BRAND NAME: AREDIA
When we think of our skeletons we commonly imagine a structure made of white bones that serves as a supportive structure to our softer tissues. It is easy to forget that living bone is an active tissue that grows, remodels, heals, and requires blood flow. Its marrow (pulpy portion in its central cavities) serves as the source of our blood cells. The bone itself stores and releases calcium and phosphorus which our soft tissues need for proper muscle contraction and metabolism. As we exercise and create greater demand on our muscles, our bones must change as well to strengthen and offer greater support.
New bone is constantly being laid down by cells called osteophytes and old bone is constantly being removed and reshaped by cells called osteoclasts. In the course of removing bone, the osteoclasts free up calcium for the circulation and are part of the complex hormonal system we use to regulate our blood calcium. The bisphosphonates are a class of medications which are inhibitory on the osteoclasts causing them to be less enthusiastic in their bone removal process or even killing them. There are several situations where it might be a good idea to interfere with the removal of old bone:
Research on bisphosphonates is on-going. There is some thought that they actually kill tumor cells directly and inhibit tumor spread. Pamidronate is one of the most commonly used bisphosphonates in veterinary medicine.
HOW THIS MEDICATION IS USED
This medication is given as an intravenous infusion, meaning it is mixed in a large volume of fluid and given over several hours through a vein. When used to palliate bone tumor pain such infusions are given every 3-6 weeks.
Pamidronate has the potential to cause damage to the kidneys which is why it is given as an infusion in a large amount of fluids. At least two hours of infusion seems to be adequate to prevent kidney problems but periodic monitoring of kidney related lab tests is a good idea if this medication is to be repeatedly used.
In humans bone marrow problems have been reported in conjunction with pamidronate use (reduction in red blood cells, platelets or increased granulocytes).
Electrolyte imbalances may occur with pamidronate use.
Lab tests relevant to all the above issues are easily monitored. You may wish to discuss a regular testing protocol with your veterinarian if regular pamidronate infusions are planned.
Pamidronate overdose could manifest with a low blood calcium level. Twitching, anxiety, muscle weakness or seizures could result.
INTERACTIONS WITH OTHER MEDICATIONS
Monitoring tests become extra important when pamidronate is used with medications that influence blood calcium levels or with drugs for which kidney toxicity is a concern. Other drugs that might come to be used in the same situations where pamidronate is used might include:
CONCERNS AND CAUTIONS
Pamidronate may be a problem for patients with kidney insufficiency. Kidney function should be monitored if bisphophonates are regularly used (see above).
Pamidronate should not be used in pregnant or nursing patients.
Page posted: 4/18/2011