The effect of the lower dose of FOSAVANCE (alendronate 70 mg/ vitamin D3 2800 IU) plus an additional 2800 IU Vitamin D3 for a total of 5600 IU (the amount of vitamin D3 in the higher dose of FOSAVANCE) once weekly was demonstrated in a 24-week, extension study that enrolled 619 osteoporotic post-menopausal women.