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Pharmacokinetics of dopamine in critically ill newborn infants
J F Padbury1, Y Agata, B G Baylen
1Department of Pediatrics, Harbor-UCLA Medical Center, University of California, Los Angeles School of Medicine, Torrance 90509.
Insights
This study shows that dopamine pharmacokinetics in critically ill neonates follows first-order kinetics. Dopamine clearance rates remained stable across varying concentrations during infusions.
Area of Science:
- Neonatal pharmacology
- Clinical pharmacokinetics
- Critical care medicine
Background:
- Dopamine is frequently used in critically ill neonates to manage hemodynamic instability.
- Understanding dopamine pharmacokinetics is crucial for optimizing its therapeutic use in this vulnerable population.
- Limited data exist on dopamine pharmacokinetics in neonates, particularly those with critical illnesses.
Purpose of the Study:
- To characterize the pharmacokinetics of dopamine in critically ill newborn infants.
- To determine the relationship between dopamine infusion rates and plasma concentrations.
- To assess the impact of dopamine concentration and infusion rate on plasma clearance.
Main Methods:
- Investigated 14 critically ill neonates (27-43 weeks gestational age, 0.9-4+ kg birth weight).
- Dopamine was administered via controlled, stepwise increasing infusions up to 8 micrograms/kg/min.
- Plasma dopamine concentrations and clearance rates were measured from duplicate samples during infusions.
Main Results:
- Steady-state dopamine levels and clearance were achieved within 20 minutes.
- Plasma dopamine concentrations ranged from 0.5 ng/ml to nearly 70 ng/ml at higher infusion rates.
- A significant linear correlation (r=0.68, p<0.001) was found between dopamine infusion rate and plasma concentration.
- Clearance rate was not significantly affected by dopamine concentration or infusion rate.
Conclusions:
- Dopamine exhibits first-order kinetics in critically ill neonates within the studied concentration range.
- These findings support predictable dopamine dosing strategies in neonatal critical care.
- Further research may refine dosing guidelines for dopamine in specific neonatal subpopulations.
Abstract:
Dopamine pharmacokinetics was investigated in 14 critically ill newborn infants ranging from 27 to 43 weeks of gestational age and from 0.9 to greater than 4 kg birth weight. Plasma clearance rate was determined from dopamine levels during controlled infusions under actual clinical conditions. Dopamine was administered in stepwise increasing doses up to 8 micrograms/kg/min. Dopamine concentration and dopamine clearance rate were determined from duplicate samples drawn during each infusion in each patient. Steady-state plasma dopamine concentrations and plasma clearance rates were observed within 20 minutes at each infusion. Plasma dopamine concentration ranged from 0.5 ng/ml before infusion to almost 70 ng/ml at an infusion rate of 4 to 8 micrograms/kg/min. There was a linear correlation between infusion rate and plasma dopamine concentration (r = 0.68, p less than 0.001). Neither plasma dopamine concentration nor infusion rate had a significant effect on clearance rate. These data are consistent with first-order kinetics for administered dopamine in critically ill neonates over the range of concentrations studied.