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Osteoporosis Canada educates, empowers and supports individuals and communities in the risk-reduction and treatment of osteoporosis.

 
 

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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