RESUMO
A simple and sensitive high-performance liquid chromatographic micro-method for the determination of roxithromycin in human plasma and urine is described. A dichloromethane extract of the sample was chromatographed on a C18 reversed-phase column with acetonitrile-83 mM ammonium acetate-methanol (55:23:22, v/v) adjusted to pH 7.5 with acetic acid as the mobile phase. Roxithromycin and the internal standard, erythromycin, were detected by dual coulometric electrodes operated in the oxidative screen mode. The applied cell potential of the screen electrode was set at +0.7 V and the sample electrode at +0.9 V. The intra- and inter-assay coefficients of variation were less than or equal to 7.0%. The detection limit (signal-to-noise ratio = 3) was 0.1 microgram/ml for both plasma and urine. A study of drug stability during sample storage at 4, 20 and 37 degrees C showed no degradation of roxithromycin. The method is convenient for clinical monitoring and pharmacokinetic studies.
Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Leucomicinas/análise , Aminoglicosídeos , Antibacterianos/sangue , Antibacterianos/urina , Eletroquímica , Eritromicina/sangue , Eritromicina/urina , Humanos , Leucomicinas/sangue , Leucomicinas/urinaRESUMO
A sensitive and rapid high-performance liquid chromatographic method for the determination of ceftriaxone in human plasma and urine is described. A C18 reversed phase column is used; the mobile phase comprises water-methanol-triethylamine (750:250:4v/v/v) adjusted to pH 3 with orthophosphoric acid. Quantitation is performed at 270 nm with cefazolin as the internal standard. This method involves precipitation of proteins from fluids with acetonitrile followed by extraction of endogenous compounds with chloroform and injection of the upper aqueous phase on to the chromatograph. Relative standard deviations for between-day and within-day assays are 6.2%. The detection limit is 0.5 microg(-1) in plasma and urine. Studies of drug stability during sample storage, sample pretreatment and chromatography showed no degradation of ceftriaxone or of the internal standard. The method is convenient for clinical monitoring and for pharmacokinetic studies.
