A Proton Pump Inhibitor’s Effect on Bone Metabolism Mediated by Osteoclast Action in Old Age: A Prospective Randomized Study

BACKGROUND/AIMS: Proton pump inhibitors (PPIs) act by irreversibly binding to the H(+)-K(+)-ATPase of the proton pump in parietal cells and may possibly affect the vacuolar H(+)-ATPase in osteoclasts. METHODS: We investigated the effect of 8 weeks of PPI treatment on the parameters of bone turnover and compared PPI with revaprazan, which acts by reversibly binding to H(+)-K(+)-ATPase in proton pumps. This study was a parallel randomized controlled trial. For 8 weeks, either a PPI or revaprazan was randomly assigned to patients with gastric ulcers. The parameters of bone turnover were measured at the beginning of and after the 8-week treatment period. RESULTS: Twenty-six patients (PPI, n=13; revaprazan, n=13) completed the intention-to-treat analysis. After the 8-week treatment period, serum calcium and urine deoxypyridinoline (DPD) were increased in the PPI group (serum calcium, p=0.046; urine DPD, p=0.046) but not in the revaprazan group. According to multivariate linear regression analysis, age ≥60 years was an independent predictor for the changes in serum calcium and urine DPD. CONCLUSIONS: In elderly patients, administering a PPI for 8 weeks altered bone parameters. Our study suggested that PPIs might directly alter bone metabolism via the vacuolar H(+)-ATPase in osteoclasts.