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Serum digoxin concentration and half-life in newborn
Insights
Newborns treated with digoxin showed serum levels influenced by higher doses per body weight, not reduced elimination. The average digoxin half-life in newborns was 30 hours, similar to adults without kidney disease.
Area of Science:
- Neonatal Pharmacology
- Pediatric Cardiology
Background:
- Digoxin is used to treat heart conditions in newborns.
- Understanding digoxin pharmacokinetics in neonates is crucial for safe and effective dosing.
Purpose of the Study:
- To determine serum digoxin concentration and half-life in mature newborns.
- To investigate factors influencing digoxin levels in neonates with respiratory distress or congenital heart disease.
Main Methods:
- Radioimmunological determination of serum digoxin levels and half-life in 9 newborns.
- Administered intravenous and oral digoxin loading doses, followed by maintenance doses.
- Monitored serum digoxin levels 12 hours post-dose and calculated half-life.
Main Results:
- Mean serum digoxin level at 12 hours was 2.0 ng/ml (range 1.4-2.5 ng/ml).
- Mean serum digoxin half-life was 30.0 hours (range 21.7-42.4 h).
- Newborn digoxin half-life was comparable to adults without renal disease.
Conclusions:
- Elevated serum digoxin levels in newborns are primarily due to higher administered doses per unit body weight.
- Digoxin elimination in mature newborns is not significantly diminished compared to adults.
- This suggests careful dose adjustment is key for neonatal digoxin therapy.
Abstract:
Serum digoxin concentration and half-life were radioimmunologically determined in 9 mature newborns after 7 days medication with digoxin. The newborns were in respiratory distress treated with continuous positive airway pressure or were suspected to have serious congenital heart disease. Loading dose was 26 mug/kg body weight intravenously and 35 mug/kg body weight orally, respectively. Maintenance dose corresponded to 1/8th of the digitalization dose twice daily. The serum digoxin level 12 h after the last dose varied between 1.4 and 2.5 ng/ml (mean 2.0 ng/ml, Sx=0.4). The serum half-life of digoxin varied between 21.7 and 42.4 h (mean 30.0 h, Sx=7.7). The mean serum half-life of digoxin of 30 h attained values found in adults without renal disease. This suggests that the serum digoxin levels of newborns which are usually higher if compared with those of adults result from higher digoxin doses per unit body weight and not from diminished digoxin elimination.