title: Ca2+ channel antagonists inhibit the intestinal absorption of digoxin in the guinea-pig.
abstract: Simultaneous administration of digoxin and Ca2+ channel antagonists results in an increased plasma level of digoxin. A possible mechanism underlying this interaction might be the influence of Ca2+ channel antagonists on the enteral absorption of digoxin. To study this interaction, two groups of experiments were performed with guinea-pigs. In the first group, the influence of Ca2+ channel antagonists on the rate of enteral absorption of digoxin in vivo was studied. In the second group, the influence of Ca2+ channel antagonists on the transfer of digoxin through the wall of the isolated everted small intestine in vitro was investigated. The intravenously determined minimal lethal dose of digoxin 30 min after its intraduodenal administration was increased in animals pretreated with either verapamil, diltiazem, nifedipine or nicardipine. Addition of either verapamil or diltiazem to the solution on the mucosal side of isolated everted small intestine sacs decreased the transfer of digoxin through the intestinal wall. Similar results obtained in both groups indicate that, under our experimental conditions, Ca2+ channel antagonists inhibit the enteral absorption of digoxin in the guinea-pig.
authors.affiliation: Department of Pharmacology and Experimental Toxicology, Medical Faculty, University of Ljublijana, Slovenia.
authors.forename: M V
authors.initials: MV
authors.lastname: Budihna
authors.forename: P
authors.initials: P
authors.lastname: Strojan
mesh_terms: D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D004077:Digoxin / Q000493:pharmacokinetics*; D004347:Drug Interactions; D005260:Female; D006168:Guinea Pigs; D066298:In Vitro Techniques; D007408:Intestinal Absorption / Q000187:drug effects*; D008297:Male
chemical_list: D002121:Calcium Channel Blockers; D004077:Digoxin