DETERMINATION OF SERUM AND TISSUE-LEVELS OF PHENAZINES INCLUDING CLOFAZIMINE

A rapid and sensitive HPLC method is described for the analysis of syn thetic phenazines, including clofazimine, from a variety of biological samples. Phenazines were extracted from serum, tissue and fat using a mixture of dichloromethane and sodium hydroxide. The drugs were then quantified on a reversed-phase C-18 column using a mobile phase consis ting of 594 ml of water, 400 ml of tetrahydrofuran, 6 ml of concentrat ed acetic acid and 0.471 g of hexanesulfonic acid. In this mobile phas e, each phenazine tested had its own retention time. This allowed one phenazine to be used as an internal standard for the analysis of other phenazines. The method was validated for clofazimine ophenyl)-2,10-di hydro-2-(isopropylimino)phenazine] and B4090 2-(2,2,6,6-tetramethylpip erid-4-ylimino)phenazine] (VI) and shown to be accurate and precise ac ross a broad concentration range from 0.01 to 50 mu g/g (mu g/ml). Ext raction was 100% for each agent across this range. This system was use d to measure clofazimine and VI levels following their administration to rats. The pharmacokinetic profile of VI was different to that of cl ofazimine, with high tissue concentrations but lower fat levels.