Verapamil-Digoxin Interaction

To the Editor: Dr. Doering wrote in the August 23, 1979, issue that no drug except quinidine influenced the serum levels of digoxin. In Table 1 in his article, specific reference was made to verapamil. Since our experience seems to be different, we think it is important to bring our results to the attention of your readers. In the past five years, we have been treating chronic atrial fibrillation with verapamil to decrease atrioventricular conduction and slow the ventricular rate.* In the course of treating 41 patients, we found that serum digoxin levels increased from 0.96±0.08 to 1.63±0.12 ng per.