Current bone mineral density data on bisphosphonates in postmenopausal osteoporosis.

Osteoporosis is a disorder of skeletal fragility characterized by an imbalance in bone turnover such that bone resorption exceeds bone formation. Accelerated bone resorption is the principal physiological derangement responsible for both postmenopausal and age-related bone loss. Furthermore, increased bone turnover is itself a risk factor for fracture, independent of bone mineral density. Thus, there is a strong rationale for the use of potent antiresorptive drugs for the treatment of postmenopausal osteoporosis. Bisphosphonates are a class of drugs that inhibit osteoclast activity and bone resorption. Recent studies with etidronate, pamidronate, and alendronate demonstrate the ability of these drugs to suppress bone turnover and to preserve or increase bone mass. In large studies with alendronate, in long-term studies with clodronate, and in patients at high fracture risk treated with etidronate, decreased fracture occurrence is observed. Except for upper gastrointestinal intolerance with aminobisphosphonates, these drugs are very well tolerated. Bisphosphonates are promising alternatives to estrogen for the treatment of patients with decreased bone mass and, particularly, those with severe osteoporosis. Further studies are needed to define the optimal long-term dosing regimen and to establish whether more potent members of this drug class are more effective or can be administered by different routes. The effectiveness of bisphosphonates in combination with estrogen or bone growth stimulators also requires evaluation, and the extended long-term safety of these drugs must be determined.