Effect on bone turnover markers of once-yearly intravenous infusion of zoledronic acid versus daily oral risedronate in patients treated with glucocorticoids

Objective: Long-term glucocorticoid use is accompanied by rapid bone loss; however, early treatment with bisphosphonates prevents bone loss and reduces fracture risk. The aim of this study was to examine the effects of two bisphosphonates, i.v. zoledronic acid (ZOL) versus oral risedronate (RIS), on bone turnover markers (BTMs) in subjects with glucocorticoid-induced osteoporosis (GIO). Methods: Patients were randomly stratified according to the duration of pre-study glucocorticoid therapy [prevention subpopulation (ZOL, n = 144; RIS, n = 144) ≤3 months, treatment subpopulation (ZOL, n = 272; RIS, n = 273) >3 months]. Changes in β-C-terminal telopeptides of type 1 collagen (b-CTx), N-terminal telopeptide of type I collagen (NTx), procollagen type 1 N-terminal propeptide (P1NP) and bone-specific alkaline phosphatase (BSAP) from baseline were measured on day 10 and months 3, 6 and 12. Results: At most time points, there were significantly greater reductions (P<0.05) in the concentrations of serum β-CTx, P1NP and BSAP and urine NTx in subjects on ZOL compared with RIS in both males and females of the treatment and prevention subpopulations. In pre- and post-menopausal women, there were significantly greater reductions in the concentrations of BTMs with ZOL compared with RIS. At 12 months, ZOL had significantly greater reductions compared with RIS (P<0.05) for β-CTx, P1NP, BSAP and NTx levels, independent of glucocorticoid dose. Conclusions: Once-yearly i.v. infusion of ZOL 5mg was well tolerated in different subgroups of GIO patients. ZOL was non-inferior to RIS and even superior to RIS in the response of BTMs in GIO patients.