High-performance liquid chromatographic assay for meropenem in serum

High-performance liquid chromatographic procedures have been developed for the measurement of meropenem in serum. The separation was performed on an Ultrasphere XL-ODS analytical column (75 x 4.6 min I.D.). The mobile phase consisted of 10.53 mmol/l ammonium acetate-acetonitrile (95:5, v/v) (pH 4). The UV detection was at 298 nm. The quantitation limit both in serum and water was 0.25 micrograms/ml. The method was validated in serum and aqueous solution over the concentration range 0.25-50 micrograms/ml. The extraction recovery from serum spiked with meropenem was 99.7 +/- 3.4%. The intra- and inter-assay coefficients of variation were below 6%. Stored at -80 degrees C for three months at various concentrations in serum and in aqueous solution, meropenem did not reveal any appreciable degradation. After 24 h, it was also stable at 4 degrees C in serum, aqueous solution and supernatant of extraction but not at room temperature. The stability of the drug was also confirmed in serum after repeated freezing-thawing cycles at -80 degrees C on four consecutive days.