[The effects of oral carbocromen on the therapeutic and toxic effects of digitalis].

The arrhythmogenic and lethal doses of digoxin i.v. were determined in anaesthetized dogs, pretreated orally with placebo or with carbocromen 3-(2-diethylaminoethyl)-4-methyl-7-carbethoxy-methoxy)-2-oxo-1,2-chromene-hydrochloride (carbocromen, Intensain retard). Measurements of heart rate and dpldtmax during constant infusion of digoxin should demonstrate possible interference of carbocromen with the therapeutic effects of digoxin. Pretreatment of the animals (3--5 weeks) with carbocromen leads to strong protection against toxic effects of digoxin even 16--20 h after last dosing. Single oral application 1 h prior to anaesthesia also has a strong protective action. The behaviour of heart rate and dpldtmax in the treated animals is not different from that in the placebo group. The design of experiments and the results allow the conclusion that the different pharmacokinetics of carbocromen (serum) as compared to digoxin is of no consequence because the protective effects are not correlated to plasma levels.