Transfer of cocaine and benzoylecgonine across the perfused human placental cotyledon

Cocaine and its metabolites in the placenta: a systematic review of the literature

It is clear that cocaine and cocaine metabolites are present in the placenta and may harm the fetus. The results of the experimental manipulation of cocaine exposure are not reported in the literature in a consistent manner. We conducted a systematic review of selected articles that demonstrated the analytical detection of cocaine and its metabolites in the placenta and that were published from January 1, 1956-June 30, 2011 using Medline, Toxline and Scopus databases. The collected data confirm that the placenta does not act as a barrier to fetal exposure, that cocaine quickly crosses the placenta and that one of the essential roles of the placenta is to metabolize cocaine during pregnancy. Our systematic review summarized the results showing that cocaine, benzoylecgonine and norcocaine are stored in the myometrium and the placental membrane and maintain continuous drug delivery to the amniotic fluid (and to the fetus) probably via diffusion.

Agreement of umbilical cord drug and cotinine levels with maternal self-report of drug use and smoking during pregnancy

OBJECTIVE

We undertook this study to assess the agreement between fetal umbilical cord drug levels and maternal self-report.

STUDY DESIGN

Cord samples were collected from 103 placentas after delivery as a subproject of the larger Pacific Research Center for Early Human Development (PRCEHD) study. These cord samples were then processed to obtain cord lysates and enzyme-linked immunosorbent assay (ELISA) performed for cotinine and illicit drugs. Levels of each of these substances were compared with clinical information.

RESULT

We found fair agreement between self-reported smoking and cotinine levels (κ = 0.26 (0.07 to 0.5)) as well as slight agreement with current drug use and positive drug levels (κ = 0.19 (-0.05 to 0.4)). Compared with maternal self-report, sensitivity of cotinine levels was 27% and specificity was 98%. Sensitivity of positive cord illicit drug levels was 32% and specificity was 85%.

CONCLUSION

Umbilical cords provide another independent measure of maternal drug use and are readily available. To our knowledge, this is the first study to measure cotinine levels in the umbilical cord tissue.

Rats exposed to cocaine during late gestation and early postnatal life show deficits in hippocampal pyramidal and granule cells in later life

In humans, the offspring of maternal cocaine misusers are known to have subtle cognitive and motor impairments in later life. It was therefore hypothesized that such exposure in animals would also affect the morphological structure of the brain. This possibility was investigated by exposing rats to cocaine between embryonic day 15 and postnatal day 6. Samples of the cocaine-exposed and control rats were killed for examination at 22 and 150 postnatal days of age. Stereological procedures (the Cavalieri principle together with the physical disector method) were utilized to estimate the total number of pyramidal and granule cells in defined regions of the hippocampal formation. At 22 days of age, the control offspring had about 373 000 pyramidal cells whereas the cocaine-treated animals only had about 310,000 cells in the CA1 + CA2 + CA3 region. By 150 days of age the values were about 396,000 and 348,000, respectively. The differences between age-matched groups were statistically significant. There were about 626,000 and 687,000 dentate gyrus granule cells in the 22-day-old control and cocaine-treated groups, respectively. By postnatal day 150 the control rats had about 832,000 granule cells whilst the cocaine-treated rats had about 693,000. There was a significant main effect of age as well as group-age interaction in this measure. These results show that even moderate exposure to cocaine during the late gestation and early postnatal period in rats is a potent teratogen and can markedly influence the development of neurons in the hippocampal formation.

Detection of stimulant drugs of abuse in maternal and neonatal hair

Exposure to drugs of abuse, particularly during pregnancy, is difficult to ascertain. Presently, there is sparse information on gestational exposure and fetal effects to potentially toxic drugs such as methamphetamine (MA) and cocaine; two of the most prevalent abused stimulants in North America. The Motherisk laboratory at the Hospital for Sick Children routinely carries out analysis of MA and cocaine in adult and infant hair. All mother-child pairs in whom at least one had cocaine and/or benzoylecgonine (BE), or MA detected in hair were identified from the Motherisk database. Eleven mother-infant pairs with positive hair for MA were identified. One infant (9%) had a negative MA result with a positive maternal result. There was not any positive infant hair with negative maternal hair for MA. MA concentrations in mothers and infants correlated positively and were not significantly different. Median cocaine concentrations were tenfold higher in hair of the mothers compared to the infants. Thirty-nine (40%) infants had negative cocaine and BE with positive maternal results. Mothers whose infants were cocaine positive had median cocaine significantly higher than those whose infants were negative. Infants' cocaine in hair was positively correlated with maternal cocaine and BE. Infants' BE correlated with maternal cocaine and BE concentrations. Fetal hair grows during the last trimester of pregnancy; therefore a positive neonatal hair result indicates maternal use after pregnancy is known, a strong indicator of maternal addiction. To our knowledge, this is the first report on fetal exposure to MA during pregnancy showing transplacental transfer of the drug, with accumulation in fetal hair. Transplacental exposure to cocaine of babies of addicted mothers is highly variable. Further research is needed to understand the mechanisms leading to placental defense against cocaine.

Consequences of prenatal cocaine exposure in nonhuman primates

The extent to which cocaine abuse by pregnant women can affect development of their offspring remains a matter of significant debate. In large part, this is due to difficulties in accurate determination of the type, dose, and pattern of cocaine administration by drug abusing women as well as to difficulties in controlling for a wide range of potentially confounding variables, such as other drugs used, race, socioeconomic status, and level of prenatal care. On this background, examination of the effects of prenatal cocaine exposure in highly controlled nonhuman primate models represents an important complement to the human research. The present review summarizes the data obtained in several different rhesus monkey models of cocaine exposure in utero. These data demonstrate the potential of prenatal cocaine exposure to interfere with structural and biochemical development of the brain leading to behavioral deficits at birth and/or during adulthood. However, the differences in the outcomes between individual models also suggest that the specific types and severity of cocaine effects are likely dependent on the route, dose, gestational period, and daily pattern of administration.

Fetal effects of cocaine: an updated meta-analysis

BACKGROUND

A very large number of women in the reproductive age group consume cocaine, leading to grave concerns regarding the long term health of millions of children after in utero exposure. The results of controlled studies have been contradictory, leading to confusion, and, possible, misinformation and misperception of teratogenic risk.

OBJECTIVE

To systematically review available data on pregnancy outcome when the mother consumed cocaine.

METHODS

A meta-analysis of all epidemiologic studies based on a priori criteria was conducted. Comparisons of adverse events in subgroups of exposed vs. unexposed children were performed. Analyses were based on several exposure groups: mainly cocaine, cocaine plus polydrug, polydrug but no cocaine, and drug free.

RESULTS

Thirty three studies met our inclusion criteria. For all end points of interest (rates of major malformations, low birth weight, prematurity, placental abruption, premature rupture of membrane [PROM], and mean birth weight, length and head circumference), cocaine-exposed infants had higher risks than children of women not exposed to any drug. However, most of these adverse effects were nullified when cocaine exposed children were compared to children exposed to polydrug but no cocaine. Only the risk of placental abruption and premature rupture of membranes were statistically associated with cocaine use itself.

CONCLUSIONS

Many of the perinatal adverse effects commonly attributed to cocaine may be caused by the multiple confounders that can occur in a cocaine using mother. Only the risk for placental abruption and PROM could be statistically related to cocaine. For other adverse effects, additional studies will be needed to ensure adequate statistical power.

Dose-related differences in the distribution of cocaine in the maternal-fetoplacental compartments in rats

Our goals were to examine whether a high dose of cocaine to causing CNS toxic manifestations in the pregnant rats influences the delivery of cocaine to the fetus, and whether the non-placental compartments have a significant role in the distribution of cocaine to the fetal tissues. Either a low or high dose of cocaine was infused intravenously to near-term pregnant rats. Arterial blood pressure and heart rate were monitored. Cardiac output and uterine and placental blood flows were measured by using radiolabeled microspheres. Plasma and tissue samples were obtained from the mother, placenta, and fetus and analyzed for cocaine and its metabolites via capillary gas chromatography/mass spectrometry. A high dose of cocaine induced convulsions that were accompanied by increased arterial blood pressure and decreased uteroplacental blood flow. However, the distribution pattern of cocaine and metabolites in the mother and fetus were similar between the high and low dose groups. Considerable amounts of cocaine and its metabolites were in the placenta. Previously ignored non-placental tissues, such as the amnion and myometrium appear to be a significant source for cocaine accumulation in the fetus.

Liquid chromatography--tandem mass spectrometry analysis of cocaine and its metabolites from blood, amniotic fluid, placental and fetal tissues: study of the metabolism and distribution of cocaine in pregnant rats

The ability to simultaneously quantitate cocaine and its 12 metabolites from pregnant rat blood, amniotic fluid, placental and fetal tissue homogenates aids in elucidating the metabolism and distribution of cocaine. An efficient extraction method was developed to simultaneously recover these 13 components using underivatized silica solid-phase extraction (SPE) cartridges. The overall recoveries for cocaine and its metabolites were studied from pregnant rat blood (47-100%), amniotic fluid (61-100%), placental homogenate (31-83%), and fetal homogenate (39-87%). Extraction of the samples using silica is not classical SPE, but rather allows for the concentration of the sample into a small volume prior to injection and the removal of the proteins due to their strong interaction with the active silica surface. A positive ion mode electrospray ionization liquid chromatography-tandem mass spectrometry (LC-MS-MS) method was used and validated to simultaneously quantitate cocaine and 12 metabolites from these four biological matrices. A gradient elution method with a Zorbax XDB C8 reversed-phase column was used to separate the components. Multiple reaction monitoring (MRM) of a product ion arising from the corresponding precursor ion was used in order to enhance the selectivity and sensitivity of the method. Low background noise was observed from the complex biological matrices due to efficient SPE and the selectivity of the MRM mode. Linear calibration curves were generated from 0.01 to 2.50 ppm. The method also showed high intra-day (n =3) and inter-day (n=9) precision (% RSD) and accuracy (% error) for all components. The limits of detection (LODs) for the method ranged from 0.15 to 10 ppb. The LODs of cocaine and its major metabolites were less than 1 ppb from all four biological matrices. This method was applied to the study of the metabolism and distribution of cocaine in pregnant rats following intravenous infusion to a steady state plasma drug concentration. The following results were observed in the pregnant rat study: (1) the observations correlated strongly with the previous literature data on cocaine metabolism and distribution, (2) cocaine and norcocaine accumulated in the placenta, (3) arylhydroxylation of cocaine was a major metabolic pathway, (4) para-arylhydroxylation of cocaine was favored over meta-arylhydroxylation in rats and (5) accumulation of cocaine and its major metabolites was observed in the amniotic fluid.

The transplacental transfer of the macrolide antibiotics erythromycin, roxithromycin and azithromycin

OBJECTIVE

To investigate the transplacental transfer of the macrolide antibiotics erythromycin, roxithromycin and azithromycin.

METHODS

Twenty-one term placentas were obtained with maternal consent immediately after delivery and a two-hour nonrecirculating perfusion of a single placental cotyledon was performed. Erythromycin (2 microg/mL), roxithromycin (2 microg/mL) and azithromycin (0.3 microg/mL) were infused to the maternal inflow at a constant rate, with antipyrine as a reference compound, and their appearance in the fetal circulation was followed. Drug concentrations were measured by high performance liquid chromatography for 120 min.

RESULTS

The mean transplacental transfers (TPT(SS)) for erythromycin, roxithromycin and azithromycin were 3.0%, 4.3% and 2.6%, respectively, calculated as the ratio between the steady state concentrations in fetal venous and maternal arterial sides. Similar results were obtained when the TPT was calculated as the absolute amount of drug transferred across the placenta during 2-hour perfusion (TPT(A)). No significant differences were found among the three macrolides in TPT(SS) (P = 0.39) or TPT(A) (P = 0.35). The TPT(SS) of erythromycin, roxithromycin and azithromycin were 41%, 35% and 32% of the freely diffusable reference compound antipyrine, respectively. Steady state was reached in 60 minutes in each perfusion indicating sufficient perfusion time.

CONCLUSION

The limited transplacental transfer of erythromycin, roxithromycin and azithromycin suggests compromised efficacy in the treatment of fetal infections. On the other hand, the placenta seems to produce an effective barrier reducing the fetal exposure when these three macrolides are used to treat maternal infections.

Transfer of morphine across the human placenta and its interaction with naloxone

The purpose of this investigation was to measure the transfer rate and clearance of morphine across the placenta with and without naloxone. Term human placental cotyledons were perfused in vitro. The placenta was perfused with 50 ng/mL of morphine in the absence (n=4) and presence (n=5) of 100 ng/mL of naloxone. Maternal and fetal samples were collected. Student's t-test or one-way repeated measures ANOVA were used for all comparisons. The maternal-to-fetal morphine transfer rate was 0.73+/-0.44 ng/mL/min in the morphine and 0.69+/-0.26 ng/mL/min in the morphine-naloxone experiments (p=0.89). The clearance of morphine was 0.89+/-0.39 mL/min without naloxone and 0.87+/-0.27 mL/min with naloxone (p=0.92). Final morphine concentrations in the morphine experiments were 9.78+/-6.17 ng/mL (maternal) and 3.43+/-2.14 ng/mL (fetal) and 10.04+/-3.89 ng/mL (maternal) and 4.16+/-1.64 ng/mL (fetal) in the morphine-naloxone experiments. Morphine readily crosses the term human placenta. Naloxone does not alter placental transfer or clearance of morphine, suggesting that transfer across the placental barrier is not altered by changes in vascular resistance. Placental retention of morphine prolongs fetal exposure to morphine.

Cocaine induces cell death within the primate fetal cerebral wall

Transferase dUTP nick-end labelling (TUNEL) analysis was used to compare the occurrence of cell death in the cerebral wall of cocaine-exposed and drug-naïve monkey fetuses. The rhesus monkeys providing the drug-exposed fetuses received 10 mg/kg of cocaine orally (in fruit treats) in the morning and in the evening between pregnancy days 50 and 65. The control pregnant animals received fruit treats only. The fetuses were removed for analysis by Caesarean section 10 h after the last cocaine treatment. The sections of the cerebral wall from the cocaine-exposed fetuses contained significantly higher numbers of TUNEL-positive nuclei (counted either per section area or per 1000 unlabeled nuclei) than the matching sections from the drug-naïve fetuses. This elevation in the number of TUNEL-positive cells was observed through the entire depth of the fetal cerebral wall including its proliferative and intermediate zones, cortical plate and the marginal zone. The present study demonstrates that consumption of cocaine during pregnancy can result in increased occurrence of cell death in the developing cerebrum.

Maternal cocaine use and cigarette smoking in pregnancy in relation to amino acid transport and fetal growth

This review covers the weight of evidence that shows the association of cocaine and cigarette smoking in pregnancy with the impaired transplacental amino acid transport which might give rise to fetal growth restriction (IUGR). Vasoconstrictive effects of both cocaine and nicotine on the placental vasculature are clearly not the only cause for inhibition of placental amino acid uptake and transfer. In vitro studies strongly suggest that cocaine decreases the activity of placental amino acid transport system A and system N, and possibly system l and system y(+), while nicotine decreases the activity of system A. These findings are supported by cordocentesis studies in human IUGR pregnancies not resulting from drug abuse. More work is needed to be done in order to understand the potential additive or synergistic effect of cocaine and cigarette smoking on fetal growth and to determine the underlying cellular mechanisms of interaction with placental amino acid transporters.

The disposition of cocaethylene in rat maternal, placental, and fetal compartments

OBJECTIVE

The aim of this project was to examine the disposition of maternally administered cocaethylene in the fetus.

STUDY DESIGN

Pregnant rats with long-term catheter placement received an intravenous infusion of cocaethylene during a period of 30 minutes. At either the completion of the infusion or 6 hours after the infusion the fetuses were delivered by hysterotomy. Maternal and fetal blood and major tissue samples were obtained for assays of cocaethylene and its metabolites.

RESULTS

Cocaethylene was present in all samples obtained at the end of the infusion, but after 6 hours it was no longer detectable in the maternal and fetal systemic circulations. However, a substantial amount of cocaethylene was still present in the placenta on both the maternal and fetal sides, with the concentration on the maternal side being higher, indicating that the placenta stores cocaethylene. At the end of the infusion benzoylecgonine was found in all samples and the maternal concentrations were higher than the corresponding fetal concentrations. This order was reversed 6 hours after infusion. Extremely high concentrations of cocaethylene and benzoylecgonine were found in the amnion.

CONCLUSIONS

These results suggest that the placenta limits the transfer of cocaethylene to the fetus. The high affinity of this compound for extraplacental sites cannot be ignored.

Transplacental transfer and biotransformation studies of nicotine in the human placental cotyledon perfused in vitro

Our objective was to study the characteristics of transfer and biotransformation of nicotine in the human term placenta. Nicotine transfer was studied by dually perfusing an isolated cotyledon of the human placenta in vitro. Nicotine metabolism to cotinine was investigated in intact tissue during perfusion and in placental microsomal fractions. Following the addition of nicotine (40 ng/ml) to the maternal side of the placenta, distribution into placental tissue (0.43 +/- 0.13 ng/ml/min) was three times higher than transfer to the fetal side of the placenta (0.15 +/- 0.01 ng/ml/min). The steady-state maternal-to-fetal transfer of nicotine was approximately 90% that of antipyrine (a marker of flow-dependent transfer). There was no evidence of nicotine metabolism to cotinine by intact placental tissue or in microsomal fractions. The observation that nicotine readily crosses the human placenta with no evidence of metabolism suggests that nicotine has the potential to cause adverse affects on the developing fetus.

Transplacental pharmacokinetics of cocaine and benzoylecgonine in plasma and hair of rhesus monkeys

There is large variability in the rate and extent of fetal damage from cocaine in humans; however, the sources of such variability are not presently known. In order to study the relationship between maternal cocaine pharmacokinetics at the end of pregnancy and maternal or infant cocaine and benzoylecgonine hair concentrations at birth, ten rhesus monkeys were administered cocaine intramuscularly throughout pregnancy. Cocaine and benzoylecgonine hair concentrations were determined at birth and correlated with maternal pharmacokinetics during pregnancy. There were no correlations between either maternal cocaine Cmax or AUC0-infinity and maternal and infant hair cocaine or benzoylecgonine concentrations. There were no significant correlations between maternal hair benzoylecgonine concentrations and either maternal benzoylecgonine AUC0-120 (r = 0.60; P = 0.07) or benzoylecgonine Cmax (r = 0.60; P = 0.07). No correlations existed between infant hair benzoylecgonine concentrations and either maternal benzoylecgonine AUC0-120 (r = 0.30; P = 0.40) or benzoylecgonine Cmax (r = 0.30; P = 0.40). Also, no correlation was found between maternal cocaine dose and maternal or infant cocaine and benzoylecgonine hair concentrations. In comparison to toxicants such as nicotine and carbon monoxide for which there is a good correlation between maternal systemic exposure and neonatal concentrations, the lack of a similar relationship for cocaine is consistent with the role of the placenta in contributing to the variability in the amounts of cocaine reaching the fetus and hence, potentially to the risk of adverse fetal outcome.

Cocaine in pregnancy. Recent data on maternal and fetal risks

Cocaine continues to be abused during pregnancy, creating increased demands on the health care system. Epidemiology and basic science research have identified and confirmed risks of adverse maternal and fetal effects when cocaine is used during pregnancy. These effects of cocaine in pregnant women often are influenced by a number of confounding variables. This article reviews those cocaine effects as well as recent data, which examine in greater detail the risks of adverse outcomes of prenatal cocaine exposure during pregnancy.

Cocaine and cocaethylene binding to human placenta in vitro

OBJECTIVE

The aim of the study was to determine the binding profiles of cocaine and its ethyl homolog, cocaethylene, in human placenta.

STUDY DESIGN

Pooled whole human placental homogenates supplemented with either nonlabeled cocaine or cocaethylene over the concentration range 10 to 5000 x 10(-7) mol/L were submitted for equilibrium dialysis. Drug concentrations were measured by high-pressure liquid chromatography. Scatchard analysis of the data was performed.

RESULTS

A high-affinity, low-capacity binder was identified for cocaine (equilibrium constant of association, 3.68 x 10(5) L/mol; concentration of binding sites, 4.36 x 10(-6) mol/L) and for cocaethylene (equilibrium constant of association, 2.42 x 10(4) L/mol; concentration of binding sites, 2.65 x 10(-5) mol/L). Also, a low-affinity, high-capacity binder was noted for cocaine (equilibrium constant of association, 1.93 x 10(3) L/mol; concentration of binding sites, 5.28 x 10(-4) mol/L) and for cocaethylene (equilibrium constant of association, 2.15 x 10(2) L/mol; concentration of binding sites, 2.65 x 10(-3) mol/L). The concentration of binding sites expressed as moles per gram of placenta was as follows: high-affinity binder (cocaine, 4.36 x 10(-8); cocaethylene, 2.65 x 10(-7) and low-affinity binder (cocaine, 5.28 x 10(-6); cocaethylene, 2.65 x 10(-5). Up to 59% of cocaine and up to 42% of cocaethylene was bound.

CONCLUSION

Human placenta may serve as a depot for cocaine and cocaethylene.

Noninvasive methods for drug measurement in pediatrics

Infants and children present a special challenge to drug monitoring because the disposition of drugs differs from adults and because there are far fewer clinical studies designed for children than for adults. The excuse for this unfortunate situation is the imposition of severe technical and ethical constraints caused by blood sampling; however, in the past two decades, several new noninvasive methods to measure drugs have been tested and implemented in therapeutic drug monitoring. It is our hope that these new techniques will help advance the ability to diagnose and manage infants and young children.

Placental transfer of selected substances of abuse

The placenta was classically considered a barrier, but in 1957 this notion was shattered. This organ is only a selective filter and metabolic site. In this review, the placental transfer of the top 17 substances of abuse are analyzed. In the National Library of Medicine only 41 papers that documented placental transfer of the major substances of abuse could be located, and these data excluded approximately one-sixth of the most commonly abused substances. Nonetheless, it was possible to evaluate placental transfer of all substances of abuse based on their physical chemical properties. It is with despair that it must be reported that virtually all substances of abuse freely cross the placenta, exposing the embryo/fetus to whatever substances the mother may be using.

Cocaine inhibits hCG secretion by the human term placental cotyledon perfused in vitro

Cocaine has been shown to adversely affect pregnancy outcome in humans, but the mechanism(s) are not well understood. Using the technique of perfusing the human term placental cotyledon in vitro, we measured the rate of hCG appearance in the maternal circulation in the presence and absence of cocaine in the maternal circulation. At a dose of 0.80 microgram/mL, hCG secretion was reduced by 46%. This reduction in hCG concentration in the maternal circulation may effect normal steroidogenesis required to maintain pregnancy and may contribute to our understanding of the reproductive toxicology of cocaine.

A new placental enzyme in the metabolism of cocaine: an in vitro animal model

OBJECTIVE

The aim of this study was to analyze placental metabolism in a genetically controlled in vitro animal model.

STUDY DESIGN

Placentas from Sprague-Dawley rats were centrifuged, and microsomes were isolated. Four treatment groups were incubated with cocaine over four time periods: placental microsomes + cocaine, placental microsomes + diisopropyl fluorophosphate (an anticholinesterase) + cocaine, placental microsomes + cocaine + butyrylcholinesterase, and a blank (cocaine only). Gas chromatography was used to quantify cocaine (Limit of quantitation = 19 ng/ml) and metabolites. Gas chromatography/mass spectrometry was used to verify the identity of the metabolites.

RESULTS

Butyrylcholinesterase enhanced cocaine metabolism to ecgonine methyl ester. More than 40% of cocaine was metabolized to norcocaine by rat placental when diisopropyl fluorophosphate suppressed cocaine. Norcocaine is produced by hepatic N-demethylase action on methyl-bearing nitrogen in cocaine, suggesting that placenta and liver have this capacity. Gas chromatography/mass spectrometry was essential to the identification of norcocaine, because norcocaine is frequently not identified.

CONCLUSIONS

This biotransformation of cocaine to norcocaine may be a primary metabolic pathway induced in the cholinesterase-deficient placenta. This has clinical implications because norcocaine is ninefold more active physiologically than cocaine or ecgononine methylesterase.

Human placenta: a direct target for cocaine action

Use of cocaine during pregnancy is known to have harmful effects on the mother and her fetus. Currently available models describing the pathogenesis of these effects focus on the involvement of cocaine target systems, primarily the noradrenaline transporter, in the mother and the fetus. The placenta which lies between the mother and the fetus is considered only as a 'silent observer' in the whole process of cocaine-induced complications during pregnancy. Recent studies have, however, shown that the placenta expresses several cocaine target proteins such as the noradrenaline transporter, the serotonin transporter, and the sigma receptor. The functions of these proteins are significantly impaired in the presence of cocaine at concentrations known to exist in the plasma of cocaine users. These studies clearly show that the placenta itself is a direct target for cocaine action and that interaction of cocaine with its target proteins in the placenta plays an important role in the pathogenesis of cocaine-induced complications in the mother and her developing fetus.

Maternal cocaine use without evidence of fetal exposure

We report a case of lack of fetal exposure to cocaine and benzoylecgonine as evidenced by meconium and hair analysis, but exposure to nicotine and its metabolite cotinine, after extensive maternal use of cocaine and nicotine. These data suggest that the mode of maternal use of cocaine and individual differences in placental handling of the drug may protect some fetuses, and highlight the need to address interpatient variability.