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The pharmacokinetics of droperidol in anesthetized children
Z Grunwald1, M Torjman, H Schieren
1Department of Anesthesiology, Jefferson Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania.
Insights
This study describes the pharmacokinetics of droperidol in children, finding lower clearance and volume of distribution compared to adults. These pediatric pharmacokinetic parameters do not fully explain droperidol's prolonged antiemetic effects.
Area of Science:
- Pharmacology
- Pediatric Anesthesiology
- Drug Metabolism
Background:
- Droperidol is widely used for pediatric nausea and vomiting.
- Pediatric pharmacokinetics of droperidol are not well-established.
- Understanding drug behavior in children is crucial for safe and effective treatment.
Purpose of the Study:
- To characterize the pharmacokinetics of intravenous droperidol in pediatric patients.
- To compare pediatric pharmacokinetic parameters with those reported in adults.
- To explore the relationship between droperidol pharmacokinetics and its clinical duration of action.
Main Methods:
- A pharmacokinetic study involving 12 pediatric patients undergoing tonsillectomy and adenoidectomy.
- Standardized anesthesia without premedication was administered.
- Droperidol (0.05 mg/kg) was given as an intravenous bolus, with plasma concentrations measured by radioimmunoassay.
Main Results:
- Key pharmacokinetic parameters in children (mean ± SD) included: elimination half-life (101.5 ± 26.4 min), mean residence time (127.2 ± 28.6 min), volume of distribution at steady state (0.58 ± 0.29 L/kg), and clearance (4.66 ± 2.28 mL·kg⁻¹·min⁻¹).
- Pediatric clearance and volume of distribution were lower than adult values, decreasing in parallel.
- Elimination half-life and mean residence time were similar to adult values.
Conclusions:
- The reduced volume of distribution in children is likely due to lower adipose tissue content.
- The pharmacokinetic profile, particularly the elimination half-life, does not fully account for the extended antiemetic effect of droperidol in pediatric patients.
- Clinical duration of drug action is influenced by factors beyond pharmacokinetics alone.
Abstract:
Despite the wide use of droperidol to reduce nausea and vomiting in children, its pharmacokinetics have not been described in pediatric patients. Twelve ASA Class I-II children, undergoing tonsillectomy and adenoidectomy, received standardized anesthesia; none of the children received premedication. After induction of general anesthesia, droperidol (0.05 mg/kg) was injected intravenously as a bolus. Droperidol plasma concentrations were determined by radioimmunoassay. Pharmacokinetic data were analyzed by model-independent methods. The pharmacokinetic parameters (mean +/- SD) for the studied population were elimination half-life: 101.5 +/- 26.4 min, mean residence time: 127.2 +/- 28.6 min, volume of distribution at steady state: 0.58 +/- 0.29 L/kg and clearance: 4.66 +/- 2.28 mL.kg-1 x min-1. The clearance and volume of distribution at steady state values are lower than those reported for the adult population, and they apparently decreased in a parallel fashion. The smaller volume of distribution at steady state is consistent with the lipophilic distribution of droperidol and the reduced content of adipose tissue in children. The elimination half-time and mean residence time values are similar to those reported previously for adults. The relatively short half-life of droperidol for our pediatric population does not explain its extended antiemetic action. It does, however, reaffirm that the pharmacokinetic duration of a drug's action is only one of the determinants of its clinical duration.