Meperidine and normeperidine metabolism in the rhesus monkey.

Meperidine and its principle metabolite, normeperidine, were given intravenously to four non-human primates prior to cesarean delivery in an equivalent dose for human parturients. The status of the infants regarding neonatal depression was assessed at delivery. Repeated blood samples from both the mother and the neonate were obtained over a period of 4 days. The levels of meperidine and normeperidine were analyzed. The results showed that the metabolism of meperidine and normeperidine in the non-human primate was essentially the same as that observed in the human parturient. In addition, normeperidine appeared to be more toxic than meperidine to the neonate. Finally, there does not appear to be an evidence for neonatal metabolism of meperidine to normeperidine.