Duration of antiresorptive activity of Zoledronate in postmenopausal women with osteopenia: a randomized, controlled multidose trial

Zoledronate is an intravenously administered bisphosphonate that has been used to reduce fracture risk in osteoporosis. But the optimal dosing regimen is still uncertain. Intravenous Zoledronate 5 mg annually reduces the risk of fracture while 5 mg every 2 years prevent bone loss. Therefore, the results of the present study demonstrated that the antiresorptive activity of single Zoledronate doses of 1–5 mg persist for at least 3 years in postmenopausal women with osteopenia.

Intravenous 5 mg Zoledronate decreases fracture risk yearly, and 5 mg every two years halts bone loss, although the optimal dosing regimens for these implications are unpredictable.

One hundred sixty females in their late postmenopause with osteopenia were selected and obtained a single baseline dose of placebo or 1 mg, 2.5 mg or 5 mg of Zoledronate. Change in the spine bone mineral density (BMD) was taken as the primary endpoint and changes serum markers of bone turnover and hip BMD were considered as secondary endpoints. 

The markers of bone turnover decreased, and BMD increased in a dose-dependent manner with Zoledronate. After two years, the 1-mg, 2.5-mg and 5-mg Zoledronate enhanced spine BMD and total hip BMD over placebo by (5.0% and 2.6%), (5.7% and 4.1%), and (5.7% and 4.7%), respectively.After 5 years,  the 1-mg, 2.5-mg and 5-mg Zoledronate enhanced (2.0% and 1.8%), (2.2% and 2.8%), and (5.1% and 5.4%) spine BMD and total hip BMD over placebo, respectively. In 1-mg, 2.5-mg, and 5-mg group, BMD persisted above baseline values for 2–3 years, 3–4 years, and at least five years, respectively. 

The antiresorptive activity of single 1–5 mg Zoledronate continues for at least three years within postmenopausal women with osteopenia.