Cardiovascular Effects of Digoxin—Phenelzine Interaction in Rabbits

The potential toxicity of combining phenelzine, an MAO inhibitor, and digoxin, a cardiac glycoside, was studied in rabbits. Cardiovascular responses following concurrent administration of these drugs and the administration of these drugs 20 and 60min. apart, respectively, revealed that phenelzine and digoxin evoked arrhythmias in about 50% of all rabbits tested without markedly altering the arterial blood pressure. Spontaneous heart rate in these animals was found to be lower than control values. The incidence of arrhythmia decreased as the time interval between the administration of both drugs was increased from 20 to 60min. An increase in the number of days of pretreatment with phenelzine resulted in the use of a higher dose of digoxin to evoke arrhythmia.