Safety and efficacy of a 1-year treatment with zoledronic acid compared with pamidronate in children with osteogenesis imperfecta

Pamidronate (PAM) infusion is the standard treatment in children with osteogenesis imperfecta (OI). Zoledronic acid (ZOL) is a bisphosphonate with higher potency and faster intravenous infusion, but its efficacy and safety has not been established for OI patients. We report an open-label, prospective, and randomized clinical analysis to study the safety and efficacy of ZOL compared with PAM in 23 children with OI. They were selected to receive PAM (PAM group), 1 mg/kg/day, over 2 days or ZOL (ZOL group), 0.025-0.05 mg/kg/day, over 2 days every 3-4 months according to their ages, during a 1-year follow-up. They were observed for clinical and biochemical parameters, side effects, bone mineral density (BMD), and fracture rate. After treatment, the PAM and ZOL groups average lumbar spine (LS) BMD increased by 51.8% (p=0.053) and 67.6% (p=0.003), respectively. Parallel improvement was seen in LS Z-score in the PAM and ZOL groups, with scores of -5.3 to -3.8 (p=0.032) and -4.8 to -2.3 (p=0.007), respectively. LS Z-score for the ZOL group at the end of treatment was higher compared with the PAM group but only a borderline significance (p=0.053). The total alkaline phosphatase (AP) in the ZOL group significantly decreased from baseline at third and fourth infusion (p=0.032). Mild side effects were similar in both groups, but no severe clinical symptoms were reported. In conclusion, the present study shows that the use of ZOL in the dosage and period studied was safe and efficient to promote a clinical and densitometric improvement, similarly to PAM. Further studies are needed to establish optimal dosing and long-term safety.