Osteoporosis in Postmenopausal Women

Anna Leyzerenok, PharmD, and David Q. Pham, PharmD, BCPS
Published Online: Thursday, June 1, 2006

Osteoporosis is a bone disorder in which bone mass in the body decreases, thus causing bones to become weakened to the extent that minimal trauma may cause fractures.1 It is believed that calcium and estrogen are major factors in the building and maintaining of bone strength in women.2 Studies show that postmenopausal women have a higher frequency of osteoporosis due to the rapid loss of calcium from the bones and the lower levels of estrogen in the blood.2

Prevalence

According to the American Medical Women's Association, osteoporosis is a common disease state affecting approximately 29 million people in the United States.3 In women, it is believed that bone mass declines gradually after age 30 and that this decrease progresses markedly at menopause. In fact, it is estimated that 13% to 18% of women in the United States who are at least 50 years old have osteoporosis, and an additional 37% to 50% have osteopenia, which is the presence of less than the normal amount of bone mass.4,5 This is an important finding, because osteoporosis causes 1 million fractures yearly, and the mortality rate following a hip fracture is 12% to 20%.3 For postmenopausal women, hip fracture is the second leading cause of admission to nursing homes and is one of the major disorders that contribute to the loss of independence and quality of life.3

Risk Factors

Risk factors for osteoporosis include a family history of osteoporosis or fracture in a first-degree relative, low body weight, a history of bone fracture as an adult, current cigarette smoking, Caucasian race, poor nutrition, alcoholism, early menopause, long-term low calcium intake, and inadequate physical activity.3

Diagnosis

Women who are postmenopausal and at least 65 years of age, women who are younger than 65 years of age but have at least one risk factor for osteoporosis, and women who are postmenopausal with fractures should make an appointment to visit their primary care provider to see whether they suffer from osteoporosis.4

Pharmacologic Treatment

Osteoporosis may be prevented and treated with several medications. The most common medications include calcium and vitamin D, bisphosphonates, selective estrogen receptor modulators (SERMs), calcitonin-salmon, teriparatide, and hormone replacement therapy.

Calcium and Vitamin D

Calcium intake can prevent and/or reduce bone loss in adults. There are different calcium salts, such as carbonate, citrate, and lactate. Calcium carbonate should be ingested with food to increase calcium absorption.6 Calcium citrate is easily absorbed, has few side effects, and does not need to be taken with food.6 Patients should take 500 to 600 mg of calcium carbonate or 200 to 315 mg of calcium citrate per day. Vitamin D should be taken at a dose of 400 international units per day to ensure optimal calcium absorption.6 Different combinations of calcium and vitamin D are available.

Bisphosphonates

This class includes such medications as alendronate (Fosamax), risedronate (Actonel), and ibandronate (Boniva). They are used to prevent and/or treat osteoporosis. Bisphosphonates increase bone density by reducing bone loss mainly at the spine and hip.

Side effects include upset stomach and headache. Bisphosphonates may be taken daily, weekly, or monthly. To avoid developing long-term stomach irritation, it is very important for the patient to take these medications with 6 to 8 oz of plain water on getting up in the morning, and more than 30 minutes before ingesting the first food, beverage, or other medication. After taking this medication, the patient should stay in an upright position (not lying down) for at least 30 minutes. It also is necessary to have adequate calcium and vitamin D intake while taking a bisphosphonate.6

SERMs

Raloxifene (Evista) is the only FDA-approved drug from the SERM class. SERMs work as a natural hormone on estrogen receptors on bones to decrease bone loss. This class of medications does not affect breast and uterine tissue, thus eliminating several side effects. In one study, raloxifene increased bone mineral density in the spine and femoral neck and reduced risk of vertebral fractures.7 Side effects, however,may include hot flashes, joint pain, and possible risk for deep vein thrombosis.6 A SERM is a good alternative for women who cannot tolerate estrogen.

Calcitonin-salmon (Miacalcin)

Calcitonin-salmon blocks the effect of natural calcitonin in the body and prevents bone loss. It is used for osteoporosis treatment for women at least 5 years postmenopausal.6 It is less effective than other osteoporosis medications. Thus, it is used more frequently for patients with fracture pain or for patients who cannot use other osteoporosis medications for different reasons. It has been shown to reduce the risk of spinal fractures.

Teriparatide (Forteo)

Teriparatide is a parathyroid hormone analogue. It is used once daily to stimulate the building of bone mass by increasing calcium absorption in the gut. Treatment with teriparatide will increase bone mineral density, bone mass, and bone strength.

Hormonal Therapy (HT)

Estrogen replacement therapy increases bone density. HT relieves menopausal symptoms such as hot flashes, vaginal dryness, and night sweats. Some studies indicate that HT can increase bone density by 5% in 2 years.8 The use of HT is approved for the prevention but not for the treatment of osteoporosis. The decision to use HT should be based on the patient's risk factors, because this therapy has several unwanted side effects. It also should be remembered that bone loss will resume once HT is stopped.

Nonpharmacologic Treatment

Women, especially postmenopausal women, can prevent or reduce their risk of developing osteoporosis by taking calcium daily and exercising appropriately. Appropriate exercise includes at least half an hour of weight-bearing exercise, such as jogging, walking, stair climbing, dancing, tennis, or weight lifting. It is recommended that these exercise activities be done at least twice weekly and for 40 minutes each time. Avoiding cigarette smoking and alcohol intake will help reduce risk.6 Studies also show that 15 to 20 minutes of sunlight exposure daily will help maximize the absorption of calcium.

Summary

Osteoporosis is common among postmenopausal women. Taking appropriate measures to avoid risk factors such as cigarette smoking and alcohol intake may be helpful. Medications such as calcium, vitamin D, bisphosphonates, SERMs, calcitonin-salmon, teriparatide, and hormone replacement therapy have been shown to be beneficial. Patients should be advised to check with their doctor before taking any medication.

Dr. Leyzerenok received her PharmD degree from the Arnold & Marie Schwartz College of Pharmacy and Health Sciences, Long Island University, in May 2006. Dr. Pham is an assistant professor of pharmacy practice at that institution. At the time the article was written, Dr. Pham was Ms. Leyzerenok's preceptor for internal medicine clinical rotations.

For a list of references, send a stamped, self-addressed envelope to: References Department, Attn. A. Stahl, Pharmacy Times, 241 Forsgate Drive, Jamesburg, NJ 08831; or send an e-mail request to: astahl@ascendmedia.com.




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