ABSTRACT
To establish a sensitive and specific method for simultaneous determination of gestodene, etonogestrel and ethinylestradiol in plasma by LC-MS/MS, plasma samples were extracted and derivatized before injection. An ESI ion source was used and operated in the positive ion mode with multiple reaction monitoring (MRM). Norgestrel was chosen as internal standard and performed on a C18 (100 mm x 2.1 mm, 5 microm) column. The concentrations of gestodene, etonogestrel and ethinylestradiol were measured, using step-gradient mobile phase and step-gradient flow rate. The method was validated over the concentration range of 0.1-20 ng x mL(-1) for gestodene and etonogestrel and 0.01-2 ng x mL(-1) for ethinylestradiol, and showed excellent linearity. The intra- and inter-assay accuracy and precision were below 10.0% and recovery was 93.6%-110.9% over the three concentration levels evaluated. The method was applied in pharmacokinetic study of the compound gestodene patch and the compound etonogestrel patch in rabbits. The LC-MS/MS method was selective, accurate and sensitive, especially the LOQ were 100 pg x mL(-1) for gestodene and etonogestrel and 10 pg x mL(-1) for ethinylestradiol. The method was successfully applied in pharmacokinetic study for contraceptives.
Subject(s)
Animals , Rabbits , Chromatography, Liquid , Desogestrel , Blood , Pharmacokinetics , Ethinyl Estradiol , Blood , Pharmacokinetics , Norpregnenes , Blood , Pharmacokinetics , Sensitivity and Specificity , Spectrometry, Mass, Electrospray IonizationABSTRACT
<p><b>AIM</b>To establish a sensitive and specific method to simultaneous determination of pseudoephedrine and chlorpheniramine in human plasma.</p><p><b>METHODS</b>Pseudoephedrine and chlorpheniramine were extracted from alkaline plasma with t-butyl methyl ether as the base form, and were back-extracted into 1.5% hydrochloride solution. The two drugs were simultaneous determined by RP-HPLC with ultraviolet detection at 200 nm, using dextromethorphan as internal standard. A C18 column (250 mm x 46 mm ID) and a mobile phase containing acetonitrile-water-triethylamine (46:54:0.2, containing 10 mmol x L(-1) sodium dodecyl sulfate (SDS) and 60 mmol x L(-1) NaH2 PO4, adjusted pH to 2.6 with H3PO4) were used.</p><p><b>RESULTS</b>The limit of quantification was 10.0 and 0.5 microg x L(-1), the linear range was 1.5 - 0.01 mg x L(-1) and 75 - 0.5 microg x L(-1), for pseudoephedrine and chlorpheniramine, respectively. The within-day and between-day RSD were less than 12.4%, and the average recovery was between 97.3% - 109.4%.</p><p><b>CONCLUSION</b>The method was sensitive, specific, simple, and suitable for drug level monitoring in clinical pharmacokinetic study.</p>