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Multiple-dose kinetics of digoxin in neonates
Insights
Digoxin pharmacokinetics in neonates showed stable parameters over seven days of therapy. This suggests consistent drug processing in this vulnerable population, aiding safe dosing strategies.
Area of Science:
- Neonatal Pharmacology
- Clinical Pharmacokinetics
- Pediatric Drug Metabolism
Background:
- Digoxin is commonly prescribed for neonatal heart conditions.
- Understanding digoxin's pharmacokinetic profile in neonates is crucial for safe and effective treatment.
- Limited data exists on the changes in digoxin kinetics during the first week of intravenous therapy in neonates.
Purpose of the Study:
- To investigate the multiple-dose pharmacokinetics of digoxin in neonates over a 7-day period.
- To determine if key kinetic parameters change significantly during the initial week of intravenous digoxin therapy.
- To assess the stability of digoxin's absorption, distribution, metabolism, and excretion in this population.
Main Methods:
- Five neonates receiving intravenous digoxin therapy were studied.
- Serum digoxin levels and urinary excretion were measured after the 1st and 7th doses.
- Creatinine clearance, renal digoxin clearance, total body digoxin clearance, volume of distribution, and half-life were calculated.
Main Results:
- Creatinine clearance averaged 12-13 ml/min/1.73 m2.
- Renal and total body digoxin clearance showed no significant changes from day 1 to day 7.
- Volume of distribution and half-life remained stable, with values of approximately 7 L/kg and 48 hours, respectively.
Conclusions:
- Neonatal digoxin pharmacokinetics, including clearance and half-life, are stable during the first week of intravenous therapy.
- These findings support consistent dosing regimens for digoxin in neonates.
- Further research may explore longer-term kinetics and effects of varying gestational and postnatal ages.
Abstract:
Multiple-dose kinetics of digoxin were studied over a 7-day period in five neonates receiving intravenous digoxin therapy (one initial digitalizing dose followed by single daily doses). Their weights ranged from 1.04 to 2.68 kg (means = 1.61 kg), gestational ages from 28 to 39 weeks (means = 31.8 weeks), and postnatal ages from 2 to 19 days (means = 8.0 days). The 24-hour serum digoxin levels and urinary creatinine and digoxin excretion after the 1st and 7th doses on days 1 and 7 were employed to derive the kinetic parameters. Values of each following parameter (mean +/- SD) were obtained on days 1 and 7, respectively: (1) creatinine clearance (ml/min/1.73 m2) 12 +/- 6, 13 +/- 8; (2) renal digoxin clearance (ml/min/1.73 m2) 13 +/- 8, 15 +/- 10; (3) total body digoxin clearance (ml/min/1.73 m2) 35 +/- 14, 39 +/- 24; (4) volume of distribution (L/kg) 7.2 +/- 1.0, 6.9 +/- 1.1; and (5) half-life (hours) 48 +/- 19, 49 +/- 27. No consistent changes of the above kinetic parameters from days 1 to 7 were observed in these five neonates (P greater than 0.05, paired student's t-test).