Bone disorder drugs are medicines used to treat or prevent osteoporosis (brittle bone disease) in women past menopause or in elderly men. They also are prescribed for Paget's disease, a painful condition that weakens and deforms bones, and they are used to control calcium levels in the blood.

Bone is living tissue that is constantly being broken down and replaced with new material. Normally, there is a balance between the breakdown of old bone and its replacement with new bone.

In osteoporosis the bones become porous and thin, weaken, and become more likely to break. Osteoporosis is four times more common in women than in men. Women have less initial bone mass than men, tend to live longer, take in less calcium, and need the female hormone estrogen to keep their bones strong. If men live long enough, they too are at risk of...