A sensitive assay method of furosemide in plasma and urine by high-performance liquid chromotography

A sensitive assay method of furosemide in plasma and urine by high-performance liquid chromatography (HPLC) is described. The minimum measurable concentrations of furosemide in plasma and urine were 0.2 and 5.0 microgram/ml, respectively; whereas the coefficients of variation of furosemide levels were found to be 7.8% for plasma and 2.0% for urine. These are within the acceptably low limits. Hence, the present method of furosemide is sensitive, reproducible, and accurate for therapeutic drug monitoring. The significance of this HPLC assay method is discussed.