Cocaine abuse by pregnant women is increasingly recognized as causing serious health consequences for mother and newborn. To assess the placental transfer and fetal effects of cocaine, we studied its pharmacokinetics following intravenous administration to the pregnant ewe and fetus. Following bolus doses of 0.5-4.0 mg/kg to ewes, cocaine appeared within 30 s in fetal circulation, with peak concentrations occurring in 4-5 min. The disappearance of cocaine in the fetal plasma paralleled that in maternal plasma, suggesting that a rapid equilibrium of cocaine occurred between maternal and fetal compartments. The mean half-life of cocaine in the fetus across doses (4.4-5.0 min) was similar to that in the ewe (4.0-5.6 min). Plasma clearance of cocaine in the ewe did not appear to vary according to dose. The fetal exposure to cocaine, as indicated by the area under the fetal plasma concentration versus curve, was a linear function of maternal cocaine dose (r = 0.96, p < 0.01). These results demonstrate rapid placental transfer of cocaine after maternal administration in an animal model and rapid metabolism by mother and fetus.

We studied maternal and fetal blood pressure, heart rate, arterial blood gases and fetal behavioral state alterations in response to maternally administered cocaine hydrochloride in 11 pregnant sheep. Cocaine administration to the ewe caused a dose-dependent increase in maternal blood pressure and heart rate and in fetal blood pressure, and a decrease in fetal arterial oxygen tension. In the ewe, blood pressure changes corresponded linearly to dose administered (r = 0.88, p < 0.001). Blood pressure changes were correlated to peak plasma cocaine concentration in the ewe (r = 0.52, p < 0.01) and in the fetus (r = 0.43, p = 0.05). In addition, in 7 of 8 fetuses which had entered rapid eye movement (REM) sleep within 5 min of maternal cocaine administration, REM sleep was abruptly terminated either by the cocaine, fetal hypoxia or some other nonspecific event caused by the maternal cocaine administration. Maternal cocaine administration causes maternal and fetal hemodynamic alterations that have potential adverse effects in pregnancy.