Osteoporosis is a condition in which the bones become thin or brittle, and therefore break more easily. It is a condition most commonly found in the elderly. Bones are living tissue that is constantly being regenerated. Osteoclasts are bone cells that break down bone tissue and release the bone minerals into the blood stream. Osteoblasts are bone cells that build up new bone tissue. When these two processes are in balance, the bones remain healthy and strong. When bone breakdown outpaces the buildup of bone, osteoporosis occurs.
Bisphosphonates
Bisphosphonates have been the most common treatment for osteoporosis since the release of Fosamax in 1995. Researchers do not understand exactly how bisphosphonates increase bone density, but they believe they may block an enzyme that keeps osteoclast cells alive.
Fosamax, Actonel, Boniva and Reclast are bisphosphonates. These drugs are not aborbed very well, so they must be taken on an empty stomach. Since they can irritate the esophagus, you must remain upright for 30 minutes after taking them.
Estrogen Replacement Therapy
Estrogen replacement therapy (ERT) was at one time the mainstay of osteoporosis treatment, until studies showed a link between ERT and heart attack and stroke.
Estrogen can slow the rapid bone loss that occurs after menopause. Researchers believe estrogen blunts the affect of parathyroid hormone, which regulates the amount of calcium in the blood. In the bones, parathyroid hormone stimulates the osteoclasts, which then release the bone minerals into the bloodstream by breaking down bone tissue.
Selective Estrogen Receptor Modifiers
Selective Estrogen Receptor Modifiers stimulate the estrogen receptors in bones. This means that they imitate the effect of estrogen in these tissues. Raloxifene, a SERM sold under the brand name Evista, protects against fractures in the spine, but not the hips.
Calcitonin
Calcitonin is a hormone released by the thyroid gland. It reduces calcium levels in the blood. Synthetic calcitonin comes in injectable form or as a nasal spray called Miacalcin. In the bones, calcitonin halts the action of osteoclasts. Calcitonin appears to exert the most effect in the spine.
Teriparatide
Teriparatide, sold under the brand name Forteo, was approved for osteoporosis in 2002. It is a synthetic form of parathyroid hormone. Although constant high levels of parathyroid hormone eventually lead to bone loss, the small, intermittent doses given in teriparatide stimulate the buildup of bone mass. Teriperitide is given as a subcutaneous injection. Like the bisphosphonates, Forteo decreases the risk of fractures in both the hips and the spine.
References
- Basic and Clinical Pharmacology; Bertram Katzung; 2007
- U.S. Pharmacist - Osteoporosis: A Preventable Part of Aging
