Plasma digoxin levels in infants, children and adults, using a radioimmunoassay micromethod.

The radioimmunoassay method for estimation of plasma digoxin concentration was modified to use samples of 0.1 ml plasma for use in infants and children. The optimal daily maintenance dose for neonates, infants, and children was found to be between 0.01 and 0.015 mg/kg. Despite high plasma digoxin concentration (3-4 ng/ml) in some infants and children, no evidence of toxicity was found on electrocardiogram. 3 patients with accidental overdose, however, had plasma digoxin levels above 5 ng/ml and 2 of these had atrioventricular block.