A small randomized trial from Italy found that while zoledronic acid (Reclast) slows bone loss in osteoporosis, it may also slow bone formation. Perhaps combination therapy is required.
Catalano A, Morabito N, Basile G, et al. Zoledronic Acid Acutely Increases Sclerostin Serum Levels in Women with Postmenopausal OsteoporosisThe Journal of Clinical Endocrinology & Metabolism Published online before print April 17, 2013, doi: 10.1210/jc.2012-4039
A small randomized trial from Italy found that while zoledronic acid (Reclast) slows bone loss among older women with osteoporosis, it also increases a biomarker that stops bone formation -- suggesting that combination therapy may be needed as a counter measure.
Serum sclerostin, a circulating inhibitor of bone formation thought to be produced by osteocytes, is higher in postmenopausal women and increases with age.
Reclast is given as a single intravenous injection every two years to prevent osteoporosis after menopause.
The prospective intervention study enrolled 40 postmenopausal women with low T-scores and evidence of vertebral fractures, randomizing them to 5 mg of IV zoledronic acid or a placebo. Both groups took calcium carbonate (1000 mg) and cholecalciferol (800 IU) supplements.
Women in the zoledronic acid group showed elevated sclerostin 2 days after the infusion and a three-fold increase from baseline by day 7, returning almost to baseline at day 360. The bone resorption marker type 1 collagen was reduced by day 2, but levels of a bone formation marker, bone-specific alkaline phosphatase, were lower by day 7. No changes were observed in the placebo group.
The lead author suggested that an “innovative combination therapy” adding selective antibodies to block sclerostin could simultaneously stop bone loss and encourage new bone formation in zoledronic acid users.