Pathogenesis of osteoporosis and challenges for drug delivery.

Bone remodeling is under the control of local factors produced in the bone microenvironment. Many of the mechanisms responsible for coordination of activity between osteoclasts and osteoblasts, and how they are dysregulated in diseases of bone loss such as osteoporosis, are now being clarified. This leads to the possibility that bone remodeling can be manipulated by pharmacological means to reverse the changes caused by common bone diseases. However, many of the potential drugs suffer from non-selectivity in their effects. Targeting of drugs to active skeletal sites is of major interest to the pharmaceutical industry, and there are interesting and exciting possibilities which could lead to more specific therapies for the common diseases of bone loss. These will be reviewed in this chapter.