노인환자에서 Digoxin의 약동학적 매개변수 변화

A Variation of Pharamcokinetic Parameters of Digoxin in Elderly Patients

The elderly patients are the most frequent users of digoxin because of increased prevalence of the two primary indications for digoxin therapy; atrial fibrillation (AF) and congestive heart failure (CHF). This study was Performed to observe a variation in digoxin pharmacokinetic parameters in advancing age and changing kidney function, and to compare the measured clearance with the calculated clearance. The 123 drug monitoring records of inpatients who had achieved steady state concentration of digoxin at a tertiary hospital from April 1999 to October 2001 were reviewed. In advancing age, measured digoxin clearance, volume of distribution and creatinine clearance were reduced. Compared with the calculated digoxin clearance, the measured digoxin clearance was more reduced in patients without CHF Especial1y: in elderly patents without CHF the measured digoxin clearance was lower than the calculated digoxin clearance. In contrast to non-CHF patients the measured value was greater than the calculated value in all CHF patients. Findings from this study indicate that the calculated digoxin clearance in elderly patients without CHF substantially overestimated the true clearance. Thus, it appears that the use of calculated digoxin clearance to estimate serum digoxin concentration may result in underestimation of the true serum concentration in a number of elderly patients without CHF.