(Other name for: alendronate sodium) or A drug used to treat certain bone conditions, such as osteoporosis and Paget disease of the bone. It is also being studied in the treatment of hypercalcemia (high levels of calcium in the blood) and bone pain caused by cancer. Fosamax slows the breakdown of bone and prevents the loss of calcium. It is a type of bisphosphonate. Also called alendronate sodium.