Bones are constantly being remodelled (the process by which old bone tissue is replaced by new bone tissue). Different types of cells work to remodel bones. Osteoblasts build new bone. Osteoclasts break down and remove old bone. Bisphosphonates are drugs that stop the body from breaking down bone. They also help strengthen bones. Bisphosphonates are used to help protect bones against the effects of some cancers and to treat other bone-related conditions.
Uses for bisphosphonates
Cancer and other diseases can speed up the breakdown of bone. When bones break down, calcium is released into the blood. Bisphosphonates bind to the surface of bones and slow down bone breakdown. This helps reduce calcium loss from the bones.
Because bisphosphonates slow down the breakdown of bones, they may be used to:
- relieve bone pain caused by multiple myeloma or bone metastases
- reduce high levels of calcium in the blood (hypercalcemia)
- help strengthen bone and reduce the risk of fractures caused by cancer, bone metastases or osteoporosis
Bisphosphonates are usually used along with other cancer treatments.
Cancer and bone pain
Some advanced cancers, such as breast or prostate cancer, can spread to the bone (bone metastasis). Other cancers, such as multiple myeloma, stimulate osteoclasts (the bone-eroding cells) so that bone breaks down faster than normal.
Both bone metastases and multiple myeloma can cause bone pain. Bisphosphonates help slow down bone breakdown to relieve bone pain. Bisphosphonates are often given with other treatments to relieve bone pain, such as nonsteroidal anti-inflammatory drugs (NSAIDs).
When cancer spreads to the bone or causes bones to dissolve, calcium moves out of the bones and into the bloodstream. This can cause calcium levels in the blood to rise. A high level of calcium in the blood is called hypercalcemia. This can also cause bones to become weak and fragile so that they break (fracture) easily.
Bisphosphonates help treat hypercalcemia by slowing down bone breakdown.
A loss of bone mass (or bone density) is called osteoporosis. This condition causes bone to become weak and more likely to break. There are many risk factors for osteoporosis, including some cancer treatments, such as long-term corticosteroidcorticosteroidAny steroid hormone that acts as an anti-inflammatory by reducing swelling and lowering the body’s immune response (the immune system’s reaction to the presence of foreign substances). use, hormonal therapieshormonal therapiesTreatment that adds, blocks or removes hormones. and some chemotherapy drugs. Osteoporosis can also occur as a result of aging and other factors not related to cancer.
Bisphosphonates may be used to prevent and treat osteoporosis.
Types of bisphosphonates
Different types of bisphosphonates are used to treat bone metastases. The type of bisphosphonate used can depend on the type of cancer being treated. They may include:
- clodronate (Bonefos)
- pamidronate (Aredia)
- zoledronic acid (Zometa)
Other bisphosphonates are used to prevent and treat osteoporosis:
- alendronate (Fosamax)
- risedronate (Actonel)
- etidronate (Didrocal, Didronel)
Researchers are studying a new bisphosphonate called ibandronate (Boniva). It will be used to treat osteoporosis. This drug is not yet available in Canada.
Bisphosphonates can be given in 2 ways. They can be taken as pills (orally) or given by a needle into the vein (intravenously).
- Pills are usually taken once or twice per day. They should be taken on an empty stomach. People should wait at least 30 minutes before eating or drinking anything or taking another medicine, including vitamin and mineral supplements.
- Intravenous treatments are usually given every 3–4 weeks. The treatments can take anywhere from 15 minutes to 4 hours, depending on which bisphosphonate is given. They can be given at the hospital or at home by a homecare nurse.
When bisphosphonates are given to relieve bone pain caused by bone metastases:
- The doctor will assess if the person’s pain has lessened and if it is being controlled.
- Bisphosphonates can affect the kidneys, so the doctor will check kidney function.
When bisphosphonates are used to treat hypercalcemia:
- Blood calcium levels are checked to see if they are going down and the person is responding to treatment.
- The doctor will check kidney function.
When bisphosphonates are used to prevent and treat osteoporosis:
- A bone mineral density test is done to check the response to bisphosphonates.
- The doctor will assess if bone tenderness or pain has lessened.
- Kidney function may be checked.
For more detailed information on specific drugs, go to sources of drug information.