Effects of Rabeprazole on Plasma Gastrointestinal Peptides in Healthy Humans

Abstract

Rabeprazole sodium (rabeprazole), a proton pump inhibitor (PPI), is widely used in the treatment of peptic ulcer and gastroesophageal reflux disease. Recently, some antiulcer medicines have been elucidated pharmacologically from the viewpoint of gut-regulated hormone levels. We examined the effects of rabeprazole on plasma levels of gastrointestinal peptides [gastrin, somatostatin, motilin, substance P, and calcitonin gene-related peptide (CGRP)]. Rabeprazole at a dose of 20 mg or placebo was orally administered to 5 healthy male volunteers aged 25-30 years. Venous blood samples were taken before and 30, 60, 90, 120, 180, 240, and 360 min after administration. Plasma peptide levels were measured using a sensitive enzyme immunoassay. Compared with the response of the placebo group, rabeprazole caused significant (p < 0.05) increases in gastrin-, somatostatin-, and CGRP-like immunoreactive substance (IS) at 360, 180, and 240 min, respectively. Rabeprazole significantly decreased motilin-IS levels at 180 min compared with the placebo group. However, rabeprazole had no effect on plasma substance P-IS levels. Although rabeprazole has potent antisecretry effects, the agent may have little effect on gastrointestinal peptides.