141: Use of Naltrexone in treating pregnant women with opioid use disorder (OUD)

Abstract

Our designated obstetric OUD clinic offers opiate detoxification. If fully detoxed, naltrexone is offered. Naltrexone protocol requires the patient be opiate free for at least 7 days with 2 negative drug screens. A daily 50 mg dose is used that is adjusted near delivery. To date, only a few retrospective studies on naltrexone implant use during pregnancy are in print. The study objective was to prospectively evaluate the use of naltrexone in pregnancy. Prospective study that collected data on all pregnant women who started naltrexone after opiate detoxification. Data collection included GA at full detoxification, GA at naltrexone initiation, fetal response to the drug, pregnancy/newborn outcome, relapse rate, and paired maternal/cord blood levels for free naltrexone and 6-beta- naltrexol (20 patients). 108 pregnant patients started naltrexone during the study period. No relapses occurred in the 7-day no-treatment window prior to drug initiation. 82 (76%) patients were on naltrexone to delivery and no neonates had NAS. 4 newborns had NAS in the 26 cases that stopped naltrexone prior to delivery. Primary reasons for stopping naltrexone were headache (8) and “did not think they needed it” (11). 57 (53%) cases were started after 24 weeks gestation and had continuous fetal monitoring for 60 minutes during the first dose and no changes in FHR were seen. For the 51 cases < 24 weeks, no changes were seen in the FHR by auscultation or ultrasound during first dosage administration. 21 (19%) started naltrexone in the first trimester (<13 weeks) and no fetal anomalies occurred. No cases of SAB or IUFD occurred in the 108 pregnancies. 12 (11%) patients spontaneously delivered prior to 37 weeks gestation. Cord blood levels for naltrexone and 6-beta-naltrexol matched maternal levels (Table); no levels were elevated; and values were undetected if naltrexone was discontinued more than 60 hours prior to delivery. This is the first prospective study and largest to date on the use of naltrexone in pregnancy. The drug crosses the placenta; maternal and fetal levels are concordant; and the drug clears quickly. The drug is well-tolerated by both mother and fetus and newborns do not experience NAS if the mother is on naltrexone to delivery. These data demonstrate that the use of naltrexone is a viable option for managing OUD in pregnancy.