Alendronate, the drug most commonly used to treat osteoporosis, is safe and effective for the prevention of fractures and bone loss for as long as 10 years, according to results published by the Alendronate Phase III Osteoporosis Treatment Study Group involving 247 postmenopausal women.
Compared with baseline values, the study reported that 10 mg a day of alendronate given over 10 years produced mean increases in bone mineral density of 13.7% at the lumbar spine, 10.3% at the trochanter, 5.4% at the femoral neck, and 6.7% at the total proximal femur. Smaller gains occurred with 5 mg daily. The drug only gradually lost its effects when discontinued.
Critics of the current study say that it is still unclear whether women need to take alendronate for such a long period of time or when they should start. Some experts recommend a 1-, 2-, or 3-year break from the drug after 5 years of continuous use. And while previous shorter studies have reported that alendronate can halve the risk of fracture, the current study used bone density measurements, not fractures, as an endpoint. High bone density isn't a guarantee against fractures.
Bone HG, Hosking D, Devogelaer JP, et al. Ten years' experience with alendronate for osteoporosis in postmenopausal women. N Engl J Med. 2004;350:1189-1199.