Denosumab (Prolia) mimics the natural process that keeps OsteoClasts (the cells that gobble up bone) under control before menopause. OsteoCytes release Osteoprotegrin (OPG) when Estrogen (or Testosterone) is on board. OPG controls the formation and activation of OsteoClasts by blocking RANK-Ligand, which is necessary for OsteoClast formation and activation. This decreases fracture risk.
Prolia mimics OPG and blocks RANK-Ligand, thus blocking bone resorption by preventing OsteoClasts. It is a RANK-Ligand Antibody. It is like birth control for OsteoClasts. Prolia is given as a shot under the skin twice a year. Prolia is very effective at first, but begins to fade by 6 months. Without another injection , Prolia has totally lost effectiveness by 12 months after the last shot.
Prolia does not accumulate in bone like the Bisphosphonates. There is no “Drug Holiday” possible. Reclast and other Bisphosphonates persist in bone for many years with gradually decreasing effectiveness. Prolia is totally gone in 12 months. This can be a problem if the patient forgets to continue treatment for osteoporosis.
Prolia is metabolized by the liver, so there is no concern about kidney function, as there is with Reclast. For older individuals with tired kidneys, Prolia offers a great advantage.
Heartburn, reflux disease, GERD, IBS and other Gastro-Intestinal issues can be a problem with oral bisphosphonates. Prolia has no GI issues at all.
Prolia restores control over OsteoClast formation and action. This is important in Androgen Deprovation Therapy for Prostate Cancer, which we already discussed. It is also important when using Aromatase Inhibitors for Breast Cancer. More about that next time.
Take Control of your bones.
Jay Ginther, MD