Interaction between quinidine and digoxin
E. B. Leahey Jr, J. A. Reiffel, R. E. Drusin, R. H. Heissenbuttel, W. P. Lovejoy and J. T. Bigger Jr
The serum digoxin concentration increased in 25 of 27 study patients (93%),
and the mean serum digoxin concentration rose from 1.4 ng/ml to 3.2 ng/ml
during quinidine therapy. Anorexia, nausea, or vomiting developed in 16
patients (59%) but disappeared in all ten patients for whom the digoxin
dose alone was reduced, suggesting that digoxin excess caused these
symptoms. Ventricular premature depolarizations developed in three patients
after starting quinidine therapy; ventricular tachycardia developed in one
patient, and another died suddenly. When starting quinidine therapy in
patients who are taking digoxin, the clinical course, ECG, and serum
digoxin level should be followed closely.
