Analysis of methadone and its primary metabolite in meconium.

Methods for analysis of methadone and its principal metabolite, 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP) in meconium, based on fluorescence polarization immunoassay (FPIA) and high-performance liquid chromatography (HPLC) and diode array detection were developed. Meconium and urine samples of 16 neonates from 15 methadone-using mothers were analyzed. Because of the lower detection limit and the possibility of coanalyzing EDDP, meconium analysis with HPLC for detecting methadone use is very much preferable to FPIA. Identical results were obtained with HPLC analysis for both matrices: methadone or EDDP or both could be detected in the urine and meconium samples from 15 children. The amount of EDDP in meconium was much higher than the amount of methadone (ratio, 9.6). EDDP only was detected in eight of the meconium samples. A positive correlation was found between the methadone dose of the mothers and the methadone concentration in meconium, but not with the EDDP concentration in meconium.