Artery-to-muscle onset time for neuromuscular blocking drugs

Area of Science:

• Anesthesiology
• Pharmacology
• Neuromuscular Pharmacology

Background:

• Neuromuscular blocking agents are crucial in anesthesia.
• Understanding their onset times is vital for clinical practice.
• Artery-to-muscle (A-M) onset time provides a direct measure of drug delivery to target receptors.

Purpose of the Study:

• To determine and compare the A-M onset times of five neuromuscular blocking agents.
• To evaluate the relationship between latent and manifest A-M onset times.
• To correlate A-M onset times with previously reported intravenous onset times.

Main Methods:

• Fifty female patients under light endotracheal anesthesia were studied.
• Circulation to one arm was occluded for 1 minute after intravenous drug injection into the contralateral arm.
• Muscle twitch response in the occluded limb was measured after nerve stimulation to determine latent and manifest onset times.

Main Results:

• Mean latent A-M onset times varied significantly among the five drugs (P < 0.005).
• Suxamethonium (4.8 s) and fazadinium (8.6 s) had the fastest latent onset times.
• Pancuronium (31.9 s), tubocurarine (21 s), and alcuronium (17.2 s) exhibited significantly longer latent onset times.
• Manifest A-M onset times generally correlated with latent onset times, with tubocurarine being an exception due to a slower decline in twitch height.

Conclusions:

• Significant differences exist in the A-M onset times of commonly used neuromuscular blocking agents.
• Latent A-M onset time is a reliable indicator and correlates well with clinical intravenous onset times.
• These findings aid in selecting appropriate neuromuscular blocking agents based on desired onset speed in clinical anesthesia.