Bone constantly undergoes a cycle of losing old cells and regrowing new ones. When growth slows or resorption of old bone cells speeds up, bones lose mass and osteoporosis can result. Menopause, aging and poor nutrition can all affect this process and lead to a loss of bone mass. Medications that treat osteoporosis work by altering this cycle, either by slowing the resorption of bone by the body or by helping the body grow new bone tissue.
Bisphosphonates
Bisphosphonates are considered antiresorptive medications: drugs that prevent or slow the resorption of old bone cells. People taking bisphosphonates lose less bone but continue to build bone, which gradually increases bone density. Bisphosphonates include alendronate sodium, which goes by the brand name Fosamax; ibandronate sodium under the brand name Boniva; risedronate sodium under the brand name Actonel; and zoledronic acid, which has the brand name Reclast. All of the bisphosphonates are used to treat postmenopausal women and all but ibandronate are approved by the FDA for the treatment of men with osteoporosis. Some bisphosphonates also include calcium or vitamin D supplements. Since bisphosphonates stay in bones for a long time, their beneficial effects often continue for years after a patient stops taking them. Oral bisphosphonates can have side effects, which include stomach upset, esophageal and gastric ulcers, difficulty swallowing, osteonecrosis of the jaw, irregular heartbeats and problems with vision. Bisphosphonates given as an infusion may produce flu-like side effects, headaches and sore muscles or joints.
Calcitonin
Calcitonin is another antiresorptive. It comes in an injectable form or as a nasal spray and goes by the brand names Fortical and Miacalcin. Calcitonin is actually a hormone that naturally occurs in the body, where it regulates bone metabolism and calcium levels in bone. Calcitonin is used to treat women who are five years or more past menopause. Flushed face and hands, frequent urination, nausea, and skin rash are all side effects of injectable calcitonin. It is also available in nasal spray form, the side effects of which are nasal irritation, nosebleeds and headache.
Raloxifene
Raloxifene is a selective estrogen receptor modulator (SERM), a kind of drug that mimics estrogen activity. Since estrogen naturally maintains bone density in the body, raloxifene has the same effect. It is sometimes used in place of estrogen or hormone therapy. Hot flashes, leg cramps and blood clots have been reported as side effects. Raloxifene is designed for use in postmenopausal women.
Estrogen Therapy and Hormone Therapy
Postmenopausal women also have the option of trying estrogen therapy or hormone therapy, which uses a combination of estrogen and progesterone. Estrogen has a protective effect on bone and when estrogen production drops after menopause, bones loses this protection. Estrogen and hormone therapy help restore this protection and stem the loss of bone density. Both estrogen therapy and hormone therapy are available as a pill or through a patch. Blood clots, breast tenderness, mood disturbances and vaginal bleeding are potential side effects. These types of medications may also raise the risk of breast cancer, stroke, blood clots and heart attack, so they aren't typically considered a first choice for treatment.
Teriparatide
Teriparatide, a parathyroid hormone, works differently from other osteoporosis medications. Instead of merely slowing bone loss, it also increases the production of new bone. This type of drug is called an anabolic drug and it is given as a daily injection. Teriparatide should only be used for 24 months and then the patient must switch to an antiresorptive drug. Side effects include leg cramps, dizziness and nausea.
