All of these processes by which steroids cause increased bone resorption are exacerbated by chronic renal failure. All bisphosphonates exert their therapeutic effect by inhibiting bone resorption. They bind preferentially to bones with high turnover rates, such as trabecular bone. By decreasing resorption, the number of new bone remodeling units is decreased and the depth of the resorption sites is reduced. The mechanism of action of bisphosphonates in inhibiting bone resorption is through direct and indirect effects on osteoclasts.
Osteoclast activity is directly inhibited and the number of osteoclasts is reduced.
Fewer osteoclasts are recruited to bone remodeling sites and differentiation of osteoclast precursors is impaired. Corticosteroids reduce bone mass preferentially in trabecular bone and to a great degree by enhancing bone resorption. For this reason bisphosphonates, by their inherent mechanism of action, are theoretically suitable agents to treat and prevent corticosteroid induced osteoporosis. The safety of these agents has been substantiated. Bisphosphonates are also useful in the prevention of steroid induced osteoporosis.