High-performance liquid chromatographic determination of the penem antibiotic (5R,6S)-2-aminomethyl-6-[(1R)-hydroxyethyl]-2-penem-3-carboxylic acid in human plasma and urine

High-performance liquid chromatographic methods for the determination of (5R,6S)-2-aminomethyl-6-[(1R)-hydroxyethyl]-2-penem-3-carboxylic acid in plasma and urine have been developed, validated and applied to clinical samples. After addition of another penem, (5R,6S)-2-aminoethyl-6-[(1R)-hydroxyethyl]-2-penem-3-carboxylic acid, as an internal standard, plasma proteins are precipitated with a saturated solution of ammonium sulphate. A portion of the supernatant is injected on to a reversed-phase column (RP 8–10μm) that is eluted with pH 6 phosphate buffer. The urine assay entails a 25-fold dilution with pH 6 buffer and addition of the internal standard prior to injection. The detector response at 320 nm is a linear function of concentration over the ranges 1.6–410 μmol/l (0.4–100 μg/ml) and 41–1025 μmol/l (10–250 μg/ml) for the plasma and urine assays, respectively. These methods have proved to be suitable for pharmacokinetic investigations in man.