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.
Rodriguez
R J
RJ
Department of Pharmaceutical Sciences, College of Pharmacy, Oregon State University, Corvallis, OR 97331-3507, USA. Rosita.Rodriguez@orst.edu
Buckholz
C J
CJ
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