The solvent extraction of flurazepam and its major metaboutes and their determination by polarography

Large-volume sample stacking of selected drugs of forensic significance by capillary electrophoresis

Large-volume sample stacking capillary electrophoresis (LVSS-CE) and conventional capillary electrophoresis (CE) are compared for the separation of drugs of significance to forensic and clinical analyses. LVSS-CE for cations requires the use of an electroosmotic flow (EOF) modifier in conjunction with polarity switching to effect on-column concentration of an analyte and its subsequent migration in the capillary. The run buffer consists of 0.05 mol dm(-3) disodium tetraborate adjusted to pH 2.2 with orthophosphoric acid, and the EOF modifier is 0.002 mol dm(-3) cetyltrimethylammonium bromide. CE investigations used an identical run buffer minus the EOF modifier. LVSS-CE and CE investigations used injection times of 30 s and 3 s, respectively. Both modes of capillary electrophoresis are compared in terms of their limits of detection, efficiency, resolution and reproducibility. LVSS-CE is also applied to the analysis of a spiked urine sample.

Simultaneous determination of flurazepam and its metabolites in human plasma by high-performance liquid chromatography

A sensitive isocratic high-performance liquid chromatographic method is described, which allows the precise and accurate quantification of flurazepam and four metabolites with a single determination. A pharmacokinetic study was performed on nine volunteers and the main pharmacokinetic data are reported. The method was used to demonstrate that monodesethylflurazepam and didesethylflurazepam are major metabolites in men. One more unidentified flurazepam metabolite was detected.

Simultaneous determination of flurazepam and five metabolites in serum by high-performance liquid chromatography and its application to pharmacokinetic studies in rats

A reversed-phase high-performance liquid chromatographic method is described which allows the quantification of flurazepam and five of its metabolites with a single, isocratic determination. In addition, it has the advantage of possessing a low detection limit and high precision. A 2 mm I.D. column was used to minimize sample size (50 microliter), increase sensitivity and reduce solvent consumption. The method was used to demonstrate that N-1-desalkylflurazepam, the major metabolite, has a short half-life in the rat in contrast to its prolonged life in humans.

Gas chromatographic determination of quazepam and two major metabolites in human plasma

Two rapid, sensitive, and specific gas chromatographic (GC) methods for the quantitative determination of quazepam (I), 7-chloro-5-(2-fluorophenyl-1,3-dihydro-1-(2,2,2-trifluoroethyl) -2H-1,4-benzodiazepine-2-thione, and its major active plasma metabolites, the 2-oxo compound (II) and the dealkylated oxo compound (III), have been developed; the first measures I and II and the second measures III. The compounds are extracted from plasma with toluene and quantitated by electron-capture detection using the internal standard method. The methods are capable of quantitating plasma levels of I and II as low as 0.75 ng/mL and plasma levels of III as low as 1.5 ng/mL. Correlation coefficients of standard curves were greater than 0.9995 for all compounds. Precision of the methods was measured at two different concentrations for each compound; the CV values were 3-6% for all three compounds. The recovery of all compounds was greater than 80%, and the ratio of recovery of each compound to that of its internal standard did not vary at different concentrations, indicating appropriate internal standards have been selected for the methods. Quazepam metabolites, other benzodiazepines, and drugs which are potential comedication do not interfere with either method. The methods were shown to be suitable for investigating the bioavailability and pharmacokinetics of quazepam at therapeutic doses.