title: Decreased bioavailability of digoxin due to antacids and kaolin-pectin.
abstract: Employing a Latin-square design and single-dose studies of bioavailability in 10 normal human volunteers, we tested the hypothesis that antacids and kaolin-pectin might interfere with the bioavailability of orally administered digoxin. Cumulative six-day urinary digoxin excretion (expressed as the percentage of a 0.75-mg dose recovered) was: control, 40.1+/-3.0 (S.E.); aluminum hydroxide, 30.7+/-2.9; magnesium hydroxide, 27.1+/-2.4; magnesium trisilicate, 29.1+/-1.7; and kaolin-pectin 23.4+/-2.0. The differences in means were highly significant (F = 10.47, P less than 0.005). Further analysis (multiple comparison test) revealed that control differed significantly from each of the other treatments (alpha = 0.05), but there was no such difference between any of the other treatment groups. The decreased cumulative excretion produced by antacids and kaolin-pectin reflected a striking reduction in digoxin absorption associated with these compounds that was not related to alteration of gut transit time or to adsorption of digoxin to these gastrointestinal medications.
mesh_terms: D000284:Administration, Oral; D000863:Antacids / Q000494:pharmacology*; D001682:Biological Availability; D004077:Digoxin / Q000008:administration & dosage / Q000378:metabolism* / Q000652:urine; D004347:Drug Interactions; D006207:Half-Life; D006801:Humans; D007408:Intestinal Absorption / Q000187:drug effects; D007421:Intestine, Small / Q000378:metabolism; D007616:Kaolin / Q000494:pharmacology*; D010368:Pectins / Q000494:pharmacology*
chemical_list: D000863:Antacids; D007616:Kaolin; D004077:Digoxin; D010368:Pectins