Abstract

OBJECTIVES: To evaluate safety, tolerability, pharmacokinetics, and pharmacodynamics of TAK-438 (vonoprazan, a potassium-competitive acid blocker) in healthy male subjects. METHODS: In two phase I, randomized, double-blind, placebo-controlled, single rising-dose studies, healthy male subjects (Japan N=84; UK N=63) received a single TAK-438 dose (1-120 mg in Japan and 1-40 mg in the UK). Assessments included safety, tolerability, pharmacokinetics, and pharmacodynamics (intragastric pH). RESULTS: Plasma concentration-time profiles of TAK-438 at all dose levels showed rapid absorption (median Tmax up to 2 h). Estimated mean elimination half-life was up to 9 h. Exposure was slightly greater than dose proportional. No clear difference in TAK-438 pharmacokinetics was observed between Japanese and non-Japanese subjects. Acid suppression was dose dependent and similar in both studies. The 24-h intragastric pH ≥4 holding time ratio with 40 mg TAK-438 was 92% in Japan and 87% in the UK. TAK-438 was well tolerated, with no adverse events reported in Japanese subjects; 10 of 63 UK subjects experienced 12 treatment-emergent adverse events (non-serious). Increases in serum gastrin and pepsinogen I and II concentrations were observed at doses ≥10 mg, but there were no changes in alanine aminotransferase concentrations. CONCLUSIONS: Single oral doses of TAK-438 20-120 mg caused rapid, profound, and 24-h suppression of gastric acid secretion in healthy male subjects, regardless of geographical region, and TAK-438 was well tolerated at all doses studied, making it a potential alternative to proton pump inhibitors for the treatment of acid-related disorders.