A simple and specific liquid chromatography-atmospheric pressure chemical ionization-mass spectrometry (LC-APCI-MS) assay method has been developed and fully validated for the simultaneous quantification of cefixime (CX) and clavulanic acid (CA) in human plasma. Analytes and internal standard were extracted from human plasma by a solid phase extraction technique using a Sam prep (3 mL, 100 mg) extraction cartridge. The extracted samples were chromatographed on a reverse phase C18 column using a mixture of methanol : acetonitrile : 2 mM ammonium acetate (pH 3.5) (25 : 25 : 50, v/v/v) as the mobile phase at a flow rate of 0.8 mL/min. Quantification of the analytes were carried out using single quadrupole LC-APCI-MS through selected ion monitoring at m/z 452 and 198, respectively, for CX and CA. The assay was linear over the concentration range of 0.05-10.0 and 0.1-10.0 μg/mL, respectively, for CX and CA. The mean plasma extraction recoveries of the CX and CA were found to be 95.20-96.27% and 94.67-95.58%, respectively. The method was successfully applied for the determination of pharmacokinetics of CX and CA after oral administration of single dosage CX/CA (200/125 mg) pill to the humans (n = 12).

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 (3 mL, 100 mg) extraction cartridge. The extracted samples were chromatographed on a reverse phase C18 column using a mixture of methanol: acetonitrile: 2 mM ammonium acetate (pH 3.5) (25:25:50, v/v/v) as the mobile phase at a flow rate of 0.8 mL/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 (500/125 mg) pill to healthy male volunteers (n=12) was measured. Area under plasma concentration–time curve from 0 to 12 h (AUC0–12 h) and 0 h extrapolated to infinity (AUC0−∞) were calculated. The ratio of AUC0–12 h/AUC0−∞ was found to be >85% for all the subjects, as recommended by the FDA guidelines.

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