BackgroundWe compared the efficacy of a fixed dose combination of raloxifene 60 mg/vitamin D 800 IU to raloxifene 60 mg alone on vitamin D status, as indicated by change in serum 25-hydroxy-vitamin D (25[OH]D) levels.MethodsIn this 16-week, open-label, randomized, active controlled, multicenter clinical trial conducted in 4 university-affiliated hospitals in Korea, postmenopausal women aged 55 to 70 years with osteoporosis or osteopenia were randomly assigned in a 1:1 ratio to receive raloxifene 60 mg/cholecalciferol 800 IU combination therapy or raloxifene 60 mg monotherapy. Primary endpoint was change in serum 25(OH)D level from baseline to 16 weeks after the intervention.ResultsA total of 96 participants were randomly assigned to raloxifene/vitamin D combination therapy (N=49) and raloxifene monotherapy (N=47) groups. At week 16, serum 25(OH)D level increased from baseline, only in the raloxifene/vitamin D combination therapy group. Change in serum 25(OH)D level from baseline to week 16 was higher in the raloxifene/vitamin D combination therapy group (2.7±6.5 ng/mL) than in the raloxifene monotherapy (−1.7±6.2 ng/mL; P=0.0034) group. Proportions and number of adverse events (AEs) categorized by the System-Organ Class were not different between the groups. There was only one severe AE case (spondylolisthesis; raloxifene/vitamin D group), unlikely to be related to trial intervention.ConclusionsAmong postmenopausal women with osteoporosis or osteopenia, a fixed dose combination of raloxifene 60 mg/vitamin D 800 IU showed superior efficacy in elevating serum 25(OH)D levels compared with raloxifene 60 mg alone during 16 weeks of follow-up. The safety of raloxifene/vitamin D combination was comparable to raloxifene alone.