A simple and rapid determination of biapenem in plasma by high-performance liquid chromatography

A simple, rapid and precise HPLC method using ultrafiltration to remove plasma protein was developed to determine biapenem concentrations in human plasma. Plasma was separated by centrifugation at 4 °C from blood collected in heparinized vacuum tubes, and biapenem was stabilized by immediate mixing the plasma with 1 M 3-morpholinopropanesulfonic acid (MOPS) buffer (pH 7.0) (1:1). Biapenem was detected by ultraviolet absorbance at 300 nm with no interfering plasma peak. The calibration curve of biapenem in human plasma was linear from 0.04 to 50 μg/mL. The limit of detection was 0.01 μg/mL, which was more than 40-fold lower than that of conventional plasma protein precipitation using ammonium sulfate. The assay has been clinically applied to pharmacokinetic studies in patients.