Michele Bellantoni, M.D., Associate Professor of Medicine and Medical Director, Johns Hopkins Bayview Care Center, answers questions on Reclast (zoledronic acid) – the new once-a-year-osteoporosis drug.
What is zoledronic acid?
Zoledronic acid belongs to a class of drugs called bisphosphonates. A form of zoledronic acid called Zometa has been used for many years to treat certain cancers, and Reclast is approved to treat Paget’s disease, which causes enlarged or misshapen bones. Oral bisphosphonates, such as Fosamax (alendronate) and Actonel (risedronate), have been used to treat osteoporosis for over 10 years.
Data on how well this new treatment works for osteoporosis were published in The New England Journal of Medicine (NEJM). What did the NEJM study find?
Researchers assigned 3,889 osteoporosis patients to receive an I.V. infusion of either zoledronic acid or a placebo. The infusions were repeated once a year for three years. Women who received zoledronic acid had a 70% decrease in the risk of vertebral fractures and a 41% decrease in hip and other fractures. But the women also had an increased incidence of atrial fibrillation.
Do you have concerns about the safety of Reclast?
Yes. Although reports of irregular heartbeats, or atrial fibrillation, were uncommon in the NEJM study, when a serious adverse effect like this is seen in a clinical trial, the concern is that the complication will be seen in even more patients after the drug is approved and used more widely.
How does Reclast compare with the oral forms of osteoporosis treatment?
The oral bisphosphonates have been used for a long time for osteoporosis, and we know a lot more about their safety profiles and efficacy. When a new drug becomes available, you always have to ask what this new treatment offers over the old treatments. Clearly the once-a-year administration of Reclast for osteoporosis is an advantage, but there is the potential for side effects like atrial fibrillation that we don’t see with oral osteoporosis therapy. I wouldn’t try Reclast instead of other osteoporosis medications. Until more safety data are available, I will reserve Reclast for osteoporosis patients who cannot tolerate oral therapy.
Who will benefit from Reclast?
What Reclast offers is an alternate way of getting bisphosphonates to the small minority of people who have unique gastrointestinal conditions that prevent them from taking the oral osteoporosis medications. If wider use shows that the atrial fibrillation is not a significant issue, then more patients may be able to try Reclast for its convenience over other options, and this is important.
What else should people know when considering osteoporosis treatment?
I think it’s important to mention the profound importance of calcium and vitamin D. None of these bisphosphonates will work -- in fact, they could even harm bone -- if the osteoporosis patient does not take adequate calcium and vitamin D. These medications keep protein in the bone. But the bone is not strong until calcium is deposited on the protein. And vitamin D helps our body absorb the calcium. So we need both these building blocks.
I recommend 400 International Units (IU) of vitamin D per day for men and women age 51–70 and 800 IU for those over 70. And you need between 1,200 and 1,500 mg of calcium daily as well, either through food or supplements.
