Pragmatic, randomized, blinded trial to shorten pharmacologic treatment of newborns with neonatal opioid withdrawal syndrome (NOWS)

BACKGROUND

The incidence of maternal opioid use in the USA has increased substantially since 2000. As a consequence of opioid use during pregnancy, the incidence of neonatal opioid withdrawal syndrome (NOWS) has increased fivefold between 2002 and 2012. Pharmacological therapy is indicated when signs of NOWS cannot be controlled, and the objective of pharmacological therapy is to control NOWS signs. Once pharmacologic therapy has started, there is great variability in strategies to wean infants. An important rationale for studying weaning of pharmacological treatment for NOWS is that weaning represents the longest time interval of drug treatment. Stopping medications too early may not completely treat NOWS symptoms.

METHODS

This will be a pragmatic, randomized, blinded trial of opioid weaning to determine whether more rapid weaning, compared to slow wean, will reduce the number of days of opioid treatment in infants receiving morphine or methadone as the primary treatment for NOWS.

DISCUSSION

The proposed study is a pragmatic trial to determine whether a rapid-weaning intervention reduces the number of days of opioid treatment, compared to a slow-weaning intervention, and we powered the proposed study to detect a 2-day difference in the length of treatment. Hospitals will be able to use either morphine or methadone with the knowledge that we may find a positive treatment effect for both, one, or neither drugs.

TRIAL REGISTRATION

NCT04214834. Registered January 2, 2020.

Thalamocortical functional connectivity in infants with prenatal opioid exposure correlates with severity of neonatal opioid withdrawal syndrome

PURPOSE

Prenatal opioid exposure (POE) is a growing public health concern due to its associated adverse outcomes including neonatal opioid withdrawal syndrome (NOWS). The aim of this study was to assess alterations in thalamic functional connectivity in neonates with POE using resting-state functional magnetic resonance imaging (rs-fMRI) and identify whether these altered connectivity measures were associated with NOWS severity.

METHODS

In this prospective, IRB-approved study, we performed rs-fMRI in 19 infants with POE and 20 healthy control infants without POE. Following standard pre-processing, we performed seed-based functional connectivity analysis with the right and left thalamus as the regions of interest. We performed post hoc analysis in the prenatal opioid exposure group to identify associations of altered thalamocortical connectivity with severity of NOWS. P value of < .05 was considered statistically significant.

RESULTS

There were several regions of significantly altered thalamic to cortical functional connectivity in infants with POE compared to the healthy infants. Distinct regions of thalamocortical functional connectivity correlated with maximum modified Finnegan score. Association between thalamocortical connectivity and severity of NOWS was nominally modified by maternal psychological conditions and polysubstance use.

CONCLUSION

Our findings reveal prenatal opioid exposure-related alterations in thalamic functional connectivity in the infant brain that are correlated with severity of NOWS. Future studies may benefit from evaluation of thalamocortical resting state functional connectivity in infants with POE to help  stratify risk of long term neurodevelopmental outcomes.

Cardiorespiratory anomalies and increased brainstem microglia in a rat model of neonatal opioid withdrawal syndrome

Infants born with neonatal opioid withdrawal syndrome (NOWS) can display abnormal cardiorespiratory patterns including tachypnea, tachycardia, and impaired ventilatory responses to hypoxia (HVR) and hypercapnia (HCVR). Chronic morphine exposure is associated with increased midbrain microglial expression. Using a rat model of pre- and post-natal morphine exposure, we assessed cardiorespiratory features of NOWS (resting tachycardia and tachypnea) including the attenuated HVR and HCVR and whether they are associated with increased brainstem microglia expression. Pregnant rats (dams) received twice-daily subcutaneous injections of morphine (5 mg/kg) during the third (last) week of pregnancy to simulate 3rd trimester in utero opioid exposure. Offspring then received once-daily subcutaneous injections of morphine (0.5 mg/kg) until postnatal (P) day P10 days of age to simulate postnatal morphine therapy. Cardiorespiratory responses were assessed 24 h later (P11 days) following spontaneous withdrawal. Compared to saline-treated pups, morphine-exposed offspring exhibited tachycardia and tachypnea as well as an attenuated HVR and HCVR. Microglial cell counts were increased in the nucleus tractus solitarius (nTS), dorsal motor nucleus of the vagus (DMNV) and nucleus ambiguous (NAamb), but not the retrapezoid nucleus (RTN) or the non-cardiorespriatory region, the cuneate nucleus (CN). These data suggest that the cardiorespiratory features and autonomic dysregulation in NOWS infants may be associated with altered microglial function in specific brainstem cardiorespiratory control regions.

Maternal continuous oral oxycodone self-administration alters pup affective/social communication but not spatial learning or sensory-motor function

BACKGROUND

The broad use/misuse of prescription opioids during pregnancy has resulted in a surge of infants with Neonatal Opioid Withdrawal Syndrome (NOWS). Short-term irritability and neurological complications are its hallmarks, but the long-term consequences are unknown.

METHODS

A newly-developed preclinical model of oxycodone self-administration enables adult female rats to drink oxycodone (∼10/mg/kg/day) before and during pregnancy, and after delivery, and to maintain normal liquid intake, titrate dosing, and avoid withdrawal.

RESULTS

Oxycodone was detected in the serum of mothers and pups. Growth parameters in dams and pups and litter mass and size were similar to controls. There were no differences in paw retraction latency to a thermal stimulus between Oxycodone and Control pups at postnatal (PN) 2 or PN14. Oxycodone and Control pups had similar motor coordination, cliff avoidance, righting time, pivoting, and olfactory spatial learning from PN3 through PN13. Separation-induced ultrasonic vocalizations at PN8 revealed higher call frequency in Oxycodone pups relative to Control pups (p<0.031; Cohen's d=1.026). Finally, Oxycodone pups displayed withdrawal behaviors (p's<0.029; Cohen's d's>0.806), and Oxycodone males only vocalized more than Control pups in the first minute of testing (p's<0.050; Cohen's d's>.866). Significant effects were corroborated by estimation plots.

CONCLUSIONS

Our rat model of oral oxycodone self-administration in pregnancy shows exacerbated affect/social communication in pups in a sex-dependent manner but spared cognition and sensory-motor behaviors. This preclinical model reproduces selective aspects of human opioid use during pregnancy, enabling longitudinal analysis of how maternal oxycodone changes emotional behavior in the offspring.

Analgesia, Opioids, and Other Drug Use During Pregnancy and Neonatal Abstinence Syndrome

When opioid misuse rises in the United States, pregnant women and their neonates are affected. This article summarizes the use of Food and Drug Administration-approved products, including methadone, buprenorphine, and the combination formulation of buprenorphine and naloxone to treat adult opioid use disorder during the perinatal period. All labels include pregnancy, neonatal, and lactation information and note the accepted use of these medications during the perinatal period if the benefits outweigh the risks. A summary of the neonatal abstinence syndrome definition, its assessment tools, treatment approaches, and future genetic directions are provided.