Comparison of ketoconazole- and fluconazole-induced hepatotoxicity in a primary culture system of rat hepatocytes.

Ketoconazole (KT) and fluconazole (FLU) are azole antifungal agents with a broad spectrum of activity against both superficial and systemic mycoses. KT is also an anticancer agent in the treatment of advanced prostate cancer. In many clinical and retrospective studies, KT has been reported to cause liver damage, i.e. chemical hepatitis. Histologic analysis of KT induced hepatotoxicity shows massive centrilobular necrosis in which the hepatotoxicity was not thought to be mediated through an immunoallergic mechanism. According to the medical literature, the pattern of hepatic injury appears to be primarily of the hepatocellular type. Because of the documented reports of KT and FLU hepatotoxicity, a cytotoxicity comparison of KT and FLU was implemented. The objective of this comparison was to evaluate the cytotoxicity of these azoles such that future mechanistic investigations of hepatotoxicity could be performed. The relative hepatotoxicity of KT and FLU was evaluated using primary cultures of postnatal rat hepatocytes. Cytotoxicity was evaluated by measuring the leakage of the cytosolic enzyme, lactate dehydrogenase (LDH), into the medium; by assessing mitochondrial reduction of 3-(4,5-dimethythiazol-2yl)-2,5-diphenyl tetrazolium bromide (MTT); by assessing lysosomal uptake of neutral red (NR); and by gross morphology (phase contrast microscopy). The cultures were exposed to various concentrations of KT (56-188 microM) for 0.5-4 h and to various concentrations of FLU (50 microM to 1.0 mM) for 0.5-6 h. There was a significant increase (P < 0.05) in LDH leakage and a large decrease in MTT reduction and lysosomal uptake of NR at 4 h for KT. One millimolar FLU had minimal effects on the LDH leakage and MTT reduction. These results demonstrate that KT is a more potent cytotoxicant than FLU; and its toxicity was expressed in a dose- and time-dependent manner.