Effect of Bisphosphonate on Osteoclast of Bone

Bisphosphonates are synthetic analogues of naturally occurring pyrophosphate molecule and are potent inhibitors of osteoclastic bone resorption. Bisphosphonates bind to hydroxyapatite crystals with high affinity and after incorporation by osteoclasts, the primary target cell, it inhibits osteoclastic bone resorption. The anti-resorptive effect has been shown to occur in organ culture as well as in-vivo, but the precise mechanism by which it exerts its bone resorbing effect is not yet fully understood. In vitro and in vivo studies have demonstrated that zoledronate is a more potent inhibitor of osteoclasts than earlier bisphosphonates. Bisphosphonates have now emerged as a leading therapeutic agent for the treatment of hypercalcaemia of malignancy, bone metabolic diseases, Paget’s disease and postmenopausal osteoporosis.