[Pharmacokinetics of digoxin in the aged]

Many elderly are treated with digitalis preparations. Both over- and under-dosage occur often. To obtain better dosage the pharmacokinetics of digoxin are discussed, as well as changes in it in the process of ageing. The body composition changes with ageing: the fat content increases and the lean body mass decreases. Moreover there is an important sex difference for all age categories. The decrease in lean body mass causes a decrease in distribution volume of digoxin. Furthermore it causes a decrease in creatinine production, masking the (physiological) decrease in glomerular filtration rate by 'normal' plasma creatinine levels. To estimate the renal function, determining digoxin elimination, with the plasma creatinine level, a formula is discussed with other parameters (weight, age, sex), that enables a reliable estimate. The renal function thus found enables estimation of the daily eliminated fraction. Combination of this estimate with a loading dose, reduced regarding the decreased distribution volume , results in a daily dose.