Serum Digoxin Concentration and Age*

A review was conducted of the charts of 79 consecutive inpatients (age range, 17-93 years) who were in a steady state with respect to digoxin dosage, and had serum creatinine levels below 1.6 mg/dl or urea nitrogen levels below 26 mg/dl. In these patients whose renal function was not impaired, there was no correlation between age and the serum digoxin level normalized for dosage. Concurrent administration of quinidine significantly elevated digoxin concentration. Patients with congestive heart failure showed a higher serum digoxin level than did those without heart failure. Thus, age appeared to have little, if any effect on the relationship between the dose of digoxin and the steady-state serum level when the factor of impaired renal function (often associated with aging) was eliminated.