Osteoporosis is defined as low bone mass with structural changes in the bone, leading to an increased risk of fractures. The body loses calcium, most commonly secondary to aging, causing the bones to weaken and potentially break. Because osteoporosis afflicts approximately 10 million people in the United States, according to the American Academy of Orthopaedic Surgeons, various treatments have been developed. One of these remedies is a zoledronic acid injection, which works to strengthen bones.
Zoledronic acid, or zolendronate, is sold under the name Reclast or Zometa. It is indicated for the treatment and prevention of osteoporosis in post-menopausal women and in men with osteoporosis. Also, because corticosteroids can weaken the bones when used long-term, zoledronic acid may be used to prevent osteoporosis in patients who need to take this type of medication for at least a year. This medication may also be used to treat Paget's disease, a condition that produces weak, fragile bones. Finally, zolendronate may be used to treat the high blood calcium levels associated with certain types of cancers of the bone.
Mechanism of Action
Zoledronic acid belongs to a group of medications called bisphosphonates. These substances help to lessen the normal breakdown of bone, which occurs as new bone is made, thereby increasing bone density. Zoledronic acid binds to bones to provide protection from fractures. A three-year trial of over 7,700 patients showed a reduction in hip and back fractures along with a documented increase in bone density in those who used zolendronate along with supplemental calcium and vitamin D.
How Zoledronic Acid Is Given
Zoledronic acid is given as a once-yearly injection. A doctor or nurse performs the intravenous injection in a medical setting. It typically requires only 15 minutes. Because zoledronic acid is given intravenously rather than orally, there are no dietary or positional restrictions such as those necessary when taking bisphosphonates by mouth. People are encouraged to drink plenty of fluids prior to the injection to ensure adequate hydration. The typical dose of zoledronate is 5mg.
The most common side effects of zoledronic acid injection are fever, body aches, headache, joint pain and flu-like symptoms. Most often, these side effects resolve within three days, but could last as long as 10 days. Taking acetaminophen may help reduce the incidence of these adverse events.
Only one type of bisphosphonate can be used at a time. The prescribing provider should be alerted to any medications being used, including over-the-counter medications and supplements. Those whose kidneys function poorly may not be candidates for zoledronic acid. It also cannot be used by patients who are pregnant or nursing or who have low blood calcium. The medical provider may request that blood work be done prior to starting therapy, including an evaluation of the kidneys and the level of blood calcium. Rarely, zoledronic acid can cause problems with the jaw bone -- a condition called osteonecrosis. Therefore, any jaw or dental problems should be promptly evaluated.
- American Family Physician: Diagnosis and Treatment of Osteoporosis
- National Institutes of Health: New Recommended Daily Amounts of Calcium and Vitamin D
- NPS RADAR: Zoledronic Acid (Aclasta) for Osteoporosis
- American Academy of Orthopaedic Surgeons: Osteoporosis/Bone Health in Adults as a National Public Health Priority