Alfacalcidol Increases the Therapeutic Efficacy of Ibandronate on Bone Mineral Density in Japanese Women with Primary Osteoporosis.

Bisphosphonates (BPs) increase bone mineral density (BMD) through the inhibition of osteoclast activity. Among BPs, ibandronate (IBN) is a strong inhibitor of bone resorption. However, the effects of a vitamin D analogue, alfacalcidol (ALF), on IBN treatment for osteoporosis is unknown. Fifty-three treatment-naïve post-menopausal women with primary osteoporosis were recruited and divided into IBN-treatment group (IBN group) and IBN with ALF group (IBN/ALF group). IBN (1.0 mg) was intravenously injected once a month, with or without oral ALF (1.0 μg/day). Ultimately, 19 subjects in IBN group and 26 in IBN/ALF group were analyzed. Bone turnover markers were examined at 4, 6, 12, and 18 months, and BMD was measured at 6, 12, and 18 months. Compared with pre-treatment, bone turnover markers significantly decreased in both groups after 4 months. The levels of serum N-terminal propeptide of type-1 procollagen and tartrate-resistant acid phosphatase-5b, and urinary N-terminal telopeptide of type-I collagen were significantly lower in IBN/ALF group than those in IBN group at 12 months. Lumbar 1-4 (L)-BMD significantly increased from 6 months in IBN/ALF group and at 18 months in IBN group. L-BMD was significantly higher in IBN/ALF group (6.6% increase) than in IBN group (3.4%) at 18 months. Total hip (H)-BMD significantly increased from 6 months in IBN/ALF group and tended to improve in IBN group. H-BMD was significantly higher in IBN/ALF group (4.8%) than in IBN group (3.2%) at 18 months. In conclusion, treatment with ALF in combination with IBN improves BMD in post-menopausal women with osteoporosis.