The FDA, which had previously approved intravenous (IV) administration of 5 mg of zoledronic acid (Reclast – Novartis) once a year for treatment of postmenopausal osteoporosis (Med Lett Drugs Ther 2007; 49:89), has now approved the same dose for use once every 2 years to prevent osteoporosis in postmenopausal women with osteopenia.

Clinical Studies – In an unpublished study summarized in the package insert, 224 women with osteopenia ≤5 years after menopause were given an IV infusion of zoledronic acid 5 mg or placebo; 2 years later, total hip bone mineral density (BMD) had increased by 2.6% with the drug and decreased by 2.1% with placebo. Among 357 osteopenic women >5 years after menopause, hip BMD 2 years after one IV dose of zoledronic acid increased by 2.1% and decreased by 1.0% with placebo. Both of these differences from placebo were statistically significant. Similarly significant increases occurred in vertebral BMD. No data are available on the incidence of hip or vertebral fractures in these women, but zoledronic acid once a year for treatment of osteoporosis has been shown to decrease the incidence of such fractures.

Adverse Effects — An acute-phase reaction including fever, flu-like symptoms, headache, arthralgia and myalgia can occur with IV administration of zoledronic acid; symptoms usually subside within a few days. Renal damage can occur after a single dose, especially with concomitant use of other nephrotoxic drugs, including nonsteroidal anti-inflammatory drugs (NSAIDs). Jaw osteonecrosis has occurred rarely. Whether long-term use of bisphosphonates, which interfere with bone remodeling, could increase the incidence of long-bone fractures remains to be established. None of these events, except for acutephase reactions, occurred during the clinical trial, according to the manufacturer.

Cost – The cost of one 5-mg injection of Reclast is about $1200 for the drug alone.

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Ibandronate (Boniva - Roche) is the first bisphosphonate approved by the FDA for intravenous (IV) treatment of osteoporosis in postmenopausal women. It is given as a bolus injection once every 3 months. Ibandronate is also available as an oral once-a-month 150-mg tablet and as a daily 2.5-mg tablet.

A 10-year study of daily oral alendronate (Fosamax) and a 7-year study of daily oral risedronate (Actonel) indicate that both drugs maintained increases in bone mineral density (BMD) and decreases in markers of bone remodeling throughout the study period. Both drugs are now more commonly taken once weekly. Available data are insufficient to compare fracture rates with alendronate and risedronate, and fracture rates are considered the most important endpoint in osteoporosis studies. Recent reports of severe pain and jaw osteonecrosis with these drugs are disturbing.

Ibandronate (Boniva - Roche/GSK), a new oral bisphosphonate, was recently approved by the FDA in a once-monthly formulation for prevention and treatment of postmenopausal osteoporosis. The drug was initially approved in 2003 as a daily tablet, but was not marketed. An intravenous formulation for use once every 3 months is under investigation.

The FDA has approved a new low-dose estrogen patch (Menostar - Berlex) for prevention of osteoporosis in postmenopausal women. Unlike other estrogen patches, it is not approved for treatment of hot flashes or other menopausal symptoms. Promotional material from the manufacturer suggests that this low dose of estrogen could prevent osteoporosis without some of the adverse effects of higher doses.