A whole blood microsampling furosemide assay: development, validation and use in a pediatric pharmacokinetic study.

Furosemide is a commonly used diuretic for the treatment of edema. The pharmacokinetics of furosemide in neonates as they mature remains poorly understood. Microsampling assays facilitate research in pediatric populations. We developed and validated a liquid chromatography-tandem mass spectrometry method for the quantitation of furosemide in human whole blood with volumetric absorptive microsampling (VAMS) devices (10 μl). Furosemide was stable in human whole blood VAMS under the study's assay conditions. This work established stability for furosemide for 161 days when stored as dried microsamples at -78°C. This method is being applied for the quantitation of furosemide in whole blood VAMS in an ongoing prospective pediatric clinical study. Representative clinical data are reported.