Safety and Tolerability of Intravenous Bisphosphonate Infusion to Improve Bone Mineral Density in Children with Spinal Muscular Atrophy at a Tertiary Care Hospital in India: An Observational Retrospective Study

Abstract

Background: Children with spinal muscular atrophy (SMA) have significantly reduced bone mineral density (BMD) compared to other neuromuscular disorders, predisposing them to frequent fractures. Despite this, bone health is frequently under-researched and under-managed in SMA care. Intravenous (IV) bisphosphonates, particularly zoledronate, reportedly improve BMD and reduce fracture risk in other disorders, with a favorable safety profile. This study aimed to evaluate the safety and tolerability of IV zoledronate in SMA type 2 pediatric patients in a tertiary care hospital. Materials and Methods: An observational retrospective study was conducted between June 2022 and July 2024. Twenty-two patients with SMA type 2 had their case notes from the SMA clinic retrospectively reviewed; of these, 8 patients (aged 5-17 years) with SMA type 2 had low BMD (Z <-2.5 on DEXA scan) who met the fitted inclusion criteria and received 0.05 mg/kg body weight of IV zoledronate every 6 months. Patients were monitored for adverse events (AEs), fractures, and clinical outcomes. Results: Fifteen infusions were administered in total; no serious Adverse Events (AEs) or adverse drug reactions (ADR) were observed. Grade I fever in 50% (3/6) of the females and infusion-related grade II pain in 87.5% (7/8) of the patients were observed, which resolved within 24 h with paracetamol. No patient required re-admission. Laboratory parameters and motor scales remained stable and no fractures occurred during the study period. Conclusion: IV zoledronate is safe and well-tolerated in children with SMA type 2 in their multidisciplinary management.