The Food and Drug Administration (FDA) in 2009 approved a new use for zoledronic acid, a bone drug also known as Reclast, finding that one dose given every two years will help prevent postmenopausal osteoporosis. 

Reclast was already approved in the United States as a once-yearly intravenous infusion to treat the disease.

The FDA based its decision on a two-year randomized controlled trial of 581 postmenopausal women over the age of 45 with osteopenia, or low bone mass. Osteopenia affects an estimated 22 million women in the U.S. and puts them at higher risk of developing osteoporosis and increases their risk of bone fractures.

Researchers found that zoledronic acid increased bone mineral density compared to a placebo by 6.3 percent in those with early menopause and by 5.4 percent for those in later stages of menopause.

Mone Zaidi, MD, PhD, director of The Mount Sinai Bone Program at Mount Sinai School of Medicine in New York City is a national spokesman for zoledronic acid and was involved in the first set of clinical trails of the drug. He says the big benefit here is in the dosing.

“I think in terms of convenience, it’s much better," Dr. Zaidi said. “A woman comes for a bone density test every two years and at the same time she can be infused with the drug.”

The amount of medicine in the infusion stays the same – 5 mg of zoledronic acid. The side effects are the same as well. They include fever, muscle and joint pain, headache, nausea, vomiting and diarrhea. In rare cases, zoledronic acid has been associated with reports of a serious condition called osteonecrosis, or bone death, in the jaw.

This treatment is available immediately, but the FDA says the drug should not be given to patients who are pregnant, nursing or those who have low blood calcium, kidney problems or an allergy to zoledronic acid.