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Researchers Investigate Once-Yearly Treatment for Osteoporosis as Alternative to Daily Medication


While a variety of drugs exist to help prevent or treat the bone-thinning disease osteoporosis, many people find the regimens or side effects of these medications to be bothersome. In response to this growing trend, researchers are studying whether a yearly infusion of the drug Zometa (generic name, zoledronic acid) is as effective as daily doses of similar drugs such as Actonel (generic name, risedronate sodium), or Fosamax (generic name, alendronate) in preventing or treating osteoporosis. Preliminary results have shown that annual, semi-annual, and quarterly infusions of Zometa increase bone mineral density. If large clinical trials confirm its effectiveness, the manufacturer of Zometa may file for U.S. Food and Drug Administration approval in 2005.

Osteoporosis is a degenerative bone disease characterized by a reduction in bone mineral density due to a loss of calcium and collagen. Osteoporosis is a threat to 28 million Americans and is currently one of the most under-diagnosed and under-treated disorders in medicine. It is estimated that one in two women over 50 will suffer an osteoporosis-related fracture in her lifetime.

In addition to maintaining a diet rich in calcium and vitamin D, there are several drug treatments available for women who suffer from low bone mineral density. Hormone replacement therapy has been shown to be effective against osteoporosis, although it can be associated with side effects (such as bloating and vaginal bleeding) and other potential risks. Certain drugs called bisphosphonates also help strengthen bones and prevent fractures. Two commonly prescribed bisphosphonates are Fosamax and Actonel. Most women take bisphosphonates on a daily basis; however once-weekly formula of Fosamax has recently been introduced. Like HRT, bisphosphonates have side effects—most notably, gastrointestinal difficulties—and must be taken in an upright position after which patients cannot eat, drink, or lie down for at least 30 minutes.

Because only around 25% of women comply with bisphosphonate prescribing instructions, New Zealand researcher Ian R. Reid, MD and his colleagues studied the effect of administering a bisphosphonate treatment less often on women with low bone mineral density. The study, which is published in the New England Journal of Medicine, enrolled 351 post-menopausal women with low bone mineral density and treated them with either a placebo (inactive substance) or different intravenous dosages of Zometa in three, six, or 12 month intervals.

The researchers found that the women treated with Zometa experienced increases in bone mineral density (between 4.3% and 5.1% at the spine; between 3.1% and 3.5% at the femoral neck) compared to those who received the placebo. Increases in bone mineral density were similar regardless of whether the women were given infusions of Zometa at the three, six, or 12 month intervals. According to Dr. Reid and his colleagues, these increases in bone mineral density are similar to the effects of daily regimens of a bisphosphonate such as Fosamax. In the study, the most common side effects of Zometa were musculoskeletal pain, nausea, and fever.

Based on the results of the study, the researchers conclude that infusions of Zometa at intervals of up to one year produce the same effects on bone mineral density as daily treatment with other bisphosphonates. Therefore, an annual infusion of Zometa may be an effective treatment for osteoporosis and an attractive alternative to the current options.

While the study results have exciting implications, experts caution that the data must first be confirmed in larger trials before an annual Zometa infusion would be available to the public. Novartis, the manufacturer of Zometa, has already begun enrollment for two new clinical trials to further evaluate the treatment. The trials will include post-menopausal women with osteoporosis, and women and men who have experienced a hip fracture. Other smaller trials will study other uses of Zometa. According to Novartis, if these trials prove successful, the company may begin filing for FDA approval for osteoporotic fracture prevention/treatment in 2005.

Zometa is currently FDA approved to treat bone metastases (cancer that has spread from other areas, such as the breast, to the bone). At this time, Zometa is not available to U.S. women or men who suffer from osteoporosis outside of a clinical trial setting.

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