Quantification of doripenem in human plasma and peritoneal fluid by high-performance liquid chromatography with ultraviolet detection

A simple and rapid HPLC method that includes ultrafiltration to remove plasma and peritoneal fluid protein was developed to determine doripenem concentrations in human plasma and peritoneal fluid. Doripenem was stabilized by immediate mixing of the plasma or peritoneal fluid with 1 M 3-morpholinopropanesulfonic acid buffer (pH 7.0) (1:1). Doripenem and an internal standard were detected by measuring their ultraviolet absorbance at 300 nm. The calibration curves for doripenem in human plasma and peritoneal fluid were linear from 0.05 to 100 μg/mL. For plasma, both the intra- and the interday precision were less than 3.41% (CV), and the accuracy was between 97.4 and 101.7% above 0.05 μg/mL. For peritoneal fluid, the intra- and the interday precision were less than 2.98% (CV), and the accuracy was between 94.4 and 103.9% above 0.05 μg/mL. The limit of detection was 0.02 μg/mL in both plasma and peritoneal fluid. The assay has been applied to the therapeutic drug monitoring of doripenem in both plasma and peritoneal fluid.