Osteoporosis Drug Reduces Risk of Bone Fractures

October 12, 1999
News Office: Abby Sinnott (415) 885-7277

Researchers at UCSF are calling an investigational drug for postmenopausal women an excellent new weapon in the fight against osteoporosis.

In a study of 2,458 post-menopausal women with osteoporosis, researchers found that after three years of treatment with the drug, called risedronate, the incidence of new vertebral fractures of the spine (vertebral) was reduced by 41 percent and non-vertebral fractures by 39 percent among women taking risedronate compared to those receiving a placebo.

After just one year of treatment with risedronate, the incidence of new spinal fractures was reduced by 65 percent among women in the risedronate group compared to those in the placebo group.

The study was published in the Oct. 13 issue of the Journal of American Medical Association. "Risedronate has also been shown to prevent fractures, increase bone mass, stop bone loss, and produce healthy bones in women with established postmenopausal osteoporosis," said Dr. Steven T. Harris, an endocrinologist, chief of the Osteoporosis Clinic at UCSF Medical Center and lead author of the study. "The drug was also well tolerated among women in the study, with an overall safety profile similar to that of a placebo."

The bone mineral density (BMD) of women in the study who received risedronate also increased significantly compared to those who took a placebo. BMD increased at the spine (5.4 percent versus 1.1 percent); neck (1.6 percent versus 0.5 percent); hip at the femoral neck (3.3 percent versus -0.7 percent); and forearm at the femoral trochanter (0.2 percent versus -1.4 percent), Harris said.

He added that risedronate als was well tolerated among study participants. Although upper gastrointestinal (GI) problems are common in older women, the incidence of GI problems was the same among women in the risedronate and placebo groups.

Women who participated in the study were postmenopausal with at least one previous vertebral fracture. During the three-year, randomized, double-blind, multicenter trial (110 study centers in North America), participants were randomized to receive either a daily oral treatment of risedronate (2.5 mg or 5 mg) or placebo for up to three years. Each woman also took 1,000 mg of calcium each day, and those who had a vitamin D deficiency took up to 500 international units (IU) of vitamin D daily.

Risedronate is a bisphosphonate that binds to bones and protects against bone loss. It has been shown to be effective in the treatment of Paget's disease and other metabolic bone diseases. However, it has not been evaluated as a treatment for postmenopausal osteoporosis, a bone-weakening disease.

According to the National Osteoporosis Foundation, more than 50 million Americans may be affected by osteoporosis over the next century. One in two American women and one in eight American men over age 50 will suffer an osteoporosis-related fracture in her or his lifetime. In the United States, osteoporosis results in 1.5 million fractures each year, over 400,000 hospital admissions, more than 44 million patient days in nursing homes and $13.8 billion in health care expenditures among women and men.

The study was funded by Procter & Gamble, which developed risedronate, and Hoechst Marion Roussel.

Other study researchers include Dr. Douglas W. Axelrod, Procter & Gamble; Dr. Jacques Brown, Universitaire de Quebec; Dr. Charles H. Chesnut, III, University of Washington, Seattle; Dr. Erik F. Eriksen, Aarhus Amtssygehus, Aarhus, Denmark; Dr. Harry K. Genant, professor of medicine, radiology, epidemiology and orthopedic surgery, UCSF; Thomas Hangartner, Wright State University, Dayton, Ohio; Mohammad S. Hoseyni, Procter & Gamble Pharmaceuticals, Cincinnati, Ohio; Dr. Michael Keller, San Diego Arthritis & Osteoporosis Medical Clinic, San Diego, California; Dr. Clark D. McKeever, reSearch for Health, Houston, Texas; Dr. Paul D. Miller, Colorado Center for Bone Research, Lakewood, Colorado; and Dr. Nelson B. Watts, Emory University, Atlanta, Georgia.