Using Umbilical Cord Tissue to Identify Prenatal Exposure to Fentanyl and Other Commonly Abused Drugs

Background: Prenatal exposure to fentanyl may lead to Neonatal Abstinence Syndrome (NAS), a constellation of symptoms observed when newborns begin withdrawing from addictive substances such as opioids. The use of umbilical cord tissue segments (UC) for newborn toxicology has been increasing due to its apparent long detection window, sensitivity, and ease of collection. However, very little has been reported in the literature concerning the prevalence of in utero exposure to fentanyl and co-exposure with other commonly abused substances. Specific aim: The specific aims of this retrospective study are twofold. We will report prevalence of neonatal exposure to fentanyl for a nationwide high-risk population using UC submitted to a national reference laboratory for routine forensic toxicology analysis and the co-exposure patterns observed for these fentanyl-exposed neonates. Methods: A secondary analysis was performed using historical data for UC received between January 1, 2020 and December 31, 2020 for routine forensic toxicology analysis. Results: During the study period, our laboratory received 23,104 UC for analysis and 9667 (41.8%) of those UC were positive for at least one drug. The prevalence of fentanyl detection was 1.9% (n = 429). Of these 429 specimens there were 407 UC where both fentanyl and norfentanyl were detected. There were 14 UC where only fentanyl was detected and 8 UC where only norfentanyl was detected. When detected, the median concentrations of fentanyl and norfentanyl were 4029 pg/g (IQR: 1696, 9230 pg/g) and 10,756 pg/mg (IQR: 3925, 25,288 pg/g), respectively. Of the 429 positive fentanyl and/or norfentanyl UC, 33 (7.7%) were only positive for fentanyl and/or norfentanyl. Of the 396 polypositive UC, morphine was the highest co-exposure with 243 UC (56.6%) being positive for both fentanyls and morphine. The second most prevalent co-exposure observed was methamphetamine/amphetamine (n = 173;40.3%) followed by cannabinoids (n = 113;26.3%) and benzoylecgonine (cocaine metabolite;n = 106;24.7%). Conclusions: Nonmedical use of fentanyl is an alarming trend in this country including this maternal demographic reported here. Fentanyl was typically found with other commonly abused substances.

An update on placental drug transport and its relevance to fetal drug exposure

Pregnant women are often complicated with diseases that require treatment with medication.Most drugs administered to pregnant women are off-label without the necessary dose,efficacy,and safety information.Knowledge concerning drug transfer across the placental barrier is essential for understanding fetal drug exposure and hence drug safety and efficacy to the fetus.Transporters expressed in the placenta,including adenosine triphosphate(ATP)-binding cassette efflux transporters and solute carrier uptake transporters,play important roles in determining drug transfer across the placental barrier,leading to fetal exposure to the drugs.In this review,we provide an update on placental drug transport,including in vitro cell/tissue,ex vivo human placenta perfusion,and in vivo animal studies that can be used to determine the expression and function of drug transporters in the placenta as well as placental drug transfer and fetal drug exposure.We also describe how the knowledge of placental drug transfer through passive diffusion or active transport can be combined with physiologically based pharmacokinetic modeling and simulation to predict systemic fetal drug exposure.Finally,we highlight knowledge gaps in studying placental drug transport and predicting fetal drug exposure and discuss future research directions to fill these gaps.