Determination of sodium diethyldithiocarbamate (Imuthiol) and its S-methyl metabolite by gas chromatography—mass spectrometry : Use of deuteromethyl iodide derivatization

Abstract A gas-chromatographic—mass spectrometric method is described to measure the plasma concentration of sodium diethyldithiocarbamate (ditiocarb sodium, DEDTC-Na), the active ingredient of Imuthiol ® , a drug found to be active in the opportunistic infections occurring in AIDS, and its S-methyl metabolite. Plasma samples are treated with deuteromethyl iodide and DEDTC-Na is transformed into its deuteromethyl ester, which is then co-extracted with the S-methyl metabolite. Gas chromatography—mass spectrometry and selected-ion monitoring allow the specific determination of both compounds. Linear calibration curves were obtained up to 4000 ng/ml. This method has been succesfully applied for pharmacokinetic studies after Imuthiol and disulfiram, the dimer of DEDTC, were administered to humans.