NEW YORK (Reuters Health) – In postmenopausal women with osteopenia, zoledronic acid, given either once-yearly or as a single infusion, is well tolerated and effective in preventing bone loss at the lumbar spine and proximal femur for up to 2 years.

That’s according to randomized controlled trial published in the November issue of Obstetrics and Gynecology.

In postmenopausal women with osteoporosis, the study team notes, “Once-yearly infusion of zoledronic acid 5 mg has been proven to reduce the risk of vertebral, hip and nonvertebral fractures and to increase lumbar spine and total hip bone mineral density (BMD) over 3 years.”

The current trial, which was supported by Novartis Pharma AG, Basel, Switzerland, involved 581 women without osteoporosis but with osteopenia — defined as a BMD T-score less than -1.0 and more than -2.5 at the lumbar spine and a BMD T-score greater than -2.5 at the femoral neck.

There were three study arms. One hundred ninety-eight women received 5-mg infusions of zoledronic acid twice: once at baseline and again at month 12. Another 181 women received 5 mg at baseline and placebo at month 12, and 202 received only placebo. Similar proportions of women in the three groups completed the study (91%, 85% and 93%, respectively).

At 24 months, both zoledronic acid groups had significant increases in mean BMD at the lumbar spine (5.18% in the 2-dose group and 4.42% in the single-dose group), whereas the placebo group had a slight decrease in average BMD at this site (-1.32%; p < 0.001 for both comparisons).

Similarly, both zoledronic acid regimens led to significantly greater increases, relative to placebo, in lumbar spine BMD at month 12 and for BMD at all proximal femur sites (total hip, femoral neck, trochanter) at months 12 and 24 (all p < 0.001), Dr. Michael McClung from the Oregon Osteoporosis Center in Portland and colleagues report.

Both zoledronic acid regimens led to significant reductions in bone turnover markers over time relative to placebo (all p < 0.001). During the second year, however, the changes were sustained to a greater extent in the women who had the repeat dose at 12 months.

The overall incidence of adverse events was similar in the three groups (10.6%, 9.4%, and 11.4%, with single-dose zoledronic acid, annual dosing, and placebo, respectively). Nineteen women experienced fractures during the study (six in the annual-dose group, four in the single-dose group and 9 in the placebo group).

No cases of atrial fibrillation, osteonecrosis of the jaw or any long-term effects on renal function were reported.

Reference:
Obstet Gynecol 2009;114:999-1007.