Evaluation of the relationship between steady state serum digoxin concentration and toxicity

ABSTRACT

This study was conducted to determine the serum digoxin concentration [SDC] at which there is an increase in the signs and symptoms of digoxin toxicity. Demographic characteristics, disease[s], clinical and para-clinical signs and symptoms of 79 patients who were using digoxin for at least one month were recorded. Prolonged PR, bradycardia, shortened QT, PVC [especially with bigeminy], sinus arrest, junctional extrasystole and symptoms like nausea/vomiting, diarrhoea, anorexia, fatigue, headache and visual disturbances were defined as symptoms of toxicity. From 1.2 ng/ml an increase in electrophysiological signs of toxicity was observed and it rose steeply at SDCs above 1.6 ng/ml. No relationship was found between SDC and symptoms of toxicity. Signs of digoxin toxicity appear even at levels below 2.0 ng/ml. Thus, target SDC should not exceed 1.6 ng/ml