[Determination of plasma digoxin in newborn infants. Practical applications]

Measurement of plasma digoxin concentrations in infants after three increasing dosage levels shows that the optimal dose of this glycoside in 20 microgram/kg/day, i.e. a loading dose of 20 microgram/kg followed every 8 hours by a maintenance dose of 7 microgram/kg. The plateau concentration achieved is 3.0 +/- 0,5 ng/ml 8 hours after the last administration. When digoxin levels exceed 5 ng/ml (overdosage, renal failure or low body weight), toxic manifestations occur.