Osteopenia is a term used to describe bone density that is somewhat lower than normal -- but not low enough to be diagnosed as osteoporosis. Osteoporosis is a condition in which thinning bones become so fragile that they are prone to fracture easily. A person who has osteopenia is at risk for osteoporosis and may benefit from treatments to strengthen bone.
Bisphosphonates affect what's called the bone remodeling cycle, which involves bone resorption (the dissolving of existing bone tissue) and formation (the filling of the resulting small cavities with new bone tissue). Usually, these two parts of the cycle are balanced, but when resorption outpaces formation, you eventually have osteoporosis.
By slowing or stopping the bone-resorbing portion of the remodeling cycle, bisphosphonates allow new bone formation to catch up with bone resorption. Fosamax and other drugs such as Actonel, Boniva, and Reclast increase bone density and help prevent and treat osteoporosis and/or reduce the risk of fractures.
Increasing Bone Density
"Over three years on Fosamax, you can expect a 6% to 8% increase in spinal bone density and a 4% to 6% increase in hip bone density," says Michael Holick, MD, PhD, a professor of medicine, physiology, and biophysics at Boston University Medical Center. "And the bisphosphonates have been found to reduce spinal fracture by as much as 60% over three years, and hip fractures by as much as 50%."
Recently completed studies show that these effects continue with long-term use. "You see the most dramatic effect in the first three to five years on the medications, but we continue to see a smaller but significant increase in bone density for up to 10 years," Holick says. "More important, if you stop taking the drugs, you begin to lose bone at the same rate you would have before."
But bisphosphonates do have some limitations. For one thing, the regimen for taking them effectively is very intense. Since as little as 1%- 5 % of the drug is absorbed by your body -- the rest is excreted -- you have to make sure to make the most of every dose. With drugs like Fosamax and Actonel, this means taking it first thing in the morning once a week -- and then not ingesting anything else for half an hour to an hour.