A Case of Inadvertent Overdose of Vosoritide Injection in a Three-Month-Old Infant With Achondroplasia

Vosoritide, a recombinant C-type natriuretic peptide analog that antagonizes fibroblast growth factor receptor 3 (FGFR3) signaling, is recommended for early initiation in infants with achondroplasia. However, clinical safety data for infants under six months remain limited, and concerns persist regarding its potential to induce symptomatic hypotension. We present a case of a three-month-old female infant with genetically confirmed achondroplasia (FGFR3 p.Gly380Arg) who accidentally received an inadvertent double dose of vosoritide (0.24 mg; 53 μg/kg) during home self-injection therapy. This patient remained completely asymptomatic, exhibiting no signs of hypotension, lethargy, or facial pallor during home monitoring. While findings from a single patient cannot definitively establish safety, the complete absence of adverse reactions after an accidental overdose suggests substantial inter-individual variability in hemodynamic sensitivity to vosoritide during early infancy. This clinical observation provides insights into the drug's tolerability profile in young infants.