The following is an excerpt from the Mayo Clinic Press book Mayo Clinic on Osteoporosis by Ann E. Kearns, M.D., Ph.D.
Getting enough calcium and vitamin D in your diet and being physically active are key components of any plan for preventing and treating osteoporosis. But these measures alone can’t completely offset bone loss due to aging and, in women, the onset of menopause. Diet and exercise also aren’t sufficient to treat osteoporosis once your bones are already weakened. Medications are often prescribed to help slow or reverse bone loss and reduce your risk of fractures.
Your doctor may prescribe medication to prevent or treat osteoporosis if:
• You’ve been diagnosed with osteoporosis based on a fragility fracture or bone density measurement
• You have low bone density, are postmenopausal or otherwise have an increased risk of fractures
• You have a condition or are using medications that increase your risk of fracture or rapid bone loss
• You experience continued bone loss or a fracture, even though you’re physically active and get adequate dietary intake of calcium and vitamin D or are taking supplements
The medication your doctor recommends will be based on a variety of factors. All medications discussed in this chapter are approved for use in postmenopausal women, while some are approved for use in men and some for use in specific situations. The choice of medication is often based upon effectiveness, safety, cost, convenience and other factors.
There are two main categories of osteoporosis medications, based on how the drugs work. Anti-resorptive medications slow the breakdown of bone in the remodeling process. These are also knownas bone-stabilizing drugs. Anabolic medications are bone-building therapies, helping to promote bone formation. Both classes of medications can change the net effect of the bone remodeling cycle, slowing or even reversing the loss of bone.
Anti-resorptive medications
Anti-resorptive drugs include bisphosphonates — the most common type of osteoporosis medication — and several others. These therapies work in various ways to prevent bone breakdown, preserve bone mass and reduce the risk of fracture. When you take these medications, the rate at which you lose bone mass slows. Your bone density typically increases as a result.
Bisphosphonates
For both women and men, the most widely prescribed osteoporosis medications are bisphosphonates. Bisphosphonates are often preferred because of their effectiveness and relatively low cost and the availability of long-term safety data.
Bisphosphonates alter the actions of osteoclasts, the bone-excavating cells, and halt their functions. (Turn to Chapter 2 for more on osteoclasts’ role in bone remodeling.) By doing so, bisphosphonates slow bone loss and increase the mineral content of bones.
This can effectively preserve bone mass and even increase bone density in your spine and hip, thereby reducing your risk of fractures.
Oral vs. IV
Bisphosphonates may be taken by mouth (orally) — in pill form or dissolved in water, depending on the drug — or they may be given through an IV. Oral bisphosphonates include the medications:
• Alendronate (Binosto, Fosamax)
• Risedronate (Actonel, Atelvia)
• Ibandronate (Boniva)
These oral medications may be taken daily, weekly or monthly, and they generally increase bone density of the lumbar spine by approximately 5% to 10%. They also reduce the risk of new spinal fractures by 40% to 70%, and some can reduce the risk of hip fractures by about 30% to 40%.
Oral alendronate and risedronate are often the first line of treatment for postmenopausal women and men with osteoporosis. These medications are also approved for the prevention and treatment of osteoporosis due to glucocorticoid use. Ibandronate is approved for use only in postmenopausal women, however.
The most common side effects of oral bisphosphonates are heartburn and abdominal pain caused by irritation to the esophagus or stomach. Taking the medications once a week or once a month doesn’t appear to cause fewer stomach problems than does taking them daily.
Two bisphosphonates are available as IV medications — drugs that are given directly into a vein.
• Zoledronic acid (Reclast) is administered as an infusion once a year.
• Ibandronate is given by injection once every three months.
The injected form of ibandronate, like the oral route, is approved for postmenopausal women. Zoledronic acid is approved for use in postmenopausal women, men and those with glucocorticoid-induced osteoporosis.
These medications are typically administered in a hospital or at an outpatient infusion therapy center. Because they don’t cause gastrointestinal upset, intravenous medications offer an excellent alternative for postmenopausal women who may not be able to take oral bisphosphonates. Zoledronic acid may also have advantages over oral bisphosphonates in some people. This includes individuals with certain types of breast cancer who are taking aromatase inhibitor therapy and people who’ve had a heart transplant in the past year.
Which is better?
Both forms — oral and IV — are effective. The type you receive generally depends on your preferences and your insurance. There are some advantages to IV bisphosphonates. Researchers have found that many women taking an oral bisphosphonate stop treatment or take less than prescribed after one year of use. This reduces the effectiveness. A yearly or quarterly IV dose ensures that you’re fully protected until the next treatment.
Some people take several pills daily to manage other health problems and don’t want to take yet another pill. And some individuals experience stomach upset from oral bisphosphonates. These people may prefer an IV medication.
Safety
Bisphosphonates have been studied for decades, and have a low risk of serious side effects. The drugs may not be recommended if you have severe uncontrolled heartburn or gastroesophageal reflux disease (GERD) or severely reduced kidney function. Your doctor will likely evaluate the safety and effectiveness of your medications on a yearly basis.
Bisphosphonates are also used to treat other bone diseases, such as Paget’s disease of bone, and bone affected by cancer that has spread from other organs. Typically, these treatments are given intravenously and more frequently.
In case of a fracture
Osteoporosis medications lower the chance of fracture, but they don’t eliminate all risk of breaking a bone. If you have a fracture while taking bisphosphonates, your doctor will reassess you. He or she may look into whether other health problems might have contributed to the broken bone.
Depending on the outcome of that assessment, you may be a candidate to switch to a more potent bone-building therapy. This might include parathyroid hormone (PTH), manufactured as teriparatide (Bonsity, Forteo) and abaloparatide (Tymlos), or sclerostin antibody therapy in the drug romosozumab (Evenity). Romosozumab both reduces bone resorption and increases bone formation by inhibiting sclerostin, a major regulator of bone activity that’s produced by osteocytes.
These treatments are typically reserved for women who are at very high risk of a fracture — those with very low bone density or who have had fractures. Teriparatide may also be used in certain men. All of these therapies have the potential to rebuild bone and actually reverse osteoporosis, at least somewhat.
Relevant reading
Mayo Clinic on Osteoporosis
Around 54 million Americans live with osteoporosis or low bone mass, but many don’t recognize the symptoms until it is too late. Before a bad fall or fracture renders you immobile, learn how to reduce your risk of developing osteoporosis, manage your day-to-day symptoms, and even treat the disease with the tools provided in Mayo Clinic on Osteoporosis.
