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Six-year zoledronic acid regimen safe, effective.


TORONTO--Patients who continued annual treatment with zoledronic acid for 6 years had significantly better bone mineral density and fewer morphometric vertebral fractures than did patients who received 3 years of treatment and then stopped, in a controlled study with more than 1,200 patients.

Six years of annual zoledronic acid treatment also proved safe, Dennis M. Black, Ph.D., said at the meeting.

"After 3 years, it might be beneficial for some women, particularly those at high vertebra! fracture risk, to continue zoledronic acid for an additional 3 years," said Dr. Black, professor of epidemiology and biostatistics at the University of California, San Francisco.

"These new findings show that continued treatment with zoledronic acid for 6 years continues to maintain bone mass and reduced vertebral fracture risk with no change to its favorable safety profile," he said in a written statement.

With the new finding, zoledronic acid joins other bisphosphonates, such as alendronate, shown to prevent loss of bone density when the drug is continued after several years of treatment. In a prior report, continuing treatment with alendronate for 5 years after an initial 5 years of treatment led to less bone density loss than in patients who switched from al-endronate to placebo (JAMA 2006;296: 2927-38).

The new zoledronic acid findings came from an extension of the Health Outcomes and Reduced Incidence With Zoledronic Acid Once Yearly (HORIZON) Pivotal Fracture Trial, which compared a single, annual infusion of zoledronic add with placebo in postmenopausal women with osteoporosis during 3 years of treatment (N. Engl. J. Med. 2007;356:1809-22).

Dr. Black and his associates randomized 1,233 women who completed the zoledronic acid arm of the study to either another 3 years of annual infusions of 5 mg zoledronic acid or placebo. Their mean age was 76, and about 55% had a femoral neck T score of less than -2.5.

At the end of the study, the percent change in femoral neck bone mineral density, compared with the level at entry into the study, averaged 1% higher in the zoledronic acid patients, a significant difference. Femoral neck bone density in the zoledronic acid-treated patients grew by an average of 1.4% over their baseline 6 years earlier, compared with those who switched off the bisphosphonate after 3 years, also a significant difference.

The rate of morphometric vertebral fractures during the 3 years of the new study totaled 6% with placebo and 3% with zoledronic acid, a significant difference. There was no significant difference in rates of nonvertebral fractures.

There was no excess of adverse events in the zoledronic acid group compared with patients on 3 years of placebo.


Major Finding: Postmenopausal women with osteoporosis who received an annual injection of zoledronic acid for 6 years maintained their femoral neck bone mineral density significantly better than patients treated with the drug for 3 years followed by 3 years on placebo.

Data Source: Extension of the HORIZON Pivotal Fracture Trial, a randomized, multicenter extension trial with 1,233 women.

Disclosures: The HORIZON Pivotal Fracture Trial was funded by Novartis, which markets zoledronic acid (Aclasta). Dr. Black said that he has served as a consultant and done teaching for Amgen and Nycomed, and that he has received research contracts from Amgen, Merck, Novartis, and Roche/Genentech.
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Title Annotation:ENDOCRINOLOGY
Author:Zoler, Mitchel L.
Publication:Internal Medicine News
Article Type:Report
Geographic Code:1CANA
Date:Nov 15, 2010
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