[Best result of digoxin dosing in the aged by taking into account that both the elimination as well as the volume of distribution of the drug decrease when the kidney function deteriorates].
PURPOSE: To evaluate three methods for digoxin dose adjustment in aged patients. METHODS: We determined the plasma digoxin levels that would be attained in 87 old patients with doses adjusted to the kidney function by means of three separate procedures. RESULTS: Age: 79.0 "6.3 years of age; creatinin clearance (Clc): 0.70" 0.23 ml/Kg of lean body weight and minute. Only the methods that adjust both the digoxin clearance and the volume of distribution to the Clc achieve the independence between the digoxinemia and the kidney function. The best of them, by calculating the elimination constant (K) and the volume of distribution (V) as linear functions of the Clc, so that K ranges between 0.173 and 0.462 days-1 and V between 4 and 10 l/Kg of lean body weight when the Clc varies from 0 to 110 ml/minute, achieve digoxinemia figures between 0.8 y 2.0 ng/ml and above 2.0 ng/ml in the 81.6% and 0.0% of the patients (95% confidence intervals (95% CI): 72.2% to 88.4 and 0.0% to 4.6%), respectively; with a precision and a bias of 0.43 and -0.06 ng/ml (95% CI: 0.38 to 0.48 and -0.16 to 0.03 ng/ml), respectively. CONCLUSION: The described method would lead to good results if digoxin has not been prescribed in order to control the cardiac frequency in the setting of auricular fibrilation.