evaluation of pharmacokinetic (PK) analysis between the previous (reference) and size-reduced (test) formulation of fexuprazan 20 mg in healthy subjects. The study employed a randomized, open-label, single-dose, 2-sequence, 2-period, crossover design with a 7-day wash-out between periods. A total of 24 subjects were enrolled in this randomized study. During each period, the 21 subjects received either the test or reference formulation. Blood samples were collected at multiple time point ranging from 0 (pre-dose) to 48 hours post-dosing for PK analysis. The calculated PK parameters were considered bioequivalent when the 90% confidence intervals (CIs) of the geometric mean ratios (GMRs) were within the bioequivalence limit of 0.8-1.25. Safety and tolerability were included in the evaluation. A total of 20 subjects completed the study. Point estimates (90% CIs) of the GMRs were 1.1014 (0.9892-1.2265) for the maximum plasma concentration and 1.0530 (0.9611-1.1536) for the area under the plasma concentration-time curve from zero to the time of the last quantifiable concentration, between the test and reference formulations. The reference and size-reduced test formulations of fexuprazan were well tolerated with no reports of serious adverse events. In conclusion, size-reduced and previous formulations of fexuprazan 20 mg were bioequivalent with regard to PKs, safety and tolerability.