Sirolimus for management of complex vascular anomalies - A proposed dosing regimen for very young infants.

Neonates with vascular anomalies causing airway compromise and other complications require early initiation of medical therapy. Sirolimus has emerged as a safe and effective treatment, but standard recommendations for dosing start at seven months. Guidelines are needed for dosing in very young infants, who have reduced hepatic metabolism of sirolimus. We present our experience treating six neonates (mean age 14.8 days) with complicated vascular anomalies. Standard dosing caused supratherapeutic levels in this population. Our modified dosing regimen has resulted in safe therapeutic concentrations. Properly dosed, sirolimus is a viable and potentially lifesaving option for neonates with severe morbidity from vascular anomalies.