Are you one of the many taking bisphosphonates to treat your osteoporosis? Researchers recently found that taking a smaller dose, than what is normally given, appears to increase bone mineral density similar to that of the larger dose that has been given for years.
Many of us taking these medications see an increase in bone mineral density (BMD), and researchers are trying to establish whether or not a smaller dose of these drugs would provide the same BMD increases. What we don't know is whether or not this lower dose would provide less common and adverse side effects.
The drug that was tested is Zometa, a form of zoledronic acid, given in doses of 1 to 2.5 milligrams (mgs) compared to the recommended yearly dose of 5 mgs. This study was conducted at the University of Auckland in New Zealand in conjunction with the Endocrine Society.
According to Dr. Andrew Grey the bisphosphonate is indicated as a once-yearly infusion of 5 mg. but Grey said the optimal dosing regimen is still not known.
In phase II trials of the drug, several dosing regimens were equally effective in decreasing markers of bone turnover and increasing BMD, including a 2-mg dose given as 0.5 mg every three months, and a 1-mg dose given as 0.25 mg every three months.
To further investigate dosing regimens, Grey and colleagues conducted a randomized trial of 180 postmenopausal women with osteopenia who had a single, annual dose of 1 mg, 2.5 mg, or 5 mg of zoledronic acid, or placebo.
Overall, they found that change in BMD at the spine (the primary endpoint) was greater in each of the drug groups than it was among those on placebo (P<0.001).
Grey said the findings demonstrated that annual administration of lower doses of zoledronic acid produced substantial anti-resorptive effects that were similar to those of the 5-mg dose.
Further studies need to be completed before they can claim that this dosing has substantial effects on fracture prevention, but for now it seems to provide equivalent increases in bone mineral density scores, through markers of bone turnover.
As soon as fracture prevention studies are completed the authors will publish their findings for us to consider.
The data and conclusions should be considered to be preliminary until published in a peer-reviewed journal, according to Andrew Grey MD, of the University of Auckland in New Zealand.
Treatments with osteoporosis medications should be directed by fracture prevention, so until we have confirmation on this, with the lower dosing, we need to be careful with its administration since we don't have fracture studies on this yet.
- MedPageToday ENDO: Low Dose of Bone Drug Still Boosts BMD June 8, 2011Grey A, et al "A randomized controlled trial of annual low-dose zoledronate in postmenopausal women" ENDO 2011, Abstract OR29-3 http://www.medpagetoday.com/MeetingCoverage/ENDO/26925