Simultaneous pharmacokinetic assessment of cefadroxil and clavulanic acid in human plasma by LC–MS and its application to bioequivalence studies

Abstract

A simple, rapid and selective liquid chromatography–atmospheric pressure chemical ionization–mass spectrometry (LC–APCI–MS) assay method has been developed and fully validated for the simultaneous quantification of cefadroxil (CF) and clavulanic acid (CA) in human plasma. Analytes and internal standard (IS) were extracted from human plasma by solid-phase extraction (SPE) technique using Sam prep (3mL, 100mg) extraction cartridge. The extracted samples were chromatographed on a reverse phase C18 column using a mixture of methanol: acetonitrile: 2mM ammonium acetate (pH 3.5) (25:25:50, v/v/v) as the mobile phase at a flow rate of 0.8mL/min. Quantification of the analytes and IS were carried out using single quadrupole LC–APCI–MS through selected-ion monitoring (SIM) at m/z 362 and m/z 198, for CF and CA, respectively. Method validation was performed as per the FDA guidelines and the results met the acceptance criteria. Plasma concentration of CF and CA followed by the oral administration of CF/CA (500/125mg) pill to healthy male volunteers (n=12) was measured. Area under plasma concentration–time curve from 0 to 12h (AUC0–12h) and 0h extrapolated to infinity (AUC0−∞) were calculated. The ratio of AUC0–12h/AUC0−∞ was found to be >85% for all the subjects, as recommended by the FDA guidelines. Keywords: Cefadroxil, Clavulanic acid, LC–MS, APCI, Pharmacokinetics, Bioequivalence