Acid-suppressive effects of rabeprazole: Comparing 10 mg and 20 mg twice daily in Japanese Helicobacter pylori-negative and -positive CYP2C19 extensive metabolisers

Abstract

Background Rabeprazole 10 mg b.i.d. is often administered as therapy for eradication of Helicobacter pylori (H. pylori) and is also proposed as therapy for refractory gastro-oesophageal reflux disease. However, there has not been a comprehensive assessment of its acid-suppressive effects. Aims To compare the acid-suppressive effects of rabeprazole 10 mg b.i.d. with 20 mg b.i.d. considering H. pylori status. Subjects Thirteen H. pylori-negative and eleven H. pylori-positive Japanese CYP2C19 extensive metabolisers (<35 years). Methods Intragastric pH was measured for 24 h three times in a randomised manner; on day 7 of the repeated administration of rabeprazole 10 mg b.i.d. or 20 mg b.i.d., or a placebo. Results In median intragastric pH value and percent time of pH > 3.0, >4.0, >5.0, >6.0, and >7.0 for 24 h, no significant differences were observed between the two doses in either H. pylori-negative or H. pylori-positive subjects. At either dose, these parameters were significantly higher in H. pylori-positive subjects than in H. pylori-negative subjects. Nocturnal acid breakthrough occurred in seven and two of the thirteen H. pylori-negative subjects and one and two of the eleven H. pylori-positive subjects at each dose, respectively. Conclusions The effects of rabeprazole 10 mg b.i.d. were equal to those of 20 mg b.i.d. in H. pylori-positive subjects; whereas in H. pylori-negative subjects, 20 mg b.i.d. was superior for prevention of nocturnal acid breakthrough.