Doxacurium pharmacodynamics in children during volatile and opioid-based anaesthesia

Area of Science:

• Anesthesiology
• Pharmacology

Background:

• The interaction between neuromuscular blocking agents like doxacurium and common anesthetic agents is crucial for pediatric surgical procedures.
• Limited data exists on the potentiation effects of halothane, isoflurane, and alfentanil on doxacurium in pediatric populations.

Purpose of the Study:

• To investigate and compare the dose-response effects of doxacurium when co-administered with halothane, isoflurane, or alfentanil in pediatric anesthesia.
• To determine the effective dose 50 (ED50) and effective dose 90 (ED90) of doxacurium under different anesthetic regimens in children.

Main Methods:

• A cumulative dose-response study utilizing electromyography was conducted in pediatric patients aged 2-10 years.
• Patients received anesthesia supplemented with either halothane (n=9), isoflurane (n=12), or alfentanil (n=9) alongside nitrous oxide/oxygen.
• Doxacurium doses were incrementally administered to achieve specific levels of neuromuscular blockade.

Main Results:

• Both isoflurane and halothane significantly potentiated the neuromuscular blocking effects of doxacurium compared to alfentanil.
• The ED50 of doxacurium was lower with halothane (23.9 µg/kg) than with alfentanil (32.7 µg/kg).
• The ED90 of doxacurium was lower with isoflurane (32.7 µg/kg) than with alfentanil (48.2 µg/kg), indicating increased potency (p < 0.05).

Conclusions:

• Inhalational anesthetics (halothane, isoflurane) increase doxacurium potency in pediatric patients compared to alfentanil.
• Anesthesiologists should consider these potentiating effects when calculating doxacurium doses for pediatric patients receiving these anesthetic agents.
• The duration of neuromuscular block was comparable across groups when equipotent doses were used, suggesting predictable recovery profiles once doses are adjusted for potency.