Study on Theraputic Drug Monitoring and Phamacokinetics of Isavuconazole in Children

The goal of this clinical trial is to learn the plasma concentration of isavuconazole in pediatric patients. It will also learn about the relationship of isavuconazole plasma concentrations to efficacy and safety in pediatric patients. The main questions it aims to answer are: What is the plasma concentration after using isavuconazole in pediatric patients? What is the effective range of plasma concentration of isavuconazole in pediatric patients? What is the safe range of plasma concentration of isavuconazole in pediatric patients? Researchers will measure the plasma concentration of isavuconazole to see whether it is appropriate. Participants will: Take drug isavuconazole as prescribed by the doctor; 1mL of blood is drawn 30min before the next dose.