Bisphosphonates Preserve Bone By Slowing Bone Turnover

Bisphosphonates accumulate in your bone.  When OsteoClasts gobble up your bone, bisphosphonates are released into the Osteoclasts and disable or kill the Osteoclasts.  This is great news when the problem is Osteoclasts Gone Wild.  Bisphosphonates preserve bone by slowing down bone resorption.  However, after a few months, bone formation by OsteoBlasts also slows down, resulting in slow bone turnover.

Moderate and balanced bone turnover is good.  You repair microcracks in your bone when OsteoClasts resorb the bone around them and OsteoBlasts fill in the void with new bone matrix.  A mix of new and old bone is far stronger than all old bone.  Some OsteoClast activity is necessary to heal fractures, especially incomplete (stress) fractures.  That is where long term bisphosphonates can be too much of a good thing.

We worry about OsteoNecrosis of the Jaw (ONJ) and Atypical Fractures of the Femur (AFF).  These are very rare conditions which can occur without any medications.  After 8-10 years of bisphosphonates these fractures occur in less than 1 in 1,000 patients.  See the visual post of incidence.  Fracture risk in women and men NOT treated with bisphosphonates or other meds are 500 and 240 times greater.

If you have fractured while on a bisphosphonate, you should stop taking more until the fracture has healed.  Bisphosphonates accumulate best in newly made bone matrix.  Therefore, high amounts can accumulate at the healing fracture site and slow the healing process.  Once the fracture is healed you can resume your medication.

Because bisphosphonates accumulate in bone, we now often offer a “Bisphosphonate Holiday” after 5 years of therapy.  How long you can be on holiday using medication already in your bone varies greatly.  See the post about “Holiday”.

Find out if you need to preserve your bone.  Take action as needed.

Jay Ginther, MD

Categorised in: Medications