- for the treatment of congestive heart failure; also to slow the ventricular rate in dysrhythmias such as atrial fibrillation, atrial flutter and supraventricular tachycardia
- digoxin is a cardiac glycoside with positive inotropic and negative chronotropic actions
- the average oral absorption in neonates is approximately 70%
- peak serum levels after oral administration occur by 1 to 3 hours
- elimination half life in premature neonates is 61 to 170 hours and in full term neonates is 35 to 45 hours
- digoxin has a very large volume of distribution; the drug attains concentrations in tissues (eg. myocardium, skeletal muscle, kidney, liver) up to 150 times serum concentrations
- about 4 to 6 hours are required after an oral or IV dose for distribution to be complete; therefore, serum levels should not be taken before 6 to 8 hours, and preferably at least 12 hours, after administration of a dose
- serum digoxin is approximately 20% bound to plasma proteins in neonates
- an endogenous substance has been found in the serum of premature and term infants which cross-reacts with the radioimmunoassay (RIA)
- digoxin is eliminated mainly by the kidneys; its clearance from the body parallels the maturation of kidney function
- digoxin's positive ionotropic action is thought to be related to inhibition of the sarcolemmal Na+-K+ ATPase; the consequent elevation of intracellular Na+ activates the trans-sarcolemmal Na+-Ca exchange system; this creates an outflux of Na+, and an influx of Ca, resulting in a positive inotropic effect
- digoxin indirectly increases vagal activity, thus slowing SA and AV nodal activity
- toxic doses can produce cardiac arrhythmias, ventricular extrasystoles, AV block
- toxic effects are potentiated by high serum Ca, low serum K, and increased/decreased serum Mg
- vomiting, feeding intolerance, diarrhea
- drowsiness, lethargy
- therapeutic digoxin serum levels 1.0 - 2.6 nmol/L; these are somewhat unreliable in the newborn but are useful to indicate toxicity
- Routine Monitoring - digoxin serum levels should be taken after digitalization and once weekly while on maintenance therapy; serum levels are taken preferably at least 12 hours after administration of a dose
- monitor intake and output
- the response to digoxin is variable; a premature, asphyxiated or hypoxic baby is extremely sensitive
- take the apical heart rate for one full minute prior to giving the medication; if the heart rate is less than 100 beats/minute, consult the physician; the drug may be held and an ECG done to measure the PR interval to see if there is sinus arrhythmia
- in renal impairment, reduce or hold the dose of digoxin
TOTAL DIGITALIZING DOSE
The Total Loading (Digitalizing) Dose is administered in 3 Equally Divided Doses or in 3 Unequally Divided Doses (1/2, 1/4, 1/4) given every 8 hours.
|TOTAL DIGITALIZING DOSE|
|500 - 1000
1000 - 1500
1500 - 2000
15 to 22.5
22.5 to 30
20 to 30
30 to 40
THE DOSE MUST BE CHECKED AND SIGNED BY 2 STAFF (PHYSICIAN, REGISTERED NURSE, PHARMACIST) MEMBERS.
- IV dose can be given push
The first MAINTENANCE dose should NOT be given any earlier than 24 hours after the loading dose in premature infants any earlier than 12 hours after the loading dose in full-term neonates and infants (1-2 months old).
|DAILY MAINTENANCE DOSE|
|500 - 1000
1000 - 1500
1500 - 2000
4 to 5.5
5.5 to 7.5
5 to 7.5
7.5 to 10
- Pediatric Ampoule 50 mcg/mL (0.05 mg/mL), discontinued by manufacturer 2014
- Digoxin 0.25mcg/mL commercial product
- Pediatric Syringe 25 mcg/mL (0.025 mg/mL), prepared by Pharmacy
- Pediatric Elixir 50 mcg/mL (0.05 mg/mL)
- Roberts, RJ: Drug Therapy in Infants, W.B. Saunders, Toronto, 1984.
- Taketomo CK, Hodding JH and Kraus DM: Pediatric Dosage Handbook, Lexi-Comp Inc., Cleveland, 1992.
- Young TE and Mangum OB: Neofax - A Manual of Drugs Used in Neonatal Care, Columbus, Ohio: Ross Laboratories, 1992.
- Goldsmith JP, Karotkin EH and Barker S (eds): Assisted Ventilation of the Neonate, 2nd Edition, W.B. Saunders Co, 1988 (p.293).