Efficacy of risedronate with cholecalciferol on 25-hydroxyvitamin D level and bone turnover in Korean patients with osteoporosis

Background We performed a randomized, double-blind, prospective, 16-week clinical trial to evaluate the efficacy and safety of risedronate with and without cholecalciferol on 25-hydroxyvitamin D [25(OH)D] levels and bone markers in Korean patients with osteoporosis. Methods We randomly assigned 164 adults with osteoporosis to one of two treatment groups: weekly risedronate 35 mg and cholecalciferol 5600 IU combined in a single pill (RSD+) or weekly risedronate 35 mg alone (RSD). We measured serum levels of 25(OH)D, parathyroid hormone (PTH), and bone markers and performed muscle function tests, at baseline and after 16 weeks of treatment. Results After 16 weeks of treatment, mean serum 25(OH)D increased significantly from 39·8 to 70·8 nmol/l in the RSD+ group and declined significantly from 40·5 to 35 nmol/l in the RSD group. Although both treatment groups had significant increases in serum PTH over baseline during the study, the RSD group had a significantly larger increase than the RSD+ group (13·6 vs 4·8 ng/l; P = 0·0005). In both groups, serum bone-specific alkaline phosphatase (BSAP) and C-terminal telopeptide (CTX) declined rapidly; there were no significant differences between groups. There was also no significant difference between groups in lower-extremity function tests. The overall incidence of clinical adverse events was not significantly different between groups. Conclusion In patients with osteoporosis, a once-weekly pill of risedronate and cholecalciferol provided equivalent antiresorptive efficacy to risedronate alone in terms of bone turnover and improved 25(OH)D level over a 16-week treatment period without significant adverse events.