Liquid-chromatographic assay of cefmenoxime in serum and urine

This is a simple, precise liquid-chromatographic procedure for determining cefmenoxime in patients' serum and urine. p-Anisic acid is used as the internal standard. Protein is precipitated from 0.5 mL of serum or dilute urine with 100 μL of perchloric acid. The clear supernate is injected directly onto a μ-Bondapak CN reversed-phase column. The mobile phase is acetate buffer, pH 3.8 (25 °C). The flow rate is 2.5 mL/min. Column effluent is monitored at 254 nm. Extraction recovery from serum averaged 74.6%. Calibration curves were linear from 0.5 mg/L, the lower limit of quantification, to 100 mg/L. We present cefmenoxime concentrations in serum from a patient being treated for pneumonia. The procedure was evaluated in the clinical setting to determine its applicability to the study of cefmenoxime pharmacokinetics in critically ill patients.