Bisphosphonates are a class of medicines used to treat various medical problems. In addition to osteoporosis, some bisphosphonates are approved for the treatment of another bone disorder called Paget’s Disease, others are used in an intravenous formulation to treat high blood calcium, and in patients with cancer in conjunction with chemotherapy.
The name is based on their chemical structure. Each medicine compound has a common chemical backbone with variations. Therefore, each medicine is unique. These medicines work by slowing down bone turnover and the breakdown of bone. As a result, the risk of fracture is decreased. In clinical trials, each medicine had varying effects on reduction of fractures. Since each medicine was tested separately with different study design and participants, comparison of one bisphosphonate to another is not possible.
FDA-approved Bisphosphonates for Osteoporosis
In the US, the four different bisphosphonate compounds are approved for treatment of osteoporosis:
Alendronate
- generic alendronate (tablet form most commonly prescribed 70 milligrams once weekly)
- Binosto® (an effervescent tablet that dissolves in water taken once weekly)
- Fosamax® (first bisphosphonate FDA-approved in 1995; although brand name may be used for prescription, usually filled with generic)
- Fosamax plus D® (brand tablet available with 2 choices for vitamin D either
Ibandronate
- generic ibandronate (tablet form 150 mg once monthly)
- Boniva® (generic version available in 2012; also available for administration by vein once every 3 months)
Risedronate
- Actonel® (tablet form most commonly prescribed 35 milligrams once weekly or in higher dosage 150 milligrams once monthly)
- Atelvia® (same medicine as Actonel but taken after breakfast once weekly)
Zoledronic acid
- Reclast® (a once yearly medicine given by vein)
FDA-labeling and Potential Risks
Bisphosphonates are under increasing scrutiny due to reports of potential side effects. The FDA changed the labeling for bisphosphonates that are indicated for treatment of osteoporosis. Now all those medicines include in their label: “The optimal duration of use has not been determined. Patients should have the need for continued therapy re-evaluated on a periodic basis.”
In addition, each prescription filled includes a “Medication Guide” that details five possible serious side effects:
1. Esophagus problems
2. Low calcium levels in your blood (hypocalcaemia)
3. Severe jaw bone problems (osteonecrosis)
4. Bone, joint, or muscle pain
5. Unusual thigh bone fractures
These serious side effects occur infrequently. However, you should be aware of them and discuss with your doctor how to properly take the medicines and your individual risks when considering one of these medicines.
Weigh Risk vs. Benefits of Bisphosphonates
In general if you are at high risk for breaking a bone due to osteoporosis or you have already had a broken bone, your risk of a fracture is high. In addition to general lifestyle measures, you can lower your risk significantly with treatment. If bisphosphonates are not right for you, other medicines are available to consider as part of your treatment regimen.