Efficacy and Safety of Oral Ibandronate versus Intravenous Zoledronic Acid on Bone Metabolism and Bone Mineral Density in Postmenopausal Japanese Women with Osteoporosis

There are no published clinical reports comparing ibandronate (IBN) treatment and zoledronic acid (ZOL) treatment in Japanese postmenopausal osteoporotic patients. This investigation therefore compared the efficacy and safety of the drugs on improving bone metabolism and bone mineral density (BMD) in Japanese postmenopausal women with primary osteoporosis. Eighty-two treatment-naive primary osteoporotic female patients were randomly divided into IBN-treated or ZOL-treated groups. Bone turnover markers and BMD were examined immediately prior to treatment (baseline) and at 6, 12, 18, 24, and 30 months of therapy. Compared with baseline levels, the values of type 1 procollagen N-terminal propeptide, bone-specific alkaline phosphatase (BAP), urinary type-I collagen amino-terminal telopeptide (NTX), and tartrate-resistant acid phosphatase 5b were all significantly decreased at every time point in both groups apart from BAP at 30 months in the ZOL group, urinary NTX at 12 months in the ZOL group and at 24 and 30 months in both groups. Lumbar BMD values were significantly increased at 6, 12, 18, and 24 months in the IBN group and at 6 and 12 months in the ZOL group compared with pre-treatment levels. Hip BMD values were also significantly increased at 6, 12, 18, and 24 months in the IBN group and at 6, 12, and 18 months in the ZOL group compared with baseline values. The percentage changes of hip BMD at 18 and 24 months in the ZOL group were significantly higher than those in the IBN group (both p < 0.05). No remarkable adverse events were noted in either group. In conclusion, both IBN and ZOL significantly and safely improved bone turnover markers and BMD during 30 months of treatment in Japanese osteoporosis patients. The ZOL group tended to exhibit greater gains in BMD as compared with the IBN group, which merits further investigation.