Response to zolendronic acid in children with type III osteogenesis imperfecta

Osteogenesis imperfecta (OI) is a common genetic disorder that manifests with intrauterine or pre- or postnatal fractures, blue sclera, and deafness. Various treatments for the management of OI have been tried, of which bisphosphonates (BPs) seem to have the maximum benefit in reducing fracture rate and improving bone density. Zolendronic acid is a newer BP tried for several bone diseases, mainly in adults. The objective of our analysis was to study the response to zolendronic acid in children with type III OI. The case records of subjects with type III OI receiving zolendronic acid in the past 3 years between February 2006 and March 2009 were analyzed. Relevant details were recorded on a predesigned chart. Subjective improvement, reduction in number of fractures, and the DEXA scan Z-score were used to judge improvement. Five OI type III cases were followed up in the Genetic clinic. Presentation was from neonatal period to 7 years of age; M:F ratio was 3:2. Average duration of therapy given was 20.4 months. Improvement was noted in all patients, in the form of reduction in frequency of fractures (P = 0.002) and increase in bone density on DEXA scan (P = 0.01). Side effects noted were flu-like symptoms and myalgia. No clinical problems due to hypocalcemia were noted in any of the patients. Thus, zolendronic acid is seen as a safe and effective BP in type III OI children. The exact dose for optimal benefit is yet to be determined. The long-term effects of newer BPs need further long-term trials.