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Clinical Updates
Intravenous bisphosphonate offers once-a-year alternative to pill regimen for osteoporosis
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Oral bisphosphonates have been shown effective in slowing bone loss and increasing bone density in postmenopausal women. But many patients fail to comply with their dosing regimen, resulting in preventable fractures.
An FDA-approved intravenous bisphosphonate (zoledronic acid) offers a once-a-year alternative to pills. The treatment is administered by a healthcare provider in a 5 mg dose via infusion lasting about 15 minutes. The dose is effective for 12 months, during which time women need not take bisphosphonate in any other form.
Osteoporosis affects about 10 million people in the United States, 80 percent of them women. The disease, which occurs most frequently in post-menopausal women, is usually asymptomatic. The only way to diagnosis osteoporosis with certainty is a bone mineral density test, the most common of which is a DEXA bone scan.
Bisphosphonates are anti-resorption drugs that slow or stop the natural process that dissolves bone tissue. The oral form of bisphosphonate has been the standard therapy for osteoporosis for many years. The dosing regimen is typically once a week but it can also be daily or monthly.
Why noncompliance is a problem
Regardless of the regimen, compliance is a serious problem. Some patients fail to comply due to the oral medication’s side effects, which can include difficulty swallowing, stomach upset and esophageal irritation. These side effects can be particularly troublesome for women with acid reflux. To avoid esophageal irritation, oral bisphosphonate must be taken on an empty stomach with plenty of water, and the patient must remain seated upright or standing for at least 30 minutes. The inconvenience of this requirement further decreases dosing compliance.
Many patients who try to follow the oral bisphosphonate regimen fail to take the doses correctly, either not fasting long enough before taking the medication or taking it with fluids other than water. This can affect the drug’s absorption and reduce its effectiveness.
The most common side effects of intravenous bisphosphonate include fever, headache, and pain in muscles, bones and joints. Symptoms can be eased with over-the-counter painkillers and usually resolve within three or four days of onset. A rare side effect is osteonecrosis of the jaw. To reduce the incidence of this condition, patients undergo a dental exam prior to infusion.
Who should not take intravenous bisphosphonate
Contraindications for intravenous bisphosphonate are identical to those for the oral form. Patients with renal insufficiency and low blood calcium are not good candidates, nor are people taking zoledronic acid for cancer therapy. Patients with low vitamin D and/or calcium levels can be treated with supplements for a period of about one month prior to infusion to boost these levels.
Study results
In a three-year study involving 7,700 women, zoledronic acid reduced the risk of vertebral and hip fracture by 71 percent and 41 percent, respectively, while significantly increasing bone mineral density, according to the drug’s manufacturer, Novartis Pharmaceuticals Corporation. Women who participated in the double-blind study took 1,000 to 1,500 mg of calcium and 400 to 1,200 IU of vitamin D daily.
Post-menopausal women should be reminded that regular exercise and a healthy diet are part of a holistic approach to good bone health.
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