Therapeutic equivalence of alendronate 35 milligrams once weekly and 5 milligrams daily in the prevention of postmenopausal osteoporosis.

Objective: To evaluate the efficacy and safety of alendronate 35 mg once weekly compared with alendronate 5 mg daily in the prevention of osteoporosis.

Methods: We compared the efficacy and safety of treatment with alendronate 35 mg once weekly (n = 362) and alendronate 5 mg daily (n = 361) in a 1-year, double-blind, multicenter study of postmenopausal women (6 months or greater), aged 40-70 years, with lumbar spine and femoral neck bone mineral density T-scores between -2.5 and 1. The primary efficacy end point was the comparability of lumbar spine bone mineral density increases, defined by strict prespecified criteria.

Results: Mean increases in lumbar spine bone mineral density at 12 months were equivalent (difference between the alendronate 35-mg once-weekly group and the alendronate 5-mg daily group [90% confidence interval] at month 12 was -0.3% [-0.6, 0.1], well within the prespecified bounds of +/-1.0%). Bone mineral density increases at other skeletal sites and effects on bone turnover were also virtually identical for the two dosing regimens. Both treatment regimens were well tolerated, and the larger weekly unit dose was not associated with an increased frequency of upper gastrointestinal events.

Conclusion: Alendronate 35 mg once weekly is therapeutically equivalent to alendronate 5 mg daily and provides patients with greater dosing convenience, in addition to the proven efficacy of alendronate and good tolerability.