Buccal absorption of etomidate from a solid formulation in dogs

Area of Science:

• Pharmacology
• Drug Delivery Systems
• Anesthesiology

Background:

• Etomidate is commonly administered intravenously for general anesthesia induction.
• Oral transmucosal absorption could expand etomidate's utility to premedication and conscious sedation.

Purpose of the Study:

• To investigate the oral mucosal absorption kinetics and bioavailability of etomidate in a solid buccal dosage form in dogs.
• To determine the permeability and absorption rate of etomidate through the buccal mucosa.

Main Methods:

• A solid buccal dosage form containing 50 mg of etomidate was prepared.
• Dogs received both intravenous and buccal etomidate on separate occasions.
• Pharmacokinetic analysis, including model-dependent constrained numerical deconvolution, was performed on serum etomidate concentrations.

Main Results:

• The mean maximal serum etomidate concentration after buccal administration was 239 ng/mL, reached at 12.5 minutes.
• The peak absorption rate into systemic circulation was 832 µg/min, with 90% absorption occurring within 15 minutes.
• The apparent transbuccal mucosal permeability coefficient was 9.1 x 10⁻⁴ cm/s, and bioavailability was approximately 13.6%–16.6%.

Conclusions:

• Etomidate exhibits high permeability across the canine buccal mucosa.
• The rapid onset and offset of buccal absorption suggest potential for titratable etomidate delivery via this route.