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A single IV dose of the bisphosphonate drug zoledronic acid has been shown to increase bone density at 1 year in women with osteopenia or osteoporosis (Journal Watch Mar 8 2002 and N Engl J Med 2002 Feb 28; 346:653). To determine whether once-yearly dosing reduces fracture rates, researchers conducted this industry-sponsored randomized trial involving 7765 women (age range, 65–89) who had osteopenia with radiologic evidence of vertebral fracture or osteoporosis at the femoral neck.
Women received a 15-minute infusion of zoledronic acid (5 mg) or placebo yearly. At 3 years (and 3 doses), the incidence of new fractures was significantly lower in the zoledronic-acid group than in the placebo group — 3.3% versus 10.9% for radiographic vertebral fractures, 0.5% versus 2.6% for clinical vertebral fractures, and 1.4% versus 2.5% for hip fractures. Bone density at both the hip and lumbar spine increased by about 6% in the zoledronic-acid group, compared with the placebo group. Adverse events associated with zoledronic acid included flu-like symptoms, a 1% incidence of a transient rise in serum creatinine, and a 1% incidence of “serious atrial fibrillation.”
Black DM et al. Once-yearly zoledronic acid for treatment of postmenopausal osteoporosis. N Engl J Med 2007 May 3; 356:1809-22.
Comment
Given the complex instructions for oral administration of bisphosphonates, the idea of a single yearly intravenous dose of bisphosphonate is attractive. However, it is unclear whether patients will readily accept IV therapy for osteopenia and osteoporosis. Moreover, the unexpected occurrence of serious atrial fibrillation (defined elsewhere as life threatening or resulting in hospitalization or disability) requires further investigation. Currently, zoledronic acid (Zometa) is approved only for treatment of hypercalcemia of malignancy and cancer-related bone complications.