Osteoporosis is a disease characterized by deterioration of bone tissue and low bone mass, resulting in fragile bones. It affects approximately 10 million Americans, with over 34 million others at risk of developing the disease, according to statistics reported by the National Osteoporosis Foundation. Bones are living tissue that is continually broken down and reabsorbed as new bone tissue is formed. Osteoporosis occurs when there's an imbalance between the amount of bone reabsorbed into the body and the new bone formed. Several different types of medications help slow or stop osteoporosis. Some act on the bone resorption phase; others support the formation of new bone.
Bisphosphonates
Bisphosphonates are a class of drugs that work by inhibiting the breakdown of bone tissue. There are two main types of cells in the bones. Osteoclasts are responsible for breaking down bones, and osteoblasts build up bone. Bisphosphonates inhibit the function of the osteoclasts while allowing the osteoblasts to function properly. This results in less bone tissue breaking down while the same amount remains to be formed, resulting in an increase in bone mass.
Several different bisphosphonate drugs are approved by the Food and Drug Administration (FDA) for treating osteoporosis, including alendronate, ibandronate, risedronate and zoledronic acid. In general, these medications are taken orally either once a week or once a month, depending on the medication. Side effects of bisphosphonate drugs include nausea, difficulty swallowing and abdominal pain.
Selective Estrogen Receptor Modulators (SERMs)
Selective estrogen receptor modulators--also known as estrogen agonists/antagonists--work in a similar way to estrogen therapy (also called hormone therapy) but without the unwanted side effects, according to the Mayo Clinic. The female hormone estrogen is an important factor in maintaining the balance between the functions of the osteoclasts and osteoblasts. When estrogen levels drop, such as during menopause, the function of the osteoclasts is enhanced while the body's ability to absorb calcium, which is needed for the osteoblasts to form new bone, is decreased.
Taking estrogen supplements can help to alleviate osteoporosis. However, there are many potentially dangerous side effects to hormone therapy, including an increased risk for uterine or breast cancer, blood clots, heart attacks and stroke. SERMs, such as raloxifene, were developed to provide the same advantages of estrogen with infrequent side effects of hot flashes, leg cramps and blood clots.
Calcitonin
Calcitonin is a naturally occurring hormone that's responsible for regulating calcium absorption and the rate of bone loss and formation. Taking calcitonin can help slow the breakdown of bone, resulting in an increase in bone mass.
Teriparatide
Teriparatide is a synthetic (chemically formulated) version of a hormone produced by the parathyroid gland. Teriparatide is different from the other drugs used to treat osteoporosis because instead of inhibiting the osteoclast function, it triggers the osteoblasts to boost the rate of new bone formation. In addition, teriparatide increases the absorption of calcium, which is necessary for the osteoblasts to form new bone tissue.
