Development and Validation of a Novel Liquid Chromatography-Tandem Mass Spectrometry Method for the Quantification of Isavuconazole in Human Plasma and Its Application to a Pharmacokinetic Study

• Developed a rapid and sensitive LC-MS/MS method for isavuconazole quantification in human plasma with a lower limit of quantification of 5 ng/mL. • Validated the method according to FDA guidelines, achieving high precision (RSD < 9.2%) and accuracy (RE within ±4.5%). • Successfully applied the method to a pharmacokinetic study in healthy Chinese volunteers, providing key PK parameters. • The method is suitable for therapeutic drug monitoring and clinical pharmacokinetic studies of isavuconazole.