Simple method to predict digoxin serum concentration.

The predictability of a method of determining serum digoxin concentration was assessed in a retrospective study of 35 hospitalized patients taking digoxin orally for maintenance therapy. Simple pharmacokinetic expressions were used to estimate digoxin concentration. Clinically, the mean measured digoxin concentration (1.35 ng/ml) was in close agreement with the mean predicted value (1.36 ng/ml). There was also a strong statistical correlation between measured and predicted values (r = .82). The predictability of serum digoxin concentration was statistically equivalent in men and women. Our results indicate that a reasonably accurate prediction of digoxin concentration is possible using simple mathematical formulas that require only routine clinical data.