Once-a-week formulations of alendronate (Fosamax) in 35- and 70-mg tablets have now been approved by the FDA and are being heavily promoted for prevention and treatment of postmenopausal osteoporosis. A new formulation of risedronate (Actonel) for once-a-week use is under development and may be available next year.

The bisphosphonate risedronate (Actonel - Procter & Gamble) was recently approved by the FDA in a 150- mg once-monthly oral tablet for prevention and treatment of postmenopausal osteoporosis. The drug is also available for the same indication in 5-mg daily, 35-mg weekly and 75-mg twice-monthly tablets.

A new enteric-coated delayed-release formulation of risedronate (Atelvia – Warner Chilcott) has been approved by the FDA for treatment of postmenopausal osteoporosis. Unlike immediate-release risedronate (Actonel) and all other oral bisphosphonates, which must be taken after an overnight fast and at least 30 minutes before eating breakfast, the new formulation is taken immediately after breakfast with at least 4 ounces of water. Then the patient must remain upright for at least 30 minutes.CLINICAL TRIAL — Approval of Atelvia was based on a 52-week non-inferiority study in more than 900...

A once-weekly 35-mg oral formulation of the bisphosphonate risedronate (Actonel) has been approved by the FDA for prevention and treatment of postmenopausal osteoporosis. A once-weekly formulation of alendronate (Fosamax) was approved last year (Medical Letter 2001; 43:26). Bisphosphonates bind to the mineral surface of bone and decrease osteoclast activity, inhibiting the resorption phase of the bone turnover cycle. These drugs are not metabolized and remain bound to bone for several weeks.

Zoledronic acid (Reclast - Novartis) is the first bisphosphonate approved by the FDA for once-yearly intravenous (IV) treatment of osteoporosis in postmenopausal women. Reclast is also approved for treatment of Paget's disease. Another IV formulation of zoledronic acid (Zometa) is approved for treatment of hypercalcemia of malignancy, multiple myeloma and bone metastases from solid tumors.

Long-term use of bisphosphonates for prevention and treatment of osteoporosis has been associated with osteonecrosis of the jaw, atypical fractures of the femur, and possibly esophageal cancer. So for how long should patients take them?

The FDA has approved romosozumab-aqqg (Evenity – Amgen), a sclerostin inhibitor, for once-monthly subcutaneous (SC) treatment of osteoporosis in postmenopausal women who are at high risk for fracture (history of osteoporotic fracture or multiple risk factors for fracture) or who have failed or cannot tolerate other drugs for this indication. Romosozumab is the first sclerostin inhibitor to be approved in the US and the third drug for treatment of postmenopausal osteoporosis that stimulates bone formation; the parathyroid hormone (PTH) receptor agonists abaloparatide (Tymlos) and...

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) 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.

Use of alendronate (Fosamax), estrogen and other drugs for prevention and treatment of osteoporosis (Medical Letter, 38:1, 1996) has been accompanied by widespread availability of bone density screening tests, not only in doctors offices and hospitals, but even in retail stores. Bone densitometry provides a quantitative measurement of bone mineralization that can be used to predict the risk of osteoporotic fractures.