Medical records for 75 neonates exposed to buprenorphine (n = 47) or methadone (n = 28) in utero who required treatment for NAS were examined. Time elapsed between birth and initiation of pharmacologic treatment was calculated for each neonate and time to treatment initiation compared between groups.
Median time to treatment initiation (hours:minutes, IQR) was significantly later in buprenorphine- vs. methadone-exposed neonates (71:02, 44:21-96:27 vs. 34:12, 21:00-55:41, respectively, p < .001). Estimates of mean time to treatment initiation from parametric analyses that adjusted for maternal and neonatal characteristics were very similar (73:10 (95 % CI: 61:00-87:18) vs. 42:36 (95 % CI: 33:06-53:30), respectively, p = .0005). This difference was not dependent on maternal age or neonatal sex, gestational age, or birth weight.
These findings confirm results from randomized clinical trials, adding generality to the observation that buprenorphine-exposed neonates require treatment significantly later than methadone-exposed neonates.