- In the U.S. today, 10 million individuals already have osteoporosis and 18 million more have low bone mass, placing them at increased risk for the disease.
- Osteoporosis is responsible for more than 1.5 million fractures annually, including 300,000 hip fractures, and approximately 700,000 vertebral fractures, 250,000 wrist fractures, and more than 300,000 fractures at other sites.
- It is estimated that approximately one out of two women and one out of eight men over 50 will sustain one or more osteoporosis-related fractures of the spine, hip, or wrist during their remaining lifetimes.
- Effective treatments are available to prevent osteoporosis and reduce the risk of debilitating fractures.
Percentage of Females Age 65 or Older who have Osteoporosis, by Race/Ethnicity
Source: 1998 Medicare Current Beneficiary Survey
Osteoporosis is a major public health threat for 28 million Americans, 80 percent of whom are women. (NIH 2002) Osteoporosis is characterized by low bone mass that leads to an increased risk of fracture, most frequently of the spine, hip, or wrist. Osteoporosis occurs in both men and women but is most common in post-menopausal women. Osteoporotic hip fractures, in particular, are associated with substantial morbidity, disability, and mortality. Moreover, only one-third of hip fracture patients will return to pre-fracture independence. (U. of Washington 2002) Estimated national direct expenditures (hospitals and nursing homes) for osteoporosis and related fractures are about $14 billion a year.
Treatment of osteoporosis
Osteoporosis is largely a preventable and treatable disease. Comprehensive treatment programs that focus on proper nutrition, exercise, medication, and prevention of falls, can slow or stop bone loss, increase bone density, and reduce fracture risk. (NIH 2002) First introduced in the mid-1990s, bisphosphonates, which inhibit bone reabsorption, represent one recent category of pharmaceuticals that effectively treat osteoporosis. (National Osteoporosis Foundation 2002) Alendronate and risedronate are in this category of drugs. In one study, risedronate significantly reduced the risk of hip fractures in elderly women with a confirmed diagnosis of osteoporosis. (McClung 2001)
Although treatment with these agents significantly reduces the risk of developing osteoporosis and subsequent fractures, some countries restrict reimbursement for these drugs to relatively narrow categories of patients. For example, in New Zealand, only specialists can initiate therapy with Fosamax®, a bisphosphonate, and then only after the patient has already suffered one previous, significant osteoporotic fracture (radiologically demonstrated) and has a substantially low bone mass density. (Merck & Co. 2002) Australia, Italy, Belgium, and France have similar restrictions on reimbursement for Fosamax®. In Ontario, Canada, Fosamax® is only reimbursed for treatment of osteoporosis in post-menopausal women who have failed to respond to etidronate (which is not even a mainstream treatment in the U.S. for osteoporosis), as evidenced by continued loss of bone mineral density after two years of treatment, a new fracture after one year of etidronate therapy, or intractable side effects or allergic reaction from etidronate. (Merck & Co. 2002)
Drugs in the pipeline for osteoporosis
- Selective Estrogen Receptor Modulators (SERMS) mimic the effects of estrogen and prevent bone loss. (Ettinger 1999)
- Novel approaches for new drugs to treat osteoporosis target different elements in bone reabsorption and formation. (NIH 2002)
- Phytoestrogens are in clinical trials. (NIH 2002)
A number of potentially very exciting agents are being developed for the treatment of osteoporosis. Some of these may have fewer side effects and, therefore, may be better tolerated by patients. Fifteen drugs were in clinical trials for osteoporosis in 2002. (PhRMA 2002)
These agents can be divided into two categories: those that prevent bone reabsorption and those that promote new bone formation. Different elements involved in maintaining healthy bone are targeted by these new compounds, including factors involved in bone cell function and regulation, cell membrane receptors and attachment proteins, and cellular enzymes and nuclear transcription factors. (Tobias 2002; Boskey 2001)
For example, a new class of drugs called Selective Estrogen Receptor Modulators (SERMS) prevents bone loss and reduces the risk of fractures, by mimicking the effects of estrogen in some parts of the body. (National Osteoporosis Foundation 2002) Raloxifene is one of the first SERMS available.
Both Ontario and Quebec, Canada, limit coverage for raloxifene. Ontario’s formulary approves raloxifene treatment only for postmenopausal women who have failed to respond to etidronate (as evidenced by continued loss of bone mineral density after two years of therapy), have experienced a new osteoporosis related fracture after one year of etidronate treatment, or have experienced intractable side effects or allergy with etidronate which precludes continuation of therapy. (Ontario Ministry of Health and Long Term Care 2002) In Quebec, raloxifene treatment is not listed as an approved therapy on Quebec’s formulary. (Quebec Prescription Drug Insurance Plan 2002)
In the near future, other agents may be available to treat osteoporosis. Phytoestrogens, substances derived from soy, are being tested to determine if they can reduce bone loss in older women. Many women are electing to try “natural” estrogens because these products are readily available and seem to work as selective estrogen receptor modulators. That is, they stimulate estrogen receptors on bone and slow bone breakdown, but have tissue selectivity that maximizes benefits and depresses harmful side effects. (NIH 2002)
Nitroglycerine is a drug used to treat angina pectoris (a recurring pain or discomfort in the chest that happens when some part of the heart does not receive enough blood) that has been shown in pilot studies to reduce bone loss in women who have had their ovaries removed. (NIH 2002) Nitroglycerin releases a substance (nitric oxide) that is a powerful mediator of hormone action. It is being tested in postmenopausal women, but if found to be effective could work equally well in men.