Total Digitalizing Dose: 20 to 50 mcg/kg/DAY IV or PO.  The total digitalizing dose (TDD) is unequally divided (1/2 dose, 1/4 dose, 1/4 dose) and given every 8 hours. THE DOSE MUST ALWAYS BE CHECKED BY 2 PEOPLE BEFORE ADMINISTRATION!

Maintenance Dose: 2 to 5 mcg/kg/dose IV or PO Q 12 hours with the first maintenance dose given 24 hours after the last fraction of the TDD in premature infants and 12 hours after the last fraction of the TDD in term infants.   Potential adjustments to the maintenance dose.   THE DOSE MUST ALWAYS BE CHECKED BY 2 PEOPLE BEFORE ADMINISTRATION!

Comments: The two clinical indications for digoxin use in infants are decreased myocardial contractility (seen with congestive heart failure) and arrhythmias (supraventricular tachycardia), though the availability of newer drugs have replaced digoxin particularly in the latter situation. With impaired contractility (leading to CHF) the effectiveness of digoxin will depend upon the cause of the heart failure as well as the extent of myocardial damage. Digoxin may be useful in treating myocardial dysfunction following ischemia due to asphyxia neonatorum. It appears to have little value in treating myocardial dysfunction due to shock (septic, hypovolemic, or cardiogenic) that often accompanies asphyxia. The direct positive inotropic effect of digoxin increases cardiac output and decreases cardiac filling pressures. With circulatory improvement, sympathetic tone is decreased resulting in lower systemic vascular resistance (decreased afterload) and further improvement in cardiac output.

    Oral absorption is about 70% of a similar dose given IV. Although some reports have questioned the adequacy of absorption in the presence of congestive heart failure, others indicate that it is adequate for therapeutic purposes. Absorption of the oral dose is extremely rapid.

    The major disadvantage to its use is toxicity. Neonates appear to have some resistance to digoxin toxicity, though there have been deaths reported from its use in the newborn. Part of the difficulty in treating infants is the unreliability of serum levels. Serum concentrations of digoxin exceeding 3.5 ng/ml have been considered toxic. However, because of the presence of a digoxin-like immunoreactive substance (DLIS) in many infants, one must rely on clinical response and clinical signs of toxicity. THE DOSE MUST ALWAYS BE CHECKED BY 2 PEOPLE BEFORE ADMINISTRATION! For more information, see comments on digoxin.

Toxicity: Poor eating, vomiting, diarrhea, and arrhythmias are all signs of digitalis toxicity in the neonate (Driscoll. Clin Perinatol 1987; 14:931; Johnson. Pediatr 1982; 69:463). The diagnosis is often based on clinical findings due to the unreliability of serum levels. The cardiac disturbances are the potentially life-threatening and include PVC's, bigeminy, trigeminy, AV dissociation, AV block, bradycardia (extremely common side effect in the neonate), and CHF secondary to the above arrhythmias. Early recognition of the clinical evidence of toxicity is most important in treating the problem.  See treatment of digoxin toxicity.

Preparation:
IV: Digoxin (Lanoxin) is available in a 1 ml ampule (100 mcg/ml). Store at room temperature and protect from light. Use once and discard remaining medication. To prepare a 10 mcg/ml solution, draw up 1 ml of the 100 mcg/cc preparation into a 12 cc syringe. Draw 9 cc of SWFI, D5W, or normal saline into the syringe. Draw in sufficient air to allow for mixing.   If further dilution is necessary, the above dilution procedure is repeated using the 10 mcg/cc solution. Because of the small volumes used for VLBW infants and the time of infusion of the dose is 15 minutes, dilution to a final volume of 2 ml (using one of the above diluents) just prior to administration may be helpful.

PO: Digoxin (Lanoxin) is supplied as pediatric elixir 50 micrograms/ml (0.05 mg/ml) in 60 ml bottle. Store at room temperature; protect from light. May be further diluted with sterile water (see table below).

Compatibility: Compatible with TPN, lipids, and filter.  Compatible with D5W, normal saline, 0.45% sodium chloride, and sterile water for injection (PF).   Though also compatible with the following medications, it is best to infuse separately:  alprostadil, amrinone, famotidine, furosemide, heparin, hydrocortisone, lidocaine, meropenem, morphine, potassium chloride, and propofol.  It is incompatible with dobutamine, doxapram, and fluconazole. It is equivocally compatible with insulin..