Pharmacokinetics of acetylmethadols I: gas-liquid chromatographic determination of L-alpha-acetylmethadol and its major metabolites in plasma.

A gas chromatographic method is reported for simultaneously determining acetylmethadol, noracetylmethadol, and dinoracetylmethadol in plasma. Minimum detectable concentrations are 10 ng ml-1 for acetylmethadol using a flame ionization detector, and 5 and 25 ng ml-1 for noracetylmethadol and dinoracetylmethadol respectively using electron capture detection. Extraction efficiency is quantitative for acetylmethadol but lower for the metabolites. The method is useful for monitoring drug levels following therapeutic doses of acetylmethadol.