180 postmenopausal women with osteopenia were randomly allocated to receive either 1mg, 2.5 mg, or 5 mg intravenous infusion of zoledronate or a placebo. The purpose of this trial was to determine the optimal dosing regimen of zoledronate. Results indicated that a single administration of a 1 mg or 2.5 mg dose of intravenous zoledronate produces antiresorptive effects for at least two years, although the 1 mg antiresorptive effects appear to slow after 12 months. At 2 years post-intervention, the change in bone mineral density (BMD) and bone turnover markers in the 2.5 mg dose group were similar to effects induced by 5 mg.