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Lower-than-standard zoledronic acid dose may decrease fracture risk
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ENDO 2011
BOSTON — One-fifth or half of the currently recommended dose of zoledronic acid may be sufficient to reduce the risk for osteoporotic fractures, Andrew Grey, MD, said here.
“If that is so, it would reduce the health care costs of treating osteoporosis … and may reduce the likelihood of side effects of the medication,” Grey, who is associate professor of medicine at the University of Auckland, New Zealand, said.
The current, manufacturer-recommended dose of zoledronic acid (Reclast, Novartis) is a 5-mg, once-yearly IV infusion. Women with osteopenia who take the drug to prevent osteoporosis receive a 5-mg dose every other year. At a press conference, Grey said annual administration has been shown to reduce the risk for fracture by 25% to 70% and to decrease mortality by 28% after hip fracture. In an earlier study, total doses of zoledronic acid lower than 5 mg, given as 3 monthly infusions, produced significant improvements in bone density. With these data in mind, the question was raised as to whether one could use lower doses on an annual basis to achieve significant skeletal benefit.
To study this, Grey and colleagues randomly assigned 180 postmenopausal women with osteopenia to a single treatment with placebo or zoledronic acid in a 1-mg, 2.5-mg or 5-mg dose. None of the women had previously received treatment with zoledronic acid or any other bisphosphonate medication. BMD tests were performed at the lumbar spine and hip before treatment during 1 year after treatment.
Results showed significant increases in BMD in each of the zoledronic acid groups at 1 year compared with the placebo group. The percentage improvement in spine BMD was similar for each zoledronic acid group: 3.5% for the 1-mg dose; 4% for the 2.5-mg dose; and 3.6% for the standard 5-mg dose (P≤.001). Change in BMD at the total hip was also significantly greater in the zoledronic acid groups vs. placebo: 2.7% for the 1-mg dose; 3.6% for the 2.5-mg dose; and 3.6% for the 5-mg dose (P≤.001).
Additionally, blood markers of bone resorption were decreased in the zoledronic acid groups compared with the placebo group.
Acute phase reaction tended to occur less frequently in the 1-mg zoledronic acid group than in either of the higher-dose treatment groups, the researchers found.
“These data demonstrate that annual administration of doses of zoledronic acid of either 1 mg or 2.5 mg produces substantial antiresorptive effects that approximate those of the 5-mg dose, and suggest that such doses may confer significant antifracture efficacy,” the researchers wrote in the study.
Disclosure: Dr. Grey reports no relevant financial disclosures.
For more information:
- Grey A. OR29-3. Presented at: The Endocrine Society 93rd Annual Meeting & Expo; June 4-7, 2011; Boston.
Historically, people have used zoledronic acid in high doses, without much consideration about the lowest dose possible to get benefit. If we can get away with giving patients less drug, then presumably you have improved the safety. Cost is not a factor. This is an injectable drug that has administration costs that are far greater than its production costs. This is purely a safety advantage, as I see it.
– Robert D. Blank, MD, PhD
Endocrine Today Editorial Board Member
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