Treatment with alendronate plus calcium,alendronate alone,or calcium alone for postmenopausal low bone mineral density

ABSTRACT

Objective: Bisphosphonates such as alendronate are widely used for postmenopausal osteoporosis. Supplemental calcium is also generally recommended. This trial directly compares alendronate to supplemental calcium and examines the effect of calcium supplementa­tion on alendronate treatment.

Methods: This 2-year, randomized, double-blind, multicenter trial enrolled healthy, postmenopausal women with low bone mineral density (BMD). Patients with a dietary calcium intake ≥?800?mg/day received daily vitamin D 400?IU and alendronate 10?mg/calcium-placebo, alendronate 10?mg/elemental calcium 1000?mg, or alendronate-placebo/calcium 1000?mg (2:2:1). Endpoints included BMD, bone turnover markers (BTMs), and adverse events.

Results: Randomized patients (N = 701) were an average of 20.4 years postmenopausal. After 24 months, increases in lumbar spine BMD differed significantly between patients receiving calcium alone (0.8%) and either alendronate alone (5.6%) or alendronate + calcium (6.0%) (?p < 0.001). Significant differences were also seen at the trochanter and femoral neck (?p < 0.001). BTMs were significantly lower with alendronate-containing treatments than calcium alone (?p < 0.001). Addition of calcium supplementation to alendronate did not signif­icantly increase BMD compared to alendronate alone (?p = 0.29 to 0.97), but did result in a statistically significant, though small, additional reduction in urinary NTx. Adverse events were similar among treatment groups. Limitations include no assessment of vitamin D levels and a discontinuation rate of approximately 30%, although discontinuation rates were similar among treatment groups.

Conclusions: In postmenopausal women with a daily intake of ≥?800?mg calcium and 400?IU vitamin D, 24-month treatment with alendronate 10?mg daily with or without calcium 1000?mg resulted in significantly greater increases in BMD and reduction of bone turnover than supplemental calcium alone. Addition of supplemental calcium to alendronate treatment had no effect on BMD and resulted in a small, though statistically significant, additional reduction in NTx.