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

BackgroundRabeprazole 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.AimsTo compare the acid-suppressive effects of rabeprazole 10 mg b.i.d. with 20 mg b.i.d. considering H. pylori status.SubjectsThirteen H. pylori-negative and eleven H. pylori-positive Japanese CYP2C19 extensive metabolisers (<35 years).MethodsIntragastric 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.ResultsIn 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.ConclusionsThe 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.