Bisphosphonates
Bisphosphonates are a family of drugs used to prevent and treat osteoporosis. There are four
bisphosphonates currently approved for use in Canada: alendronate (Fosamax ®), etidronate (Didrocal ®) and
risedronate (Actonel ®). Also available are: Actonel® Plus Calcium, Fosavance® (Fosamax® with vitamin D) and
zolendric acid (Aclasta®).
How do they work?
Bisphosphonates bind to the surfaces of the bones and slow down the bone resorping action of the
osteoclasts (bone-eroding cells). This allows the osteoblasts (bone-building cells) to work more
effectively.
How effective are they?
All four bisphosphonates increase bone density and prevent fractures of the spine (vertebral fractures).
Alendronate, risedronate and zolendric acid have also been shown to prevent hip fractures. Etidronate is the
least effective of the bisphosphonate drugs.
Who can take them?
Bisphosphonates are used to prevent and treat osteoporosis in: postmenopausal women and in men; and in men
and women of any age who are using steroid medications.
How are they taken?
There are very specific instructions about how bisphosphonates must be 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 may 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. Bone, joint and/or
muscle pain has been reported in patients taking bisphosphonates; such reports have been infrequent. 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, flu-like symptoms and headache. 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 or injury to the oral cavity (read more about this here).
How to take a bisphosphonate
| |
Frequency |
Time of day |
Instructions |
Alendronate (Fosamax®),
5 mg (prevention)
10 mg (treatment) |
every day |
first thing in morning, at least 1/2 hour before
eating |
Taken with glass of water
Can't lie down for 1/2 hour
No calcium supplements/ vitamins for at least 1/2 hour |
Alendronate
(Fosamax®),
70 mg (treatment)
(Fosavance®)
70 mg + 2800 IU vitamin D
70 mg + 5600 IU vitamin D
(treatment)
|
once a week |
first thing in morning, at least 1/2 hour before
eating |
Taken with glass of water
Can't lie down for 1/2 hour
No calcium supplements/ vitamins for at least 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, at least 1/2 hour before
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, at least 1/2 hour before
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® Plus Calcium) 35 mg
+ 500 mg elemental calcium
(prevention and treatment) |
once a week
calcium carbonate 6 days/week |
first thing in morning, at least 1/2 hour before
eating |
Taken with glass of water
Can't lie down for 1/2 hour
No calcium supplements/ vitamins for two hours before or after
Take calcium carbonate tablets with food
|
Risedronate (Actonel®)
75 mg (treatment) |
two consecutive days, once a month |
first thing in morning, at least 1/2 hour before
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®)
150 mg (treatment) |
once a month |
first thing in morning, at least 1/2 hour before
eating |
Taken with glass of water
Can't lie down for 1/2 hour
No calcium supplements/ vitamins for two hours before or after |
Zolendric acid (Aclasta®)
5 mg (treatment)
|
once a year |
not applicable |
Given as a 15-minute intravenous (IV) infusion by a certified
healthcare professional |
*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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