Bisphosphonates limit the activity of certain bone cells, called osteoclasts, which help cause the bone weakening and breakdown that leads to osteoporosis.
These bisphosphonates are approved by the U.S. Food and Drug Administration (FDA) to treat osteoporosis:
- Fosamax (chemical name: alendronate sodium)
- Actonel (chemical name: risedronate)
- Boniva (chemical name: ibandronate)
- Reclast (chemical name: zoledronic acid)*
Fosamax and Actonel are available as daily or weekly doses. Boniva can be taken once a month or injected once every 3 months. Reclast is injected once a year. Together, you and your doctor can decide if one of these medicines is right for you.
There are other bisphosphonates that are being studied to protect bones during breast cancer treatment. They are:
- Zometa (chemical name: zoledronic acid) (this is a different formulation than Reclast)
- Bonefos (chemical name: clodronate)
Bonefos is not commercially available in the United States, but is available in Canada and Europe.
Both Zometa and Bonefos are usually given as injections.
Aredia (chemical name: pamidronate) is another bisphosphonate, but it is not used to treat osteoporosis. Aredia is used to reduce bone complications and bone pain caused by advanced-stage breast cancer that has spread to the bone. It's given intravenously, usually with chemotherapy medicines.
*In 2011, the FDA warned doctors and patients that Reclast may cause severe kidney problems. Kidney problems after getting Reclast are more likely in women who:
- already have kidney problems
- take a diuretic (medicine that removes water from the body)
- are dehydrated when they get a Reclast injection or become dehydrated afterward
- take other medicines that can cause kidney problems
- are older
It’s now recommended that women scheduled to get Reclast drink at least two glasses of water or other liquid within a few hours of treatment to reduce the risk of kidney problems.
Other research suggests that Reclast may increase levels of sclerostin, a protein made by osteocytes, a type of bone cell. Higher levels of sclerostin may lead to lower levels of bone formation. It’s not clear yet if higher levels of sclerostin are causing problems for women being treated for osteoporosis. If you’re prescribed Reclast, you may want to talk to your doctor about this research and ask if it’s relevant to your unique situation.
Bisphosphonates may cause rare but serious side effects
Research has shown that bisphosphonates can increase the risk of atypical femur fractions when taken for 5 years or longer. The femur is the large leg bone that runs from your hip to your knee. An atypical fracture means that the bone is broken in an unusual spot. Still, atypical femur fractures are rare -- only about 0.22% of women taking a bisphosphonate for more than 5 years will have an atypical femur fracture.
The bisphosphonates also can sometimes cause another rare but serious side effect, osteonecrosis of the jaw, a condition in which the cells in the jawbone start to die. Researchers think that osteonecrosis of the jaw may develop because bisphosphonates stop the body from repairing microscopic damage to the jawbone that can happen during routine dental procedures or from everyday wear and tear. But it's still not clear why this happens in some people and not in others. If you're taking a bisphosphonate, tell your dentist right away. Together, you and your dentist can work out a dental treatment schedule that keeps your teeth healthy and minimizes your risk of osteonecrosis of the jaw.
Bisphosphonates must be taken in a specific way to avoid serious complications:
- You take bisphosphonates with a full glass of plain (not seltzer) water only, on an empty stomach.
- You must wait 30 minutes after taking a bisphosphonate before you eat or take other medicine.
- You can’t lie down for at least 30 minutes after taking a bisphosphonate. This is to avoid irritating your esophagus (the tube from your mouth to your stomach), as well as other gastrointestinal side effects and heartburn. These side effects aren’t common, but if you already have them or develop them after starting bisphosphonate treatment, ask your doctor if you can get a bisphosphonate injection or another type of medicine.