Genetic determinants of fetal opiate exposure and risk of neonatal abstinence syndrome: Knowledge deficits and prospects for future research

Decreased myelin-related gene expression in the nucleus accumbens during spontaneous neonatal opioid withdrawal in the absence of long-term behavioral effects in adult outbred CFW mice

Prenatal opioid exposure is a major health concern in the United States, with the incidence of neonatal opioid withdrawal syndrome (NOWS) escalating in recent years. NOWS occurs upon cessation of in utero opioid exposure and is characterized by increased irritability, disrupted sleep patterns, high-pitched crying, and dysregulated feeding. The main pharmacological strategy for alleviating symptoms is treatment with replacement opioids. The neural mechanisms mediating NOWS and the long-term neurobehavioral effects are poorly understood. We used a third trimester-approximate model in which neonatal outbred pups (Carworth Farms White; CFW) were administered once-daily morphine (15 mg/kg, s.c.) from postnatal day (P) day 1 through P14 and were then assessed for behavioral and transcriptomic adaptations within the nucleus accumbens (NAc) on P15. We also investigated the long-term effects of perinatal morphine exposure on adult learning and reward sensitivity. We observed significant weight deficits, spontaneous thermal hyperalgesia, and altered ultrasonic vocalization (USV) profiles following repeated morphine and during spontaneous withdrawal. Transcriptome analysis of NAc from opioid-withdrawn P15 neonates via bulk mRNA sequencing identified an enrichment profile consistent with downregulation of myelin-associated transcripts. Despite the neonatal behavioral and molecular effects, there were no significant long-term effects of perinatal morphine exposure on adult spatial memory function in the Barnes Maze, emotional learning in fear conditioning, or in baseline or methamphetamine-potentiated reward sensitivity as measured via intracranial self-stimulation. Thus, the once daily third trimester-approximate exposure regimen, while inducing NOWS model traits and significant transcriptomic effects in neonates, had no significant long-term effects on adult behaviors.

Assessing Neonatal Opioid Withdrawal Syndrome Severity as a Function of Maternal Buprenorphine Dose and Umbilical Cord Tissue Concentrations

BACKGROUND

Infants born to mothers with opioid use disorder (OUD) and prenatally treated with buprenorphine have a significantly lower incidence of neonatal opioid withdrawal syndrome (NOWS), its treatment duration, and hospital length of stay compared with methadone. However, risk of NOWS remains and clinicians continue to lack an objective methodology to predict NOWS severity among these infants.

OBJECTIVE

The purpose of this study was to assess the relationship between buprenorphine exposure, umbilical cord tissue (UCT) concentrations, and NOWS development and severity.

METHODS

A single-center retrospective observational cohort study from March 2018 through June 2020 of newborns exposed to buprenorphine in utero. Associations between quantified buprenorphine exposure, neonatal UCT concentrations, NOWS diagnosis, and severity were made using regression analyses.

RESULTS

A total of 24 mothers and 25 neonates were included. Length of maternal buprenorphine therapy (months) positively correlated to norbuprenorphine (r² = 0.234, P = 0.019) and buprenorphine + norbuprenorphine UCT concentrations (r² = 0.203, P = 0.031). A positive relationship was seen between active metabolite concentrations and cumulative morphine dose (mg/kg) for treatment of severe NOWS (r² = 0.471, P = 0.007). A 0.36 ng/g buprenorphine + norbuprenorphine UCT (CI = 0.002-0.72, P = 0.049) equated in a 1-point increase in modified peak Finnegan score.

CONCLUSION AND RELEVANCE

Buprenorphine and norbuprenorphine UCT concentrations can allow for quantification of in utero fetal exposure and demonstrate an association with a longer duration of exposure with the severity and treatment of NOWS in exposed infants.

Neonatal outcomes of preterm infants with in-utero exposure to drugs of substance use: US national data

BACKGROUND

Infants exposed prenatally to drugs of substance use are at increased risk for seizures, strabismus, feeding difficulty, and neurodevelopmental delays. Exposed preterm infants may have additional morbidities related to prematurity. There is limited literature on national outcomes of preterm infants exposed to drugs of substance use. We aimed to evaluate the trends and neonatal outcomes of preterm infants born in the USA who were exposed in-utero to drugs of substance use.

METHODS

Retrospective cohort study of preterm live born (<37 weeks gestation) exposed in-utero to opioids, hallucinogens, or cocaine in the Healthcare Cost and Utilization Project database from 2002 to 2017. Neonatal outcomes were identified using international classification of diseases 9&10 codes.

RESULTS

Of the 54,469,720 live-born infants, 7.7% (4,194,816) were preterm, and 58 679 (1.4%) were exposed in-utero to maternal opioids/hallucinogens (n = 39,335) or cocaine (n = 19,344). There was a trend for increased exposure to opioids/hallucinogens (Z score = 76.14, p < 0.001) during the study period. Exposed preterm infants had significantly more neurological anomalies, intra-ventricular hemorrhage and periventricular leukomalacia (p < 0.001).

CONCLUSIONS

There was a trend for increased in-utero exposure to opioids and hallucinogens in the preterm infants in the USA. Exposed preterm infants had more neurological morbidities.

Integrated in a systems pharmacology approach, pharmacogenetics holds the promise for personalized medicine in neonates

Tweetable abstract Integrated in a systems pharmacology approach, pharmacogenetics holds the promise for personalized medicine in neonates. This has been illustrated for some diseases specific to neonates.

Prenatal opioid-exposed infant extracellular miRNA signature obtained at birth predicts severity of neonatal opioid withdrawal syndrome

Prenatal opioid exposure (POE) is commonly associated with neonatal opioid withdrawal syndrome (NOWS), which is characterized by a broad variability in symptoms and severity. Currently there are no diagnostic tools to reliably predict which infants will develop severe NOWS, while risk stratification would allow for proactive decisions about appropriate clinical monitoring and interventions. The aim of this prospective cohort study was to assess if extracellular microRNAs (miRNAs) in umbilical cord plasma of infants with POE could predict NOWS severity. Participants (n = 58) consisted of pregnant women receiving medications for opioid use disorder and their infants. NOWS severity was operationalized as the need for pharmacologic treatment and prolonged hospitalization (≥ 14 days). Cord blood miRNAs were assessed using semi-quantitative qRT-PCR arrays. Receiver operating characteristic curves and area under the curve (AUC) were estimated. The expression of three miRNAs (miR-128-3p, miR-30c-5p, miR-421) predicted need for pharmacologic treatment (AUC: 0.85) and prolonged hospitalization (AUC: 0.90). Predictive validity improved after two miRNAs (let-7d-5p, miR-584-5p) were added to the need for pharmacologic treatment model (AUC: 0.94) and another two miRNAs (let-7b-5p, miR-10-5p) to the prolonged hospitalization model (AUC: 0.99). Infant cord blood extracellular miRNAs can proactively identify opioid-exposed neonates at high-risk for developing severe NOWS.

Racial differences in opioid withdrawal syndrome among neonates with intrauterine opioid exposure

BACKGROUND

The aim of this study was to investigate the association between race and severe neonatal opioid withdrawal syndrome (NOWS) in infants exposed to intrauterine opioids.

METHODS

This is a prospective observational study on intrauterine opioid-exposed term infants. Exposure to opioids was based on maternal disclosure, urine, or umbilical cord drug screening. Severe NOWS was defined based on modified Finnegan scoring and the need for pharmacological intervention.

RESULTS

One hundred and fifty mother-infant pairs, 60 Black and 90 White with history of opioid exposure during pregnancy, were included. More White than Black infants developed NOWS that required pharmacological treatment, 70 vs. 40%: RR = 1.75 (1.25-2.45). In adjusted analysis, there was no significant association between race and the development of severe NOWS in mothers who attended opioid maintenance treatment program (OMTP). However, in mothers who did not attend OMTP, White race remained a significant factor associated with the development of severe NAS, RR = 1.69 (1.06, 2.69).

CONCLUSIONS

Severe NOWS that required pharmacological intervention was significantly higher in White than in Black infants born to mothers who did not attend OMTP. Larger studies are needed to evaluate the association between social as well as genetic factors and the development of NOWS.

IMPACT

There is a significant association between race and development of severe NOWS.

Opioid Treatment for Neonatal Opioid Withdrawal Syndrome: Current Challenges and Future Approaches

Chronic intrauterine exposure to psychoactive drugs often results in neonatal opioid withdrawal syndrome (NOWS). When nonpharmacologic measures are insufficient in controlling NOWS, morphine, methadone, and buprenorphine are first-line medications commonly used to treat infants with NOWS because of in utero exposure to opioids. Research suggests that buprenorphine may be the leading drug therapy used to treat NOWS when compared with morphine and methadone. Currently, there are no consensus or standardized treatment guidelines for medications prescribed for NOWS. Opioids used to treat NOWS exhibit large interpatient variability in pharmacokinetics (PK) and pharmacodynamic (PD) response in neonates. Organ systems undergo rapid maturation after birth that may alter drug disposition and exposure for any given dose during development. Data regarding the PK and PD of opioids in neonates are sparse. Pharmacometric methods such as physiologically based pharmacokinetic and population pharmacokinetic modeling can be used to explore factors predictive of some of the variability associated with the PK/PD of opioids in newborns. This review discusses the utility of pharmacometric techniques for enhancing precision dosing in infants requiring opioid treatment for NOWS. Applying these approaches may contribute to optimizing the outcome by reducing cumulative drug exposure, mitigating adverse drug effects, and reducing the burden of NOWS in neonates.

Pharmacogenomic Testing In Pediatrics: Navigating The Ethical, Social, And Legal Challenges

For the past several years, the implementation of pharmacogenetic (PGx) testing has become widespread in several centers and clinical practice settings. PGx testing may be ordered at the point-of-care when treatment is needed or in advance of treatment for future use. The potential benefits of PGx testing are not limited to adult patients, as children are increasingly using medications more often and at earlier ages. This review provides some background on the use of PGx testing in children as well as mothers (prenatally and post-natally) and discusses the challenges, benefits, and the ethical, legal, and social implications of providing PGx testing to children.

Racial association and pharmacotherapy in neonatal opioid withdrawal syndrome

OBJECTIVE

To determine if racial differences are associated with Neonatal Opioid Withdrawal Syndrome (NOWS) severity.

STUDY DESIGN

A 10-year (2008-2017) retrospective cohort of infants ≥35 weeks gestation with prenatal exposure to opioids was included. The primary measure was the need for pharmacotherapy. Multivariable logistic regression and propensity score analysis were performed.

RESULTS

Among 345 infants with NOWS, 111 (32%) were black infants with 70% of them requiring pharmacotherapy as compared with 84% of white infants. Upon adjusting for significant covariates (methadone, benzodiazepine use, and gestational age), black infants were 57% less likely than whites to require pharmacotherapy (Odds ratio: 0.43, 95%CI: 0.22-0.80, p = 0.009). Similar results were observed with propensity score analysis.

CONCLUSIONS

Significant racial disparity observed may be secondary to genetic variations in opioid pharmacogenomics and/or extrinsic factors. Large-scale studies are warranted to include race in predictive models for early pharmacological intervention.

Prescription opioid use in pregnancy

Prescription medications, including opioid analgesics, are increasingly prescribed in Australia and internationally. More women are presenting in pregnancy with prescription opioid use which can potentially cause harm to the mother and fetus. This article outlines the different types of prescription opioids, defines how prescription opioid use disorder presents clinically and suggests a rational clinical approach to assess and manage patients in the context of pregnancy and their infants.

The Genomics of Neonatal Abstinence Syndrome

Significant variability has been observed in the development and severity of neonatal abstinence syndrome (NAS) among neonates exposed to prenatal opioids. Since maternal opioid dose does not appear to correlate directly with neonatal outcome, maternal, placental, and fetal genomic variants may play important roles in NAS. Previous studies in small cohorts have demonstrated associations of variants in maternal and infant genes that encode the μ-opioid receptor (OPRM1), catechol-O-methyltransferase (COMT), and prepronociceptin (PNOC) with a shorter length of hospital stay and less need for treatment in neonates exposed to opioids in utero. Consistently falling genomic sequencing costs and computational approaches to predict variant function will permit unbiased discovery of genomic variants and gene pathways associated with differences in maternal and fetal opioid pharmacokinetics and pharmacodynamics and with placental opioid transport and metabolism. Discovery of pathogenic variants should permit better delineation of the risk of developing more severe forms of NAS. This review provides a summary of the current role of genomic factors in the development of NAS and suggests strategies for further genomic discovery.

Clinical pharmacology of analgosedatives in neonates: ways to improve their safe and effective use

OBJECTIVES

To propose approaches tailored to the specific needs of neonates, such as structured product development programmes, with the ultimate goal to improve the safe and effective use of analgosedatives in these fragile patients.

KEY FINDINGS

The feasibility and relevance of a structured product development programme in neonates (optimal study design based on preliminary data; model development; internal, external and prospective evaluation; an individualized dosing regimen; long-term safety; pharmacogenetics) are illustrated for the use of morphine. Based on changes in clinical practices, similar development plans are in progress for short-acting analgosedatives such as propofol, but are in need of tailored pharmacodynamic tools to assess and quantify effects. Furthermore, for drugs like paracetamol where there is already sufficient clinical pharmacology knowledge, attention needs to be given to long-term safety aspects. Finally, new covariates such as pharmacogenetics might further improve neonatal pain management, but clearly need to be integrated with other well-established covariates like age or weight.

SUMMARY

Product development programmes for analgosedatives in neonates are needed. These programmes should be tailored to their specific needs (short-acting sedation, pain relief), should include long-term safety and should incorporate the exploration of newer covariates like pharmacogenetics.

Predictors of neonatal abstinence syndrome in buprenorphine exposed newborn: can cord blood buprenorphine metabolite levels help?

BACKGROUND

Buprenorphine is a semi-synthetic opioid used for the treatment of opioid dependence. Opioid use, including buprenorphine, has been increasing in recent years, in the general population and in pregnant women. Consequently, there has been a rise in frequency of neonatal abstinence syndrome (NAS), associated with buprenorphine use during pregnancy. The purpose of this study was to investigate correlations between buprenorphine and buprenorphine-metabolite concentrations in cord blood and onset of NAS in buprenorphine exposed newborns.

METHODS

Nineteen (19) newborns who met inclusion criteria were followed after birth until discharge in a double-blind non-intervention study, after maternal consent. Cord blood and tissue samples were collected and analyzed by liquid chromatography-mass spectrometry (LC-MS) for buprenorphine and metabolites. Simple and multiple logistic regressions were used to examine relationships between buprenorphine and buprenorphine metabolite concentrations in cord blood and onset of NAS, need for morphine therapy, and length of stay.

RESULTS

Each increase in 5 ng/ml level of norbuprenorphine in cord blood increases odds of requiring treatment by morphine 2.5 times. Each increase in 5 ng/ml of buprenorphine-glucuronide decreases odds of receiving morphine by 57.7 %. Along with concentration of buprenorphine metabolites, birth weight and gestational age also play important roles, but not maternal buprenorphine dose.

CONCLUSIONS

LC-MS analysis of cord blood concentrations of buprenorphine and metabolites is an effective way to examine drug and metabolite levels in the infant at birth. Cord blood concentrations of the active norbuprenorphine metabolite and the inactive buprenorphine-glucuronide metabolite show promise in predicting necessity of treatment of NAS. These finding have implications in improving patient care and reducing healthcare costs if confirmed in a larger sample.