Dual Effects of Rabeprazole on Solid-Phase Gastric Emptying Assessed by the 13C-Octanoate Breath Test

BACKGROUND/AIMS: Knowledge is limited regarding the effects of rabeprazole on gastric emptying. This randomized, open, crossover study was undertaken to investigate the effects. METHODS: In 24 healthy volunteers (13 men and 11 women, aged 22-53 years), solid emptying was assessed twice using the 13C-octanoate breath test. On one occasion, the subjects received 20 mg rabeprazole for the preceding 2 days and 1 h before the test. On another occasion, they underwent no pretreatment. The time course of cumulative recovery of 13CO2 in breath was fitted to z(t)=m(1-e-kt)beta-1, and regression constants of k and beta were determined. The half 13CO2 excretion time (t(1/2)b)) and the time of maximal excretion (tmax) were calculated. Under the crossover protocol, k and beta can describe the emptying features more precisely; a larger (smaller) beta indicates a slower (faster) emptying in the early phase, and a larger (smaller) k indicates a faster (slower) emptying in the later phase. Between the two occasions, k, beta, t(1/2)b, and tmax were compared. RESULTS: Rabeprazole significantly decreased k and beta, significantly prolonged t(1/2)b, but tmax remained unchanged. CONCLUSION: Rabeprazole has dual effects on solid emptying: an initial acceleration with a subsequent deceleration, resulting in an overall delay.