Bisphosphonates
Bisphosphonates are a family of drugs used to prevent and treat osteoporosis. There are three bisphosphonates currently approved for use in Canada: alendronate (Fosamax ®), etidronate (Didrocal ®) and risedronate (Actonel ®).
How do they work?
Bisphosphonates bind permanently to the surfaces of the bones and slow down the osteoclasts (bone-eroding cells). This allows the osteoblasts (bone-building cells) to work more effectively.
How effective are they?
All three bisphosphonates increase bone density and prevent fractures of the spine (vertebral fractures). Alendronate and risedronate have also been shown to prevent hip fractures. Studies show alendronate and risedronate to be more effective in treating osteoporosis than etidronate.
Who can take them?
Bisphosphonates are used to prevent and treat osteoporosis in: postmenopausal women; men and women of any age who are using steroid medications; and men.
How are they taken?
Bisphosphonates have very specific instructions about how they must be taken. Following the directions will allow your body to absorb the drug properly and help you avoid side effects. Because calcium interferes with the absorption of bisphosphonates, calcium supplements must be taken at other times of the day. See table below.
Are there side effects?
The most common side effects are nausea, abdominal pain and loose bowel movements. There is a small risk of ulcers in the esophagus with both alendronate or risedronate, especially if taken incorrectly.
How to take a bisphosphonate
| |
Frequency |
Time of Day |
Instructions |
Alendronate (Fosamax®),
5 mg (prevention)
10 mg (treatment) |
every day |
first thing in morning, 1/2 hour before eating |
Taken with glass of water
Can't lie down for 1/2 hour
No calcium supplements/ vitamins for 1/2 hour |
Alendronate
(Fosamax®), 70 mg (treatment) |
once a week |
first thing in morning, 1/2 hour before eating |
Taken with glass of water
Can't lie down for 1/2 hour
No calcium supplements/ vitamins for 1/2 hour |
Etidronate (Didrocal®)
400 mg (prevention and treatment) |
every day for two weeks; then 2 1/2 months (76 days) of 500 mg calcium supplements (provided in package)* |
mid morning, mid afternoon or evening (at least two hours before or after eating) |
Taken with glass of water
No calcium supplements/ vitamins for two hours before or after |
Risedronate (Actonel®)
5 mg (prevention and treatment) |
every day |
first thing in morning, 1/2 hour before eating (preferred time) OR mid-morning, mid-afternoon, or evening (at least two hours before or after eating) |
Taken with glass of water
Can't lie down for 1/2 hour
No calcium supplements/ vitamins for two hours before or after |
Risedronate (Actonel®)
35 mg (prevention and treatment) |
once a week |
first thing in morning, 1/2 hour before eating (preferred time) OR
mid-morning, mid-afternoon, or evening (at least two hours before or after eating) |
Taken with glass of water
Can't lie down for 1/2 hour
No calcium supplements/ vitamins for two hours before or after |
*To reach your recommended daily calcium intake, you will need to eat calcium-rich foods or take a calcium supplement in addition to taking the calcium supplement included in the package.
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