title: Assessment of cytochrome P4502E1 induction in alcoholic patients by chlorzoxazone pharmacokinetics.
abstract: Chlorzoxazone is mainly metabolized to 6-hydroxychloroxazone (6-OHchlorzoxazone) by the ethanol-inducible cytochrome P450 2E1 (CYP2E1). To evaluate the impact of ethanol consumption on the enzyme induction, the pharmacokinetics of chlorozoxazone and 6-OHchlorzoxazone were studied in alcoholic and control subjects. Fifteen alcoholic male inpatients (all smokers, daily intake 333 +/- 191 g of absolute ethanol) and 20 healthy male volunteers (10 smokers and 10 non-smokers, weekly intake < 100 g of absolute ethanol) participated in this study. Following a 12 hr fasting period, each subject was orally administered 500 mg of chlorzoxazone. Venous blood and urine samples were collected over a 10 hr period. Areas under the curve of plasma concentration versus time (AUC) of chlorzoxazone and 6-OHchlorzoxazone was calculated. The total plasma clearance of chlorzoxazone was measured as the dose/AUC ratio. The mean total plasma clearance was not different between smoker and non-smoker controls but it was enhanced by 73% in alcoholic patients. These results indicate a negligible and non-significant effect of cigarette smoking in controls but an increased metabolism of chlorzoxazone in alcoholic patients (P < 0.05). This increase was corroborated by the 2-fold enhancement of the 6-OHchlorzoxazone/chlorzoxazone AUC ratio, compared to controls. A good correlation was found between this AUC ratio and the 6-OHchlorzoxazone/chlorzoxazone concentration ratio at t = 2 hr in patients and in controls (r = 0.88 and 0.85, respectively, P < 0.01). The concentration ratio increased by 150% in alcoholic patients and decreased by 65% in the seven alcoholics tested after 7 days of alcohol abstinence. It is therefore concluded that the 6-OHchlorzoxazone/chlorzoxazone concentration ratio at t = 2 hr could constitute a simple and non-traumatic marker of CYP2E1 induction.
authors.affiliation: Clinique Toxicologique, Hopital Fernand Widal, Paris, France.
authors.forename: C
authors.initials: C
authors.lastname: Girre
authors.forename: D
authors.initials: D
authors.lastname: Lucas
authors.forename: E
authors.initials: E
authors.lastname: Hispard
authors.forename: C
authors.initials: C
authors.lastname: Menez
authors.forename: S
authors.initials: S
authors.lastname: Dally
authors.forename: J F
authors.initials: JF
authors.lastname: Menez
mesh_terms: D000328:Adult; D000410:Alanine Transaminase / Q000097:blood; D000437:Alcoholism / Q000097:blood / Q000201:enzymology*; D001219:Aspartate Aminotransferases / Q000097:blood; D002753:Chlorzoxazone / Q000031:analogs & derivatives / Q000493:pharmacokinetics*; D003577:Cytochrome P-450 Enzyme System / Q000096:biosynthesis*; D004790:Enzyme Induction / Q000187:drug effects; D006801:Humans; D008297:Male; D008657:Metabolic Clearance Rate; D008875:Middle Aged; D005723:gamma-Glutamyltransferase / Q000097:blood
chemical_list: C039289:6-hydroxychlorzoxazone; D003577:Cytochrome P-450 Enzyme System; D005723:gamma-Glutamyltransferase; D001219:Aspartate Aminotransferases; D000410:Alanine Transaminase; D002753:Chlorzoxazone