m-hydroxy benzoylecgonine recovery in fetal guinea pigs

Recently, meta-hydroxybenzoylecgonine (m-OH BE) was identified by gas chromatography-mass spectroscopy during quantitative analysis for cocaine. Identification of m-OH BE in addition to the routinely identified benzoylecgonine by gas chromatography-mass spectroscopy confirmatory assays may increase detection of cocaine-exposed infants and decrease false negative results. However, it is not known whether m-OH BE is derived directly from benzoylecgonine or from hydroxylated cocaine, or whether this metabolite is produced in the fetus or transferred across the placenta from the maternal circulation. We quantitated the recovery of cocaine, benzoylecgonine, and m-OH BE from amniotic fluid, fetal meconium, fetal intestine, and maternal urine for up to 4 days after single dose administration of either cocaine or benzoylecgonine to pregnant time-bred guinea pigs. m-OH BE was recovered from meconium after maternal injections of cocaine and benzoylecgonine. There was no significant detection of m-OH BE from amniotic fluid or intestine and minimal recovery from maternal urine after either cocaine or benzoylecgonine administration. Detection of m-OH BE in meconium increased the identification of in utero exposed guinea pigs, and the greatest yield of m-OH BE from meconium occurred later than that observed for cocaine or benzoylecgonine.