Bisphosphonates: mechanisms of action and clinical use in osteoporosis--an update.

Bisphosphonates are a new class of compounds with the ability to decrease bone resorption. Their mode of action appears to be complex, involving both a direct effect on the osteoclasts and an indirect one through osteoblasts. They are currently the drugs of choice in humans for Paget's disease and tumor bone disease, and are most useful in various types of osteoporosis. In view of their low toxicity, they are a most valuable addition to our therapeutic possibilities in the treatment of bone diseases.