[Atracurium: neuromuscular blockade in repeated administration]

Area of Science:

• Anesthesiology
• Pharmacology
• Neuromuscular Blockade

Background:

• Neuromuscular blocking agents are crucial for surgical procedures.
• Atracurium and vecuronium are commonly used non-depolarizing muscle relaxants.
• Understanding their dose-response and duration is vital for anesthetic practice.

Purpose of the Study:

• To compare the neuromuscular blocking action of atracurium and vecuronium.
• To determine dose-response relationships and duration of action.
• To evaluate safety profiles, including cardiovascular effects and histamine release.

Main Methods:

• Study involved 74 surgical patients under balanced anesthesia.
• Atracurium (0.25 mg/kg initial, 0.1 mg/kg increments) and vecuronium (0.05 mg/kg initial, 0.0125 mg/kg increments) were administered.
• Neuromuscular function was monitored using EMG, with doses adjusted based on recovery to 30% of baseline.

Main Results:

• Atracurium is approximately 1/5 as potent as vecuronium (ED50: 0.13 mg/kg vs. 0.023 mg/kg).
• Both agents achieved ~90% blockade within 4 minutes; atracurium had a slightly longer 30% recovery time (26 min vs. vecuronium).
• Maintenance doses provided satisfactory relaxation; no cumulation observed. Recovery was 10-12 min for both, with no significant side effects.

Conclusions:

• Atracurium is a favorable neuromuscular blocker for anesthesia.
• It offers similar onset to vecuronium but a slightly longer, intermediate duration.
• The drug demonstrated a good safety profile within the studied dose range.