The Quantitative Analysis of 1- -Acetylmethadol and Its Principal Metabolites in Biological Specimens by Gas Chromatography-Chemical Ionization-Multiple Ion Monitoring Mass Spectrometry

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Abstract
1-α-acetylmethadol (LAAM) is a new drug under development for the treatment of heroin dependence. A new analytical method applicable to the accurate biodispositional study of the drug and its metabolites is described and critically discussed in this report. The procedure involves sample preparation and direct organic solvent extraction using n-butyl chloride, amide derivatization by molecular rearrangement, and gas chromatography-chemical ionization mass spectrometry-selected ion monitoring, with methane as the carrier and ammonia as reagent gases. Deuterated (d3) stable isotopes of LAAM and its metabolites are used as internal standards. The method is free from qualitative interferences and has quantitative sensitivity to 5 ng/ml for 2.0 ml samples with 10–15% accuracy and precision in the range 5–100 ng/ml; and 2–5% at concentrations up to 750 ng/ml. Specimens of plasma, whole blood, urine, bile, brain, liver, and other visceral samples have been successfully analyzed, as well as in vitro preparations such as hepatic microsomes. By appropriate data processing, the method lends itself to routine analysis and high volume work; even manually the method is capable of at least 50 samples per week. A simplified procedure for the analysis of LAAM and its metabolites in urine only is also presented and discussed. All of the work is described in sufficient detail to permit other workers to set up and use the methods.