Biphosphonate

Biphosphonates are a class of drugs used to treat diseases involving bone loss, typically osteoporosis. They can also be injected Intravenously to treat certain types of cancer. They work by mimicking other body chemicals that inhibit the action of certain enzymes involved in bone loss. 
The most common side effects are inflammation of the stomach and esophagus, although these can be avoided if the patient remains in an upright posture (sitting or standing) for at least one hour after taking the drug. They should be avoided if the patient has had recent dental work (as they tend to migrate to the site of the missing tooth) or if the patient develops bone, muscle or joint pain.
Biphosphonate at Wikipedia