Correction of vitamin D insufficiency with combined strontium ranelate and vitamin D3 in osteoporotic patients

Objective: This study aims to investigate the efficacy and safety of oral fixed-dose combination of strontium ranelate 2 g/vitamin D-3 1000 IU daily vs strontium ranelate 2 g daily for correcting vitamin D insufficiency in osteoporosis. Design: A 6-month international, randomized, double-blind, parallel-group, phase 3 study. Methods: A total of 518 men and postmenopausal women aged >= 50 years with primary osteoporosis (T-score <= -2.5 S. D.) and serum 25-hydroxyvitamin D (25(OH) D) > 22.5 nmol/l were included. Patients were allocated to strontium ranelate 2 g/vitamin D-3 1000 IU daily (n=413) or strontium ranelate 2 g daily (n=105). The participants received calcium 1 g daily. The primary endpoint was serum 25(OH) D at last post-baseline evaluation during 3 months. Results: Both groups were comparable at baseline. Mean baseline of 25(OH) D was 44.1 +/- 14.6 nmol/l. After 3 months, the percentage of patients with 25(OH) D >= 50 nmol/l was higher with strontium ranelate/vitamin D3 vs strontium ranelate (84 vs 44%, P < 0.001; adjusted between-group odds ratio=6.7; 95% CI, 4.2-10.9). The efficacy of the fixed-dose combination on 25(OH) D was maintained at 6 months (86 vs 40%, P < 0.001). Mean 25(OH) D was 65.1 and 49.5 nmol/l, respectively, after 3 months and 66.9 and 45.4 nmol/l after 6 months. Physical performance improved in both groups. Falls were 17 and 20% in the strontium ranelate/vitamin D-3 and strontium ranelate groups respectively. Parathyroid hormone levels were inversely correlated with 25(OH) D. No clinically relevant differences in safety were observed. Conclusions: This study confirms the efficacy and safety of fixed-dose combination of strontium ranelate 2 g/vitamin D-3 1000 IU for correction of vitamin D insufficiency in osteoporotic patients.