Bisphosphonates are a family of drugs used to treat osteoporosis. There are four bisphosphonates currently approved for use in Canada: alendronate (Fosamax ®), etidronate (Didrocal ®), risedronate (Actonel ®) and zoledronic acid (Aclasta®). Also available are: Actonel® Plus Calcium, and Fosavance® (Fosamax® with vitamin D).
Bisphosphonates bind to the surfaces of the bones and slow down the bone resorbing action of the osteoclasts. This allows the osteoblasts to work more effectively.
All four bisphosphonates increase bone density and prevent vertebral fractures. Alendronate, risedronate and zoledronic acid have also been shown to prevent hip and non-vertebral fractures.
Bisphosphonates are used to treat osteoporosis in: postmenopausal women and in men; and in men and women of any age who are using steroid medications.
Bisphosphonates have very specific instructions about how they must be taken in order to be absorbed properly and avoid side effects. Because calcium interferes with the absorption of bisphosphonates, calcium supplements must be taken at other times of the day. See details on the Osteoporosis Canada website.
The most common side effects are nausea, abdominal pain and loose bowel movements. Bone, joint and/or muscle pain has been infrequently reported in patients taking bisphosphonates. There is a small risk of ulcers in the esophagus with both alendronate and risedronate, especially if taken incorrectly.
The most common side effects of zoledronic acid, which usually only last a day or two, are fever, pain in the muscles, bones or joints and headache. There have been rare cases of acute renal dysfunction following infusion of zoledronic acid.
In very rare cases, alendronate, risedronate and zoledronic acid have been linked to a breakdown of the jaw bone (called osteonecrosis of the jaw) following dental work such as dental extractions. Rare cases of atypical fractures of the femoral (thigh) bone have been reported with bisphosphonates. One should notify their physician if they experience pain in the groin or thigh that is present for a few weeks.
Denosumab (Prolia®) belongs to a new class of osteoporosis treatment called a Rank ligand inhibitor.
Denosumab is an anti-resorptive treatment that inhibits the development and activation of osteoclasts (the cells that eat away bone).
Denosumab reduces the risk of fractures of the spine, hip and other sites in women with postmenopausal osteoporosis.
Denosumab can be used to reduce the risk of fractures in postmenopausal women with osteoporosis. As of October 2010, the clinical trials using denosumab in men with osteoporosis are ongoing.
Denosumab is an injection under the skin given by a trained healthcare professional, twice a year. The dose is 60 mg.
Side effects may include pain in the muscles, arms, legs or back and a skin condition with itching, redness and/or dryness. It also slightly increases the risk of cellulitis, a skin infection that is treated with antibiotics. In rare cases, osteonecrosis of the jaw has been reported in patients treated with Denosumab.