Hepatotoxicity of ketoconazole in Sprague-Dawley rats: glutathione depletion, flavin-containing monooxygenases-mediated bioactivation and hepatic covalent binding.
1. This study has examined ketoconazole (KT)-induced hepatotoxicity in vivo and in vitro, using male Sprague-Dawley rats with [(3)H]KT (1.5 micro Ci mg(-1)) at 40 and 90 mg KT kg(-1) doses. Blood and liver samples were collected from 0 to 24 h for alanine aminotransaminase (ALT), glutathione (GSH) and covalent binding analyses. 2. Covalent binding occurred as early as 0.5 h, peaked at 2 h (0.026 +/- 0.01 nmol KT mg(-1) protein) and 8 h (0.088 +/- 0.04 nmol KT mg(-1) protein) for 40 and 90 mg KT kg(-1) doses, respectively. ALT levels increased at 0.5 h for the 40 and 90 mg KT kg(-1) doses (44.3 and 56.4 U ml(-1), respectively) relative to control, 22.7 U ml(-1). At 24 h, the 90 mg KT kg(-1) dose reduced hepatic GSH levels from 9.92 +/- 1.1 to 4.76 +/- 0.3 nmol GSH mg(-1) protein. 3. The role of the flavin-containing monooxygenases (FMO) utilized Sprague-Dawley microsomes with 1, 10 and 100 micro M [(3)H]KT. Maximum covalent binding occurring at 100 micro M KT. Heat inactivation of microsomal FMO significantly decreased covalent binding by 75%, whereas 1 mM GSH significantly reduced covalent binding by 65%. 4. Thus, KT-induced hepatotoxicity is dose- and time-dependent and appears to be FMO mediated, in part, to metabolites that may react with protein and, possibly, GSH.
Department of Pharmaceutical Sciences, College of Pharmacy, Oregon State University, Corvallis, OR 97331-3507, USA. Rosita.Rodriguez@orst.edu
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Buckholz
D000410:Alanine Transaminase / Q000378:metabolism; D000818:Animals; D000935:Antifungal Agents / Q000493:pharmacokinetics / Q000633:toxicity*; D001711:Biotransformation / Q000187:drug effects; D056486:Chemical and Drug Induced Liver Injury / Q000201:enzymology / Q000378:metabolism*; D005978:Glutathione / Q000378:metabolism*; D007274:Injections, Intraperitoneal; D007654:Ketoconazole / Q000493:pharmacokinetics / Q000633:toxicity*; D008099:Liver / Q000201:enzymology / Q000378:metabolism*; D008297:Male; D008862:Microsomes, Liver / Q000187:drug effects / Q000201:enzymology; D008995:Monoamine Oxidase / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley
D000935:Antifungal Agents; D008995:Monoamine Oxidase; D000410:Alanine Transaminase; D005978:Glutathione; D007654:Ketoconazole