Bone-building medicine, how long do you have to take it

Q: My doctor wants me to start taking a particular medication once a week to strengthen my bones. How long do I have to take it?

May is National Osteoporosis Awareness and Prevention Month. Osteoporosis is a disease that causes your bones to become thinner and more likely to break. If you have osteoporosis, a simple fall can shatter a bone, causing months of painful rehabilitation and, for some, permanent disability and loss of independence.

Sometimes, bones become so weak that they break spontaneously. A hip fracture can cause a fall instead of being the result of one. The vertebrae of your spine can become so frail that they collapse. Your nerves can get pinched, and your muscles can twist out of position, causing deformity and pain.

Last summer, I drove past a line of heavy equipment which was resurfacing a lane of traffic on the opposite side of the highway. The leading machine ripped into the top asphalt layer, shredding it and moving it up a conveyer belt into a waiting dump truck. Behind them, a second dump truck fed crushed asphalt into one end of a mixer, blending it with hot tar. The mixer’s other end poured hot gooey asphalt onto the road surface. A giant roller followed behind for the final touch.

Our bones follow a similar pattern, continuously recycling the calcium, phosphorus, and other minerals that they contain. Like the machines that chew up the top layer of roadway, remix it and lay it down as a new surface, we continuously take up bone cells, then lay them back down.

Until age 35, our bone density increases every year as we are putting in more bone cells than we take out. That balance begins to shift in your mid-thirties. You begin losing about 1% of your bone mass every year.

Taking prednisone for months to years at a time decreases bone density, and smoking cigarettes accelerates bone loss. Menopause triggers a doubling of the rate of bone loss in most women. 

How long do you need to take your bone-building medicine? It depends on how thin your bones are and whether you have a history of a fracture due to having thin bones. Bone density is measured using a DXA scan (also called a DEXA). DXA scans measure bone thickness in several critical areas to determine bone mineral density.

During a painless PET scan, two low-dose X-rays penetrate the bones of your pelvis, hip, and lower spine. The results are used to calculate the bone mineral density of each area, with the lower the density, the greater the risk of fracture.

If your bone density is low, you can reduce future bone loss with treatment. You may be at an increased risk of thin bones if you are post-menopausal or have taken certain drugs frequently, particularly prednisone.

About half of repeat fractures related to osteoporosis can be prevented with appropriate treatment.

Bone-building drugs like alendronate (Fosamax®), risedronate (Actonel®), and Boniva® are called bisphosphonates. These powerful medicines have very complicated directions. Most women prefer to take them once a week instead of every day. In addition, these medicines need to be taken with a full glass of water on a completely empty stomach and sitting upright for at least 30 minutes after taking it.  

Keeping yourself upright and drinking a full glass of water helps avoid irritating your esophagus. Having an empty stomach is essential because only 2-3% of the medicine in each tablet will get absorbed into your body.

What does get into your bones stays there. These drugs become part of your bone cells and help build bone for you even years after stopping these medications.

Another form of bisphosphonate is a yearly infusion. This is particularly helpful if you cannot take the pill form because of stomach or esophagus problems.

So how long should you take Fosamax® or Actonel®?

The answer to that is, "That depends". I suggest you and your doctor make a choice together. Five years of treatment with any bisphosphonate should be long enough if you take it as prevention and have never had a fracture.

Both alendronate (Fosamax®) and risedronate (Actonel®) help prevent hip and vertebral fractures for up to ten years, even after you stop taking them.

When you take a bisphosphonate for longer than five years, there is an increased risk of a dental emergency called osteonecrosis of the jaw.

Besides bisphosphonates, there are other bone-building medications available, including once-monthly injections. Check with your doctor about all of your medication options. 

Dr. Louise Achey, Doctor of Pharmacy, is a 43-year veteran of pharmacology and the author of Why Dogs Can't Eat Chocolate: How Medicines Work and How YOU Can Take Them Safely. Get clear answers to your medication questions at her website and blog

©2022 Louise Achey


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