Serum digoxin levels in neonates whose weights are less than 1,500 grams.

Digoxin was given to 29 infants in congestive heart failure and weighing less than 1,500 gm. All the infants were considered to have an isolated patent ductus arteriosus and were recovering from the respiratory distress syndrome. Forty-eight serum digoxin levels were measured after 4 or more days on twice daily parenteral maintenance therapy and a significant correlation obtained between the dose and resultant serum level (P less than .001). A total parenteral maintenance dose of 5 micrograms/kg produced a serum level of 2.4 ng/ml (+/- 1.2 ng). This is a much lower dose regime than in frequently recommended and underscores the need for caution in digitalizing small premature infants.