title: Inhibitory effect of 4-methylpyrazole on antipyrine clearance in rats.
abstract: Pyrazole and 4-methylpyrazole (4-MP) are potent, effective inhibitors of alcohol dehydrogenase. Pyrazole and its derivatives also have been shown to affect the cytochrome P-450 dependent monooxygenase system. This study was performed to investigate the effect of 4-MP on the disposition kinetics of antipyrine (AP). Groups of male Fisher 344 rats were given an ip injection of 4-MP (100 mg/kg) or 4-MP HCl (equivalent to 4-MP 100 mg/kg) or an equivalent volume of saline. AP (20 mg/kg) was injected intravenously via the jugular vein catheter 30 minutes later. Blood samples were collected upto 24 hours and assayed by HPLC. 4-MP pretreatment significantly decreased AP clearance from 0.490 +/- 0.032 to 0.095 +/- 0.014 (4-MP HCl) and 0.076 +/- 0.008 (4-MP) L/hr.kg (p less than 0.01). The volume of distribution of AP decreased from 0.82 +/- 0.07 to 0.65 +/- 0.06 (4-MP HCl) and 0.56 +/- 0.04 (4-MP) L/kg (p less than 0.05). Mean residence time increased from 1.68 +/- 0.09 to 6.91 +/- 0.58 (4-MP HCl) and 7.39 +/- 0.56 (4-MP) hr (p less than 0.01). These results demonstrate a significant inhibitory effect of 4-MP on the cytochrome P-450 isozyme(s) which is responsible for AP metabolism in intact animals.
authors.affiliation: Department of Pharmaceutical Sciences, College of Pharmacy, University of Arizona, Tucson 85721.
authors.forename: H H
authors.initials: HH
authors.lastname: Chow
authors.forename: A
authors.initials: A
authors.lastname: Hutchaleelaha
authors.forename: M
authors.initials: M
authors.lastname: Mayersohn
mesh_terms: D000818:Animals; D000983:Antipyrine / Q000378:metabolism* / Q000493:pharmacokinetics; D002851:Chromatography, High Pressure Liquid; D003577:Cytochrome P-450 Enzyme System / Q000187:drug effects*; D000077604:Fomepizole; D008297:Male; D011720:Pyrazoles / Q000494:pharmacology*; D051381:Rats; D011916:Rats, Inbred F344; D013997:Time Factors
chemical_list: D011720:Pyrazoles; D000077604:Fomepizole; D003577:Cytochrome P-450 Enzyme System; D000983:Antipyrine