Development Of LC/MS/MS Methods For Simultaneous Determination Of Two Alkaline Drugs In Human Plasma And Their Applications

Objective Two rapid, sensitive and specific methods for simultaneous quantitative analyses of two alkaline drugs in plasma will be developed and validated by liquid chromatography/tandem mass spectrometry in this thesis. The methods will be applied to pharmacokinetic studies.Methods Simultaneous determination of amantadine and chlorpheniramine in human plasma by liquid chromatography-tandem mass spectrometry. Samples spiked with the analytes and the internal standard, diphenhydramine, were processed using liquid-liquid extraction. The extract was chromatographed on a Zorbax SB-C₁₈ column. The mobile phase consisted of methanol-water-formic acid (80 : 20 : 0.5, v/v/v), at a flow rate of 0.60 mlAnin. A tandem mass spectrometer equipped with atmospheric pressure chemical ionization source was used as the detector and was operated in positive ion mode. Selected reaction monitoring (SRM) using the precursor/product ion combinations of m/z 152 → m/z 135 and m/z 275 → m/z 230 were used to quantify amantadine and chlorpheniramine, respectively. Simultaneous determination of loratadine and its active metabolite desloratadine in human plasma by liquid chromatography-tandem mass spectrometry. The analytes were extracted from plasma samples by liquid-liquid extraction, separated on a Zorbax SB-C₁₈ column and detected by tandem mass spectrometry with a electrospray ionization interface. Diphenhydramine was used as the internal standard. Multi reaction monitoring (MRM) using the precursor/product ion combinations of m/z 383 → m/z 267 and m/z 311 → m/z 259 were used to quantify loratadine and desloratadine, respectively.Results The linear concentration ranges of the calibration curves for amantadine and chlorpheniramine were 2.0-800 ng/ml and 0.1-40.0 ng/ml, respectively. The method has a lower limit of quantification (LLOQ) of 2.0 ng/ml and 0.1 ng/ml for amantadine and chlorpheniramine, respectively. The method has a lower limit of quantification of 0.01 ng/ml for both loratadine and desloratadine. The standard calibration curves were linear in the concentration ranges of 0.01-10.0 ng/ml both for loratadine and desloratadine in human plasma.