Alendronate – for bone supremacy

Hello my friend,

Here’s a universal truth – every one of us is growing older – constantly. Every minute. Without exception. And although the effects of age show up slower in some of us than others, they do eventually appear, albeit as unwelcome guests. We’ve got to fight for our youth and health. We can’t just let entropy take over.

One of these unwelcome guests is bone fragility. Why is there a greater risk of fracture as we grow older? Here’s why. Our bone tissue is a dynamic environment. There is constant bone-building and bone breakdown. Bone formation results from the activity of cells called osteoblasts – bone-builders, and bone resorption (breakdown and re-assimilation) due to the activity of bone cells called osteoclasts – bone-breakers. Estrogen is a “female” hormone that is formed in the body of both men and women, appropriate to the age and sex of the individual. Obviously, there is more estrogen in the body of a pre-menopausal woman than a man of the same age.

In less amounts than required to create female sex-specific effects, estrogen inhibits osteoclasts, the bone-breakers, thus minimizing bone resorption. It also activates the bone-building processes. In women, estrogen is primarily made by the ovaries. In men, estrogen is mainly formed by conversion of the male hormone testosterone.

At menopause, the ovaries cease to make estrogen. The drop in estrogen levels results in increased bone resorption and decreased bone formation. This leads to reduction in bone mineral density (BMD) and increased risk of fracture. This condition is called osteoporosis. Although most common in post-menopausal women, it can occur in men too, as well as in men or women with hormonal disturbances, or due to some kinds of medicine (specific steroids called glucocorticoids).

Osteoporosis is prevented/treated with lifestyle changes like exercise, nutrition including calcium and vitamin D and medicine. Bisphosphonates are a class of medicine that have been used effectively in preventing and treating osteoporosis. Nitrogen-containing bisphosphonates are more effective than non-nitrogenous bisphosphonates. Alendronate, sold in the generic form as well as brand Fosamax is a widely used nitrogenous bisphosphonate.

When taken orally, less than one-hundredth of the dose is absorbed under fasting conditions, even less when taken with food. Half of the absorbed medicine is excreted unchanged by the kidneys, the other half is rapidly bound to exposed bone surface in the body. Once it’s absorbed by the bone, its half-life is about 10 years. What that means is that half of the alendronate is rid off by the body in 10 years, then half of the remaining half is eliminated by the body in another 10 years and so on.

Alendronate binds to the osteoclasts (the cells responsible for bone resorption, the bone-breakers), specifically inhibits an enzyme, thus blocking a protein transfer pathway within the osteoclasts. This messes with the functioning of the osteoclasts. As a result, the osteoclasts cease to do their job of bone resorption.

Bone-building continues in the presence of calcium, vitamin D and other factors. This results in increased bone density.

Are there side-effects? All drugs have side-effects. Alendronate can cause ulcers – esophageal (gullet), gastric (stomach) and duodenal (the first section of the small intestine). To reduce the incidence of ulcers, it is required that one sit or stand straight or walk for 30 minutes after ingesting the drug. Taking this medicine with a full glass of water on an empty stomach improves absorption. If dental work is done while on this medication, there is a risk of osteonecrosis (literally means bone death) of the jaw – this is rare on oral administration, more likely when alendronate is administered intravenously, mostly seen in cancer patients.

If alendronate is administered with food or a beverage other than water, absorption is reduced – this is more so with calcium, magnesium or aluminum-containing food or drugs – that includes dairy and antacids. Hormone replacement therapy along with alendronate may help with post-menopausal women.

Alendronate is usually administered in a daily dose of 10 mg or a weekly dose of 70 mg for treatment of osteoporosis. It can be administered in a daily dose as low as 5 mg or a weekly dose of 35 mg for prevention of the same. For Paget’s disease of the bone (enlarged or deformed bones – hereditary or due to a long-standing slow viral infection like measles), it’s a daily dose of 40 mg for six months.

We live in good times. Science, nutrition, lifestyle, medicine and technology give us longer and better quality lives. Are the solutions perfect? Certainly not. Does medicine lead to adverse effects. Of course. However, we can discuss options with our professionals and take the best course of action. Awesome!

My friend, until next time, do take care of yourself and your health.

Dr. Ajit Damodaran


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