Tolerance to Hydralazine in Congestive Heart Failure

To the Editor: The article by Packer et al.¹ in the January 14 issue provided valuable information on the development of tolerance to long-term hydralazine therapy in some patients with congestive heart failure. I believe, however, that the potential role of fluctuations in the effects of digoxin was not adequately considered. Packer et al. did not indicate the serum digoxin concentrations of their patients, nor did they indicate that any digoxin dosage adjustments were made after the initiation of vasodilating agents. Although the authors acknowledged that hemodynamic alterations may produce changes in the absorption of orally administered drugs (including digoxin),.