Pamidronate is used to treat high levels of calcium in the blood that may be caused by certain types of cancer. Pamidronate is also used along with cancer chemotherapy to treat bone damage caused by multiple myeloma (cancer that begins in the plasma cells [a type of white blood cell that produces substances needed to fight infection]) or by breast cancer that has spread to the bones. Pamidronate is also used to treat Paget's disease (a condition in which the bones are soft and weak and may be deformed, painful, or easily broken). Pamidronate injection is in a class of medications called bisphosphonates. It works by slowing bone breakdown, increasing bone density (thickness) and decreasing the amount of calcium released from the bones into the blood.