Determination of ketoconazole in the plasma, liver, lung and adrenal of the rat by high-performance liquid chromatography.

An accurate and precise procedure for the rapid analysis of ketoconazole in the lung, liver, plasma and adrenal gland of the rat has been developed. Separation of the drug from endogenous substances was achieved by solid-phase extraction followed by reversed-phase chromatography on a Novapak C18 column using a mobile phase of methanol--acetonitrile--0.02 M phosphate buffer (pH 6.8) (35:30:35). Depending on the tissue, the recoveries of ketoconazole and clotrimazole, which was used as an internal standard, ranged between 85.0 to 93.6% and 79.3 to 84.1%, respectively. The reproducibility of the assay was between 3 and 4%, depending on the tissue involved. The sensitivity of the procedure permitted the monitoring of ketoconazole levels for up to 24 h in the adrenal and up to 48 h for plasma, lung and liver, following oral administration of 150 mg/kg of the drug to male rats.