Bisphosphonates and PTH for Preventing Fractures - Skeletal Aging and Osteoporosis: Biomechanics and Mechanobiology - page 148

Bisphosphonates and PTH for Preventing
Fractures
David B. Burr and Matthew R. Allen
Abstract The risk of fracture is intimately linked to loss of bone mass. The two
most common pharmaceutical agents used to alter this loss are bisphosphonates
and recombinant human parathyroid hormone (rhPTH 1-34; teriparatide). These
two classes of drugs work through distinctly different mechanisms. Bisphos-
phonates bind to bone mineral and inhibit osteoclast activity. This leads to a
reduction in bone remodeling, which slows bone loss, and also leads to signif-
icant changes in the bone material properties such as mineralization, micro-
damage, and the organic matrix. The long-term effects of these altered material
properties are unclear. There are also noteworthy differences among the various
bisphosphonates used clinically such as the speed of onset and magnitude of
remodeling suppression. PTH is an anabolic agent which stimulates both
remodeling and modeling—resulting in the formation of new bone which over
time leads to an increase in bone mass. PTH also alters the material properties
although these changes are distinctly different from the bisphosphonates. Recent
studies have begun to investigate combining bisphosphonates and PTH, either
sequentially or concomitantly, with most data showing that bisphosphonates
D. B. Burr ( & ) M. R. Allen
Department of Anatomy and Cell Biology, Indiana University School of Medicine,
Indianapolis, IN, USA
e-mail: [e-mail]
M. R. Allen
e-mail: [e-mail]
D. B. Burr
Department of Biomedical Engineering,
Indiana University-Purdue University at Indianapolis (IUPUI),
Indianapolis, IN 46077, USA