If you learn that you have osteoporosis and are at high risk for fracture, there are medications available that are very effective at reducing risk. Until recently, hormone therapy was widely recommended as a means to prevent osteoporosis. But the available alternatives to hormone therapy are equally effective at maintaining bone density and carry less risk. These include:
Bisphosphonates
Drugs called bisphosphonates, such as alendronate (brand name Fosamax), risedronate (brand name Actonel), and ibandronate (brand name Boniva), are one treatment option. These drugs act by binding to the osteoclasts (the cells that resorb bone), preventing them from functioning. This decreases bone loss in postmenopausal women. These drugs decrease bone loss, but that doesn't mean they actually build bone or stimulate the growth of new bone. Rather, these drugs increase bone density by filling in the spaces that have been left empty by the osteoclasts (the resorbers) and not filled in by the osteoblasts (the builders).
We know that the bisphosphonates decrease fractures in the short term, but we don't know what they do in the long term. In 2012, the FDA released a study investigating the effects of bisphosphonates over three to five years. The study, which looked at three long-term extension trials related to bisphosphonates and osteoporosis, found taking bisphosphonates for five or more years results in “maintenance of bone mineral density in the femoral neck and increases in bone mineral density at the lumbar spine.” After five years, bone mineral density in the femoral neck decreases modestly for one to two years and then stabilizes, while density in the lumbar spine continues to increase without the medication. The duration of treatment in each of the studies lasted from six to 10 years but no optimal duration of use was determined.
Because they interfere with the balance between resorption and buildup, bisphosphonates may eventually affect the architecture of the skeleton. This does not mean that they aren’t good drugs. But it does indicate that they should be saved for women who have osteoporosis or who have had a fracture, rather than being given as prevention.
Note to Women with Breast Cancer:
Many women with hormone-sensitive tumors are now taking an aromatase inhibitor as part of their breast cancer treatment. These drugs—anastrozole (brand name Arimidex), letrozole (brand name Femara), and exemestane (brand name Aromasin)—work by blocking aromatase, the enzyme that converts androgens into estrogen. Clinical trials have found that these drugs, unlike the hormone therapy tamoxifen, increase bone fracture risk.
For women who have osteoporosis and are on aromatase inhibitors, bisphosphonates should help reduce fracture risk. For women with osteopenia, though, it still makes more sense to wait until osteopenia has advanced to osteoporosis to begin taking these drugs. The exception would be a woman who is starting on an aromatase inhibitor and is already close to a –2.5 on her dual-energy X-ray absorptiometry (DEXA) scan. In this case, she may want to start on a bisphosphonate while starting on the aromatase inhibitor.
Bisphosphonates are also used to treat bone metastases and hypercalcemia, a condition when the breakdown of bone leads to excessive calcium in the blood, in women with breast cancer. A 2015 meta-analysis by the Early Breast Cancer Trialists' Collaborative Group (EBCTCG) found that bisphosphonates have profound effects on bone physiology and can modify the metastasis process, preventing approximately one in six breast cancer deaths in postmenopausal women over the course of a decade.
Raloxifene
A second option is raloxifene (brand name Evista). Raloxifene is a selective estrogen receptor modulator. This means it acts like an estrogen in some organs—such as the bones, to maintain bone density—and blocks it in others, such as the breast and the uterus. It does not increase the risk of heart attacks like estrogen does or increase the risk of uterine cancer, like the breast cancer drug tamoxifen.
Raloxifene is slightly less effective than the bisphosphonates, and because it blocks estrogen one of its common side effects is hot flashes. In May 2006, findings from the STAR trial were released which showed that raloxifene, like tamoxifen, decreases breast cancer risk. This means raloxifene could be a good choice to treat osteoporosis in women who are at high risk for breast cancer.
Calcitonin
A third option is calcitonin (brand names Calcimar and Micalcin). Calcitonin is a hormone produced by the thyroid gland that inhibits bone breakdown. By inhibiting bone removal by the osteoclasts and promoting bone formation by the osteoblasts, it can increase bone density in women with osteoporosis.
In two-year studies conducted in women with osteoporosis, calcitonin was found to increase bone density by 5% when taken with calcium; in comparison, women who were given calcium and a placebo had a 2% decrease in bone density. One of the more dramatic effects of calcitonin is the decrease of pain caused by vertebral fractures from osteoporosis. This alone may make it a good choice for certain situations. It comes in an injectable form and as a nasal spray. It is advised that women taking calcitonin also take adequate amounts of calcium and vitamin D.
Teriparatide
Teriparatide (brand name Forteo), a form of human parathyroid hormone, which does build new bone in women with osteoporosis, was approved by the FDAM in 2002 for the treatment of osteoporosis in postmenopausal women who are at high risk for fractures. It is administered by injection once a day in the thigh or abdomen. It has been found to increase the risk of osteosarcoma, a rare but serious cancer of the bone in rats, and it's not known if there is a higher risk of bone tumor in humans. A 2011 study found the risk of osteosarcoma is “extremely rare” at approximately 1 in 100,000 people.
Note to Women with Breast Cancer:
Women who have bone cancer, breast cancer that has spread to the bones, or hypocalcemia should not use teriparatide.