title: The effect of three H2-receptor antagonists on the disposition of midazolam in the rat in-situ perfused liver model.
abstract: The rat in-situ perfused liver model was used to investigate the effect of three H2-receptor antagonists on the pharmacokinetic disposition of the short-acting benzodiazepine, midazolam. Perfusion experiments, using standard techniques, were carried out on four groups (one control and three H2-receptor antagonist-treated groups) of male Sprague-Dawley rats (300-350 g). All animals received midazolam 1 mg; the three treated groups received cimetidine (8 mg), ranitidine (3 mg) or famotidine (0.4 mg). Perfusate and bile samples were collected and assayed for midazolam using gas chromatography. The perfusate data indicated that midazolam disposition was impaired at 10, 50 and 60 min of the experimental period following the addition of cimetidine, whereas ranitidine and famotidine produced an effect at 10 min only; midazolam levels in bile were not affected by the presence of an H2-receptor antagonist. It was concluded that the limited inhibitory effect of cimetidine may be attributed to its lack of specificity for CYP3A, the isoenzyme responsible for the metabolism of midazolam.
authors.affiliation: School of Pharmacy, Queen's University of Belfast, UK.
authors.forename: C M
authors.initials: CM
authors.lastname: Hughes
authors.forename: J G
authors.initials: JG
authors.lastname: Swanton
authors.forename: P S
authors.initials: PS
authors.lastname: Collier
mesh_terms: D000818:Animals; D001646:Bile / Q000737:chemistry; D002849:Chromatography, Gas; D002927:Cimetidine / Q000008:administration & dosage / Q000494:pharmacology; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D004347:Drug Interactions; D015738:Famotidine / Q000008:administration & dosage / Q000494:pharmacology; D006635:Histamine H2 Antagonists / Q000008:administration & dosage / Q000494:pharmacology*; D008099:Liver / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D008297:Male; D008874:Midazolam / Q000378:metabolism / Q000493:pharmacokinetics*; D010477:Perfusion; D011899:Ranitidine / Q000008:administration & dosage / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D006635:Histamine H2 Antagonists; D015738:Famotidine; D002927:Cimetidine; D011899:Ranitidine; D003577:Cytochrome P-450 Enzyme System; D008874:Midazolam