Bisphosphonates

What are Bisphosphonates?

Bisphosphonates are a group of medicines that slow down or prevent bone loss, strengthening bones. Bisphosphonates inhibit osteoclasts which are responsible for breaking down and reabsorbing minerals such as calcium from bone (the process is known as bone resorption). Bisphosphonates allow osteoblasts (bone building cells) to work more effectively, improving bone mass.

Bisphosphonates are used in the treatment of osteoporosis, Paget’s disease of bone, and may be used to lower high calcium levels in people with cancer.

When used to treat osteoporosis, the optimal duration of treatment is not yet known; however, the majority of benefits appear to happen within the first five years of treatment and long-term use has been associated with atypical femur fractures, osteonecrosis of the jaw and esophageal cancer. Experts recommend the need for bisphosphonate treatment should be reviewed every three to five years.

Bisphosponates such as risedronate (Actonel), alendronate (Fosamax), ibandronate (Boniva), zoledronic acid (Reclast), and pamidronate (Aredia) are used to treat and prevent osteoporosis—or, bone thinning—which occurs when the bones lose calcium and other minerals that help keep them strong and compact.

Mechanism of action — The bisphosphonates inhibit osteoclastic bone resorption via a mechanism that differs from that of other antiresorptive agents [2-4]. Bisphosphonates attach to hydroxyapatite binding sites on bony surfaces, especially surfaces undergoing active resorption.