Bisphosphonates are drugs that inhibit bone turnover by decreasing the resorption of bone. They do this both directly, by inhibiting the recruitment and function of osteoclasts (the bone-resorbing cells), and indirectly, by stimulating osteoblasts (the bone-forming cells), to produce an inhibitor of osteoclast formation. Bisphosphonates may also shorten the life span of osteoclasts. The bisphosphonate compounds available in at least one country include etidronate, clodronate, pamidronate, tiludronate, alendronate, and ibandronate. Although these compounds differ markedly in potency, they share common properties: they are poorly absorbed from the gastrointestinal tract and are concentrated in bone, where they remain until the bone . . .