Zoledronic acid versus alendronate in the treatment of children with osteogenesis imperfecta: A 2-year clinical study

Objective: Bisphosphonates have been demonstrated to increase the bone mineral density (BMD) of osteogenesis imperfecta (OI) patients. We aimed to compare the efficacy and safety of intravenous zoledronic acid and oral alendronate in patients with OI. Methods: A total of 161 patients with OI ranging from 2 to 16 years old were included and randomized at a 2:1 ratio to receive either weekly oral alendronate (ALN) 70 mg or a once-yearly infusion of zoledronic acid (ZOL) for 2 years. The primary endpoints were percentage change from baseline in lumbar spine (LS) BMD and change in Z-scores of LS BMD. Results: A total of 136 patients with OI completed the 2-year clinical study, 90 of whom were assigned to receive ALN, while 46 received ZOL treatment. The percentage change in LS BMD was 60.01 ± 7.08% in the ALN group and 62.04 ± 5.9% in the ZOL group (P =.721). The corresponding BMD Z-score increased by 0.50 ± 0.05 in the ALN group and 0.71 ± 0.06 in the ZOL group (P =.013). ZOL was superior to ALN in reducing the clinical fracture rate (hazard ratio, 0.23; 95% confidence interval, 0.118 to 0.431). There was no difference in the incidence of severe side effects between the two groups. Conclusion: A once-yearly 5 mg infusion of ZOL and weekly oral ALN had similar effects in increasing BMD and reducing bone resorption in children and adolescents with OI. ZOL was superior to ALN in reducing the clinical fracture rate. Abbreviations: 25OHD = 25-hydroxyvitamin D ALN = alendronate ALP = alkaline phosphatase β-CTX = cross-linked C-telopeptide of type I collagen BMD = bone mineral density BP = bisphosphonate FN = femoral neck LS = lumbar spine OI = osteogenesis imperfecta SAE = severe adverse event ZOL = zoledronic acid.