Intravenous Bisphosphonate Therapy for Postmenopausal Women with Low Bone Mass

At 24 months, mean spinal BMD was substantially higher, relative to baseline, among women in the single-dose (4.4% change) and two-dose (5.2% change) treatment arms than in the placebo arm (–1.31% change). Increases in BMD at the hip were also significantly greater with active treatment than with placebo. Rates of serious adverse events were similar in the three treatment arms. Pain, fever, chills, myalgia, and nausea occurred more often with zoledronic acid than with placebo; most symptoms occurred within 3 days of infusion and lasted for 3 days.

Comment: In addition to facilitating treatment adherence, intravenous bisphosphonate therapy (which can be administered at infusion centers) is useful when gastrointestinal concerns preclude use of oral bisphosphonates. These trial participants had low bone mass (the authors do not use the term "osteopenia," which might inappropriately connote high fracture risk). Updated guidelines from the National Osteoporosis Foundation recommend that prescription therapy be considered for postmenopausal women who do not have osteoporosis but who have moderate or high fracture risk based on a combination of BMD and clinical risk factors. The authors note that, based on WHO FRAX assessment (which was not available when the study began), many of these participants would not be considered candidates for prescription therapy. Zoledronic acid prevents fractures in osteoporotic women; these results indicate that it is also suitable for preventing loss of BMD in women with low bone mass who are appropriate candidates for pharmacologic therapy.