New osteoporosis drug - alendronate sodium

Harvard Health Letter, April, 1996

A new medication that slows bone loss while increasing skeletal mass has osteoporosis experts cautiously optimistic that they are gaining ground on this debilitating disease.

An international group of researchers from 12 institutions analyzed the effects of alendronate sodium (sold as Fosamax) in 994 postmenopausal women with osteoporosis. For three years, the women took 5, 10, or 20 mg doses of alendronate, a combination of these, or a placebo, along with 500 mg of calcium daily. The researchers then measured the women's bone mineral density using a technique called dual-energy x-ray absorptiometry.

After three years, the women taking alendronate showed a 3-9% increase in bone density, while the placebo group lost bone. The 10 mg dose proved to be the most effective in increasing bone mass, and the increases were similar regardless of skeletal structure or age. During the study, 6.2% of the women in the placebo group had new vertebral (spinal) fractures compared with 3.2% of women who took alendronate.

Fosamax belongs to the class of drugs called bisphosphonates, which slow the body's natural resorption of bone. Etidronate (Didronel) is another in this group used to treat osteoporosis, but it can stimulate the formation of weak abnormal bone unless it is given cyclically. Fosamax can be taken continuously and doesn't appear to have this effect. But because bisphosphonates can accumulate in the skeleton, more studies are needed to evaluate the drugs' long-term safety.

For now, estrogen therapy for women, calcium supplements, and exercise are the best ways to prevent osteoporosis. David Slovik, chief of medicine at Spaulding Rehabilitation Center and assistant professor of medicine at Harvard, said Fosamax may well become the first-line treatment for osteoporosis once the condition has been diagnosed. (New England Journal of Medicine, November 30, 1995, pp. 1437-1443.)