Effects of combined treatment with calcitriol plus alendronate on bone mass and bone turnover in postmenopausal osteoporosis two years of continuous treatment

One hundred and twenty postmenopausal women with osteoporosis were enrolled into an open, controlled study of 24 months' duration, with the aim of evaluating the metabolic action and the effect on bone mineral density (BMD) of calcitriol (0.5 mu g/day), alendronate (10 mg/day) and combined treatment with alendronate (10 mg/day) + calcitriol (0.5 mu g/day). We also studied 30 patients treated with placebo (calcium 500 mg/day). BMD was measured by total body dual-energy x-ray absorptiometry (DPX-Lunar) as total body BMD and at different sites of interest including the spine, trunk, arms, legs and pelvis. BMD appeared to be significantly higher in the group of patients receiving combined therapy compared with the group treated with alendronate or calcitriol alone. In the placebo group, BMD decreased significantly. Depending on the skeletal regions in which BMD was measured (total body or selected areas), 15 to 23% of patients treated with calcitriol, 37 to 48% of patients treated with alendronate, and 69 to 78% of patients treated with alendronate + calcitriol, respectively, had a BMD increase greater than the lowest significant densitometric difference. In patients treated with alendronate, 24-hour urinary calcium and hydroxyproline levels fell significantly after 3 months, and alkaline phosphatase levels fell significantly after 6 months; these parameters remained unchanged in all patients on combined treatment. We concluded that combined treatment with calcitriol + alendronate was more effective than therapy with alendronate alone.