Quantitation Of The Local Anesthetic Dibucaine With Gas Chromatography / Mass Spectrometry

Abstract

A chemical ionization and an electron impact GC/MS assaying approach is presented for determining dibucaine concentrations in biological fluids. Both use deuterium-labeled drug as the internal standard and rely on the same sample extraction and sample preparation procedure. Under chemical ionization conditions (CH₄), the assaying limits are in the range of 1–80 ng/ml of serum. Under electron impact conditions, the analytical range is 20–800 ng/ml. The chemical ionization procedure has been found suitable for monitoring drug levels in man. One volunteer, who received a single 5-mg oral dose, showed peak serum drug concentrations of 23 ng/ml attained 2 hr after drug administration. The biologic half-life (ß phase) was 11 hr.

Key Words:

• Dibucaine
• Nupercaine^R
• local anesthetic
• gas chromatography / mass spectrometry (GC/MS)
• selected ion monitoring (SIM)
• half-life