In vitro anticoagulant-antacid interactions

Abstract

The adsorption characteristics of oral anticoagulants on some selected antacids were studied. The indanedione anticoagulants tested were: phenindione and diphenadione; while the coumarin anticoagulants tested were: dicoumarol, ethyl biscoumacetate, nicoumalone, phenprocoumon and warfarin.The antacids or adsorbents used were: aluminium glycinate, aluminium hydroxide, bismuth carbonate, bismuth salicylates bismuth subgallate, bismuth subnitrate, calcium carbonate, charcoal, dihydroxyaluminium sodium carbonate, magaldrate, magnesium carbonate, magnesium oxide, magnesium trisilicate and kaolin.Adsorption of phenindione was significant on charcoal and magnesium oxide. Aluminium hydroxide, bismuth carbonate, subnitrate and salicylate adsorbed phenindione to a lesser extent. Other substances showed relative weak adsorption properties. Diphenadione, on the other hand, was adsorbed on most substances tested.The extent of dicoumarol adsorbed was quite high on bismuth carbonate, salicylate and subnitrate as well as on magnesium oxide. It was intermediate on aluminium glycinate and magaldrate. The amount of the anticoagulant adsorbed on aluminium hydroxide, bismuth subgallate and magnesium trisilicate, under the experimental conditions, was quite low. Glycine was found to reduce the amount of dicoumarol adsorbed on bismuth carbonate and to a lower extent on magnesium oxide, while it had a negligible effect on the amount adsorbed on bismuth subnitrate. The other coumarin derivatives showed no or very low adsorption tendencies for the substances tested, with the exception of charcoal, bismuth subnitrate and salicylate.Adsorption isotherms were plotted for phenindione and dicoumarol.The dissolution of phenindione decreased in the presence of the adsorbing substance especially in acidic medium. The dissolution of dicoumarol in the presence of magnesium oxide was also decreased.