Reversed-phase high-performance liquid chromatography (RP-HPLC) assays using ultraviolet (UV) absorbance detection have been developed for the determination of a new @entity2893 antibiotic I in @entity1 plasma and urine. A column-switching technique is employed in the HPLC methods to perform on-line extraction and separation for each sample. Each plasma sample is thawed, centrifuged, stabilized, and then injected onto an in-line reversed-phase extraction column using a @entity1042 (8%)/phosphate buffer, pH 6.5. After 3 min, the analytes are back-flushed off the extraction column with a mixture of @entity1626 (5.5%) and @entity1042 (10%)/ @entity1391 buffer (pH 6.5) for 3 min onto a BDS Hypersil 3 microm @entity6173 (100 x 4.6 mm i.d.) analytical column. The sample preparation and HPLC conditions for the urine assay are similar to the plasma assay, except that a CN extraction column is used. Both assays are specific with respect to endogenous material and the major metabolite II, and both are linear over the concentration range of 0.25-50, and 2-200 microg/ml, respectively. The assays were successfully applied to a clinical dose-ranging study. One limitation of the on-line extraction method is that the extraction column needs to be replaced regularly every 100-150 plasma samples and every 200-300 urine samples. Subsequently, the urine method was modified to an ion-pair HPLC assay for the simultaneous determination of both the antibiotic I and its metabolite II.

Direct-injection HPLC assay for the determination of a new @entity2893 antibiotic in XXXX plasma and urine.

@entity1 :: ('9606', 'Species') :: ['human'] @entity1042 :: ('MESH:D000432', 'Chemical') :: ['methanol'] @entity1626 :: ('MESH:C032159', 'Chemical') :: ['acetonitrile'] @entity6173 :: ('27241', 'Gene') :: ['C18'] @entity1391 :: ('CHEBI:26020', 'Chemical') :: ['phosphate'] @entity2893 :: ('CHEBI:46765', 'Chemical') :: ['carbapenem']
@entity1 :: (9606,Species) :: ['human']
