Comparison of effect of an increased dosage of vonoprazan versus vonoprazan plus lafutidine on gastric acid inhibition and serum gastrin.

BACKGROUND: Vonoprazan, a novel potassium-competitive acid blocker, elicits potent acid inhibition and hypergastrinemia at a dose of 20 mg. Its recommended maintenance dose for gastro-esophageal reflux disease is 10 mg, which is sometimes insufficient for preventing nocturnal acid breakthrough (NAB). Concomitant use of a histamine 2 receptor antagonist (H2RA) is effective for NAB. However, further acid inhibition by addition of H2RA has concern of hypergastrinemia again. Lafutidine (H2RA) is known to stimulate somatostatin release.

AIMS: The aim of this study is to compare the levels of acid inhibition and serum gastrin attained by addition of lafutidine to vonoprazan 10 mg with levels after a dose increase of vonoprazan from 10 to 20 mg.

METHODS: Thirteen healthy volunteers underwent 24-h intragastric pH monitoring and serum gastrin measurements on day 7 of three different regimens: vonoprazan 10 mg, vonoprazan 10 mg plus lafutidine 10 mg, and vonoprazan 20 mg.

RESULTS: Median pH 4 holding time ratios (range) by vonoprazan 10 mg, vonoprazan 10 mg plus lafutidine 10 mg, and vonoprazan 20 mg were 82% (47-88%), 88% (76-93%), and 99% (95-100%) while those at nighttime from 10 p.m. to 8 a.m. were 94% (29-100%), 100% (95-100%), and 100%, respectively. The incidences of NAB with vonoprazan 10 mg, vonoprazan plus lafutidine, and vonoprazan 20 mg were 38, 8, and 0%, respectively. Respective serum gastrin levels were 420 (173-508), 323 (196-521), and 504 (400-812) pg/ml.

CONCLUSION: Addition of lafutidine 10 mg to vonoprazan 10 mg achieved sufficient acid inhibition, especially at nighttime, without further increase of serum gastrin levels.