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

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,, solid-phase extraction cartridges. The mobile phases used for HPLC were: (A) 12 mM ammonium acetate in water and (B) acetonitrile. Chromatographic separation was achieved on a LUNA CN column (10 cmx2,0 mm I.D, particle size 3 mum) 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 mul of urine. The method described was successfully applied to the determination of fexofenadine in human plasma and urine in pharmacokinetic studies. (C) 2002 Elsevier Science B.V. All rights reserved.