The Dark Side of Fosamax

Bisphosphonates are analogues of pyrophosphate and are incorporated into the crystalline structure of bone.  When osteoclasts reabsorb bone, as part of their continuous job of bone remodeling, the bisphosphonate poisons them and makes them inactive.  If there has been excessive bone reabsorption, as in certain forms of osteoporosis, this may have a short term benefit on bone density, strength, and fracture risk.  This is not the case in all osteoporosis patients, some of whom may have low bone turnover.  This group may actually be harmed by bisphosphonates.  Current screening for osteoporosis uses only bone density measurements, mostly by DEXA, which is not always accurate, and tells nothing of the underlying pathophysiology.  In our experience with chronic kidney disease patients treated with bisphosphonates, all have low turnover when biopsied.

Paralysis of bone remodeling is the likely explanation for late fractures, jaw osteonecrosis, and severe bone pain with fosamax and similar agents.