A pharmacokinetic study of digoxin holiday dosing practice in Egypt: A prospective-randomized trial

Abstract

BackgroundBecause of the narrow therapeutic index of digoxin, most cardiologists in Egypt give digoxin holiday for atrial fibrillation and heart failure, it is not clear if the interrupted digoxin regimens are effective since serum digoxin concentrations might fall below the therapeutic range. ObjectiveTo evaluate and compare the digoxin serum concentration and patient’s quality of life in the continuous versus interrupted digoxin dosing regimens. MethodsPatients were randomized to receive one of four regimens: regimen 1: 0.25mg daily except Friday (N=17); regimen 2: 0.25mg daily except Thursday and Friday (N=17); regimen 3: 0.125mg daily (N=17); and regimen 4: a tailored dose was calculated based on renal function and given daily (N=23). After reaching steady state in the two holiday regimens, two plasma samples were collected (preholiday and post holiday trough concentrations); in the other two groups one trough plasma sample was collected. Quality of life questionnaire for atrial fibrillation (QLAF), was administered to all patients at baseline and then after at least one month of digoxin therapy. ResultsThere was a statistically significant difference between the preholiday trough concentration and the trough steady state concentration across the four regimens (p=0.002). There was no significant difference in the QLAF questionnaire domains, total scores at baseline, or after the follow up between the four regimens. ConclusionOnce daily tablet (0.25mg) was suitable in maintaining digoxin serum concentration in the recommended therapeutic range, fluctuation in digoxin serum concentration did not affect quality of life for atrial fibrillation patients.