High-performance liquid chromatographic determination of nafazatrom in human plasma using fluorescence detection

A rapid, sensitive, and selective high-performance liquid chromatographic assay was developed for determination of the pyrazole derivative nafazatrom (Bay g 6575, NFZ) in human plasma. Separation was obtained using a normal-phase Si-60 column and a mobile phase of methylene chloride--methanol (90:10, v/v) containing 0.25% water. The fluorescence of NFZ was monitored at excitation and emission wavelengths of 232 and 362 nm, respectively. The recovery of NFZ extracted from plasma with methylene chloride was 109 +/- 5% (mean +/- S.D.) in the concentration range from 5.0 to 500 ng/ml. The assay was applied to the determination of plasma concentrations of NFZ following administration of the compound to patients in a Phase I clinical trial.