Differences in the profile of neonatal abstinence syndrome signs in methadone- versus buprenorphine-exposed neonates.

Abstract

To compare the profile of signs of neonatal abstinence syndrome (NAS) in methadone- versus buprenorphine-exposed infants. Secondary analysis of NAS data from a multi-site, double-blind, double-dummy, flexible-dosing, randomized clinical trial. Data from a total of 129 neonates born to opioid-dependent women who had been assigned to receive methadone or buprenorphine treatment during pregnancy were examined. For 10 days after delivery, neonates (methadone = 72, buprenorphine = 57) were assessed regularly using a 19-item modified Finnegan scale. Data from neonates who required pharmacological treatment (methadone = 41, buprenorphine = 27) were included up to the time treatment was initiated. The incidence and mean severity of the total NAS score and each individual sign of NAS were calculated and compared between medication conditions, as was the median time until morphine treatment initiation among treated infants in each condition. Two NAS signs (undisturbed tremors and hyperactive Moro reflex) were observed significantly more frequently in methadone-exposed neonates and three (nasal stuffiness, sneezing, loose stools) were observed more frequently in buprenorphine-exposed neonates. Mean severity scores on the total NAS score and five individual signs (disturbed and undisturbed tremors, hyperactive Moro reflex, excessive irritability, failure to thrive) were significantly higher among methadone-exposed neonates, while sneezing was higher among buprenorphine-exposed neonates. Among treated neonates, methadone-exposed infants required treatment significantly earlier than buprenorphine-exposed infants (36 versus 59 hours postnatal, respectively). The profile of neonatal abstinence syndrome differs in methadone- versus buprenorphine-exposed neonates, with significant differences in incidence, severity and treatment initiation time. Overall, methadone-exposed neonates have a more severe neonatal abstinence syndrome.