[Determination of unchanged clobazam in plasma by gas-liquid chromatography]

A method has been developed for gas-chromatographic determination of clobazam in human plasma using a nitrogen-selective detector. The unchanged drug was extracted from the plasma at pH 9 by benzene. The method used methyl-1-clonazepam as internal standard. Calibration graphs were linear in the range of 20 to 10,000 ng/ml. The recovery of the compound was 102.29%. The sensitivity of the method was adequate for determination of the drug at toxic concentrations and at therapeutic doses. It was a simple, rapid, reproductible method for determination of clobazam and most of the commercialized benzodiazepines. The method has been tested in a few number of clinicals cases. No interferences occurred in plasma from patients treated with various drugs.