Effects of Rioprostil on Gastric Acid and Pepsin Secretion in Man: A Review of Studies in Healthy Volunteers

Abstract

Demol P, Singer MV, Dammann HG, Richardson CT, Weihrauch TR. Effects of rioprostil on gastric acid and pepsin secretion in man: a review of studies in healthy volunteers. Scand J Gastroenterol 1989, 24(suppl 164), 74-80

The antisecretory effect of rioprostil on acid and pepsin secretion stimulated by pentagastrin or a meal, or on the 24-h intragastric acidity is tested in four different studies in 33 healthy male volunteers using a double-blind, crossover design. The oral doses of rioprostil used are 50 μg, 100 μg, 150 μg, 200 μg, 300 μg and 600 μg; these are the results obtained: Rioprostil reduces basal H⁺ and pepsin output by more than 50%. Rioprostil, 300 μg and 600 μg, significantly reduces the 3-h pentagastrin-stimulated acid output by 43.5% and 58.9%, respectively, and the 3-h stimulated pepsin output by 41.1% and 66.5%, respectively (p = 0.01). Depending on the method used for intragastric titration the following percentages of inhibition of acid secretion are observed, 40%, 65%, and 75% with 150 μg, 300 μg, and 600 μg rioprostil respectively, with one method and 32%, 34%, and 79% with 25 μg, 50 μg, and 200 μg rioprostil respectively, with a somewhat modified technique. The differences observed in % inhibition between these two studies can be explained by the use of a different intragastric titration technique. Rioprostil, 300 μg and 600 μg, significantly inhibits night-time acid secretion (AUC x h, 2400h-0800h) by 52% and 73.5% when compared with placebo (p = 0.03). The calculated ED₅₀ for acid inhibition is 86.5 μg of rioprostil.

Key Words:

• Antisecretory effect
• meal stimulation
• rioprostil
• pentagastrin
• volunteers