Determination of fexofenadine in human plasma and urine by liquid chromatography–mass spectrometry

Abstract A sensitive method was developed to determine fexofenadine in human plasma and urine by HPLC–electrospray mass spectrometry with MDL 026042 as internal standard. Extraction was carried out on C 18 solid-phase extraction cartridges. The mobile phases used for HPLC were: (A) 12 m M ammonium acetate in water and (B) acetonitrile. Chromatographic separation was achieved on a LUNA CN column (10 cm×2.0 mm I.D., particle size 3 μm) using a linear gradient from 40% B to 60% B in 10 min. The mass spectrometer was operated in the selected ion monitoring mode using the respective MH + ions, m / z 502.3 for fexofenadine and m / z 530.3 for the internal standard. The limit of quantification achieved with this method was 0.5 ng/ml in plasma and 1.0 ng in 50 μl of urine. The method described was successfully applied to the determination of fexofenadine in human plasma and urine in pharmacokinetic studies.