Based on recent findings from the largest osteoporosis study to date, researchers at UC San Francisco are calling an investigational drug for postmenopausal women an excellent new weapon in the fight against osteoporosis. In a placebo-controlled 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 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.
As further indication of the drug's effectiveness, 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 is published in the October 13 issue of the Journal of American Medical Association.
"Risedronate has also been shown to increase bone mass, stop bone loss, and produce healthy bones in women with established postmenopausal osteoporosis," said Steven T. Harris, MD, chief of the Osteoporosis Clinic at UC San Francisco and lead author of the study.
The bone mineral density (BMD) of women in the study who received risedronate increased significantly compared to those who took a placebo. BMD increased at the spine (5.4% versus 1.1%); neck (1.6% versus -1.2%); hip (3.3% versus -0.7%); and forearm (0.2% versus -1.4%), Harris said.
He added that risedronate was also 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. Each woman also took 1,000 mg of calcium each day, and those who had vitamin D deficiency took up to 500 international units (IU) of vitamin D daily.
Risedronate 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-fracture in her or his lifetime. In the United States, expenditures for osteoporotic and associated fractures totaled nearly $14 billion in 1995 alone.
The study was funded by Procter & Gamble, who developed risedronate, and Hoechst Marion Roussel.
Other study researchers include Douglas W. Axelrod, MD, PhD, Procter & Gamble; Jacques Brown, MD, Universitaire de Quebec; Charles H. Chesnut, III, MD, University of Washington, Seattle; Erik F. Eriksen, MD, Aarhus Amtssygehus, Aarhus, Denmark; Harry K. Genant, MD, professor of medicine, radiology, epidemiology and orthopedic surgery, University of California, San Francisco; Thomas Hangartner, PhD, Wright State University, Dayton, Ohio; Mohammad S. Hoseyni, PhD, Procter & Gamble Pharmaceuticals, Cincinnati, Ohio; Michael Keller, MD, San Diego Arthritis & Osteoporosis Medical Clinic, San Diego, California; Clark D. McKeever, MD, reSearch for Health, Houston, Texas; Paul D. Miller, MD, Colorado Center for Bone Research, Lakewood, Colorado; and Nelson B. Watts, MD, Emory University, Atlanta, Georgia.