[New development in bisphosphonate treatment. When and how long should patients take bisphosphonates for osteoporosis?].

Bisphosphonates such as alendronate and risedronate effectively reduce hip fracture risk, and thus are suitable for the elderly people in whom this fracture is most likely to happen. Bisphophonates should be administered when patients meet the guideline made by Japanese bone society, which picks up prevalent fractures, low bone mineral density, and established risk factors as features for starting osteoporosis treatment. Long-term alendronate administration may inhibit normal repair of microdamage arising from severe suppression of bone turnover (SSBT), which, in turn, results in accumulation of microdamage. This process would lead to brittle bone and the occurrence of unexpected stress fractures, characteristically at the subtrochanter of femur. A large-scale study suggests that for more women, discontinuation of alendronate after 5 years for up to 5 more years does not significantly increase fracture risk. Thus, alendronate treatment might be stopped for a while after 5 years to prevent SSBT and subsequent stress fractures.