What are bisphosphonates?

David Slovik, MD
Endocrinology Diabetes & Metabolism
For years, a group of medications known as bisphosphonates have been the first choice of doctors and patients alike for treating or preventing osteoporosis. What's changed of late is how often you need to reach for these medications. Once they were available only in daily doses; now, few patients take the tablets that often. Instead, more and more people are opting for weekly or monthly formulations. Medications that are taken just once a week or once a month appeal to consumers because of their convenience. One of the medications in this class, zoledronic acid (Reclast), is taken just once a year, as an infusion. Another medication in this group, ibandronate can be given intravenously every three months.
Bisphosphonates have become the mainstays of treatment because they reduce hip, wrist, and spinal fractures and because they have few side effects when they are taken properly. These attributes have made bisphosphonates an attractive alternative to hormone therapy, which was once widely used for stemming bone loss but has fallen out of favor.
The oral bisphosphonates typically prescribed for osteoporosis are alendronate (Fosamax), risedronate (Actonel), and ibandronate (Boniva). Like most of the medications approved for treating osteoporosis, bisphosphonates are antiresorptive, meaning that they reduce bone resorption or turnover. They slow bone loss and produce modest increases in bone density. Specifically, the bisphosphonates bind themselves to hydroxyapatite (the cement-like substance in bones) and interfere with bone-depleting osteoclasts, narrowing the gap between osteoclast activity and osteoblast activity. As a result, osteoblasts (which build bone) have an opportunity to fill in more of the trenches left by osteoclasts.
Scott D. Martin, MD
Orthopedic Surgery
Bisphosphonates are a class of antiresorptive agents which increase bone density by slowing the rate of bone loss. Drugs in this class include risedronate (Actonel) and alendronate (Fosamax), both available in daily and weekly doses, and ibandronate (Boniva), which comes in daily or monthly doses. These drugs reduce the risk of spine, wrist, and hip fractures by 40% to 50%. But they may increase the risk of some kinds of fractures, such as intertrochanteric fracture. The Food and Drug Administration (FDA) is reviewing this safety concern. Most people can take these drugs without side effects, but they can sometimes irritate the esophagus and stomach, causing heartburn and nausea. Another drawback is that once a person starts taking them, he or she needs to continue taking them for life or risk a sharp drop in bone density.
Bisphosphonates help slow down or stop bone loss and are used to treat osteoporosis. In addition, they are used in peoples with bone tumor. After a bone tumor is destroyed, bisphosphonate drug therapy may be given to peoples, orally or intravenously. This therapy helps strengthened bones weakened by tumors. Bisphosphonate drug therapy may be used with PMMA bone cement, a medical grade cement that doctors use to surgically fill a void within a bone after a tumor is destroyed. PMMA helps strengthen the bone and prevent the tumor from recurring.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.