Alendronate reported safe, well tolerated after 10 years of use.(Gynecology)

SEATTLE -- Increases in bone mineral density tend to plateau after 5 years of alendronate treatment for osteoporosis, but bone density loss rapidly resumes following cessation of the bisphosphonate, according to the findings of an extension trial that looked at 10 years of continuous therapy.

There's also little indication that long-term treatment is associated with adverse effects or events, the study's principal investigator, Dennis Black, Ph.D., said at the annual meeting of the American Society for Bone and Mineral Research.

"Continued use of alendronate for 10 years is safe and well tolerated," said Dr. Black, a professor of epidemiology and biostatistics at the University of California, San Francisco.

The study reported by Dr. Black was an extension of a 15-center investigation known as the Fracture Intervention Trial (FIT). In the extension, subjects who had received alendronate during FIT, for an average 5 years, were randomized to either alendronate, 5 mg or 10 mg per day, or to placebo for an additional 5 years.

The extension phase of the investigation enrolled and evaluated 1,099 subjects, all of whom were osteoporotic at the start of the initial study; 70% of those participants were still taking their assigned pills at the end of this second 5-year period.

During the initial trial, total-hip bone mineral density (BMD) was increased by an average of 4% in the alendronate group, Dr. Black said.

Total-hip BMD declined an average of 1% in the alendronate groups in the second 5-year period but remained better than that of patients who switched to placebo. All told, by the end of the 10-year period, patients treated with alendronate had an average total-hip BMD that was still 2.8% greater than for those switched to placebo.