KCS

A rapid and enantioselective analytical method has been developed and validated for the determination of levo-cetirizine in human plasma using supercritical fluid chromatography-tandem mass spectrometry (SFC-MS/MS). The SFC system provides high-throughput and unique selectivity compared with high performance liquid chromatography (HPLC). The cetirizine enantiomers have been separated by CHIRAL PAK IE column (2.1 mm x 150 mm, 5 μm particle size) which was maintained at 50°C. The isocratic mobile phase was composed of (A) carbon dioxide and (B) methanol with 5% (v/v) water in the proportion of 55:45 (v/v) at a flow rate of 0.85 mL/min. A stable isotope labeled internal standard, cetirizine-D4 was used. The tandem mass spectrometry was performed on an electrospray ionization source operating under positive ion mode and the analytes were detected using multiple reaction monitoring. The mass transitions of cetirizine and cetirizine-D4 were m/z 388.8→201.1 and 393.3→201.1. Analytical conditions of supercritical fluid chromatography such as column temperature, modifier content, additive content and flow rate were optimized using fractional factorial design and response surface methodology. Sample preparation was performed by SPE using HLB cartridge with ammonium formate buffer (20 mM, pH 3.0) and methanol. The dextro- and levo-cetirizine were well separated with no interference from endogenous plasma constituents in only 3.5 minutes. The developed method was validated in terms of linearity, accuracy, precision, recovery, limit of detection (LOD) and limit of quantification (LOQ). This analytical method was successfully applied to the analysis of pharmacokinetic study samples after oral administration of cetirizine to healthy Korean volunteers.