[Digitoxin plasma concentrations during oral treatment (author's transl)]

In 198 patients, among them 153 with a creatinine clearance of less than 20 ml/min, the relationship between the digitoxin plasma level and retrospective data on daily digitoxin dose, age, body weight and renal function has been evaluated. A multiple regression analysis yielded only a very weak correlation (100 r2 = 13.2%, n = 186), with the digitoxin dose having by far the highest partial coefficient of determination (100 r2 = 11.5%). The partial correlation for the renal function was too small as to be relevant (100 r2 = 0.6%). Owing to the weakness of correlation it is impossible to predict the digitoxin plasma level on the basis of standard clinical data. A single dose in the range of 0.07 to 0.1 mg/day seems to be an appropriate treatment for most patients. Corresponding to a median dose of 0.082 mg digitoxin daily during steady state a median plasma level of 14.6 ng/ml has been calculated.