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Naltrexone Seems Effective For Opioid Use Disorder in Pregnancy

August 12, 2019

By Will Boggs MD

NEW YORK (Reuters Health) - Naltrexone may be effective for treating opioid use disorder (OUD) in pregnant women who choose to completely detoxify off opioid drugs, researchers report.

"How this study can change future practice is to give some pregnant women the option to choose how they are managed during the pregnancy, and naltrexone is a major form of medication-assisted treatment (MAT) that can be used that is not an opioid drug," Dr. Craig V. Towers of the University of Tennessee Medical Center, in Knoxville, told Reuters Health by email.

Three primary medications are currently recommended for MAT by the Substance Abuse and Mental Health Services Administration: methadone and buprenorphine, both opioid agonists that continue opioid-drug dependence but prevent cravings for illicit opioid drugs, and the opioid antagonist naltrexone, which can prevent cravings without producing dependence. Naltrexone has not been extensively studied in pregnancy because it requires full detoxification before it can be used.

Dr. Towers and colleagues compared the outcomes of 121 pregnant women who chose naltrexone pharmacotherapy MAT (after full detoxification) with those of 109 similar women who opted for continued opioid agonist (traditional) pharmacotherapy MAT.

The rates of positive toxicology screens for an opioid drug once opioid-drug free did not differ significantly between the naltrexone group (14/121, 11.6%) and the traditional MAT group (16/109, 14.7%).

Obstetrical outcomes did not differ between the groups, and there were no problems with pain-control management at delivery in the naltrexone group.

None of the neonates of mothers who were on naltrexone at delivery were treated for signs of neonatal abstinence syndrome (NAS), but 10 newborns of 34 women who discontinued naltrexone prior to delivery were treated for symptoms of NAS, the researchers report in the American Journal of Obstetrics and Gynecology, online July 31.

No changes were seen in fetal heart tracings during the 60 minutes of monitoring with the first dose of naltrexone in 64 women who started treatment at 24 weeks' gestation or later.

There were two neonates with anomalies in both treatment groups, including one with bilateral club feet and one with a small herniation of bowel into the umbilical cord in the naltrexone group, and one with cleft lip, no palate and one with a small congenital pulmonary airway malformation in the traditional group.

Mean birth weights and rates of birth weights below the 10th percentile did not differ between the groups.

"We found that the drug is excellent at preventing cravings for opioid drugs, which is what we need it to do," Dr. Towers said. "However, with the quick clearance, this means that a user can crave within 48 to 72 hours after stopping the drug and risk the possibility of relapse. Therefore, we tell all our patients that we successfully get on naltrexone about this finding, and reiterate that point each and every time we see them, to make sure they understand that they cannot stop the drug abruptly without us knowing."

"We need to let the mother choose which path she wants to follow," he said. "Give the mother the option, and if she successfully gets off opioid drugs or her MAT, naltrexone is an excellent drug that can be continued as a different form of MAT but with an anti-opioid effect. Also, once they are on naltrexone, they need to stay on it (oral or preferably the injection after delivery) for 18 to 24 months post-delivery."

"This study was not designed to evaluate the differences between opioid agonist MAT and medically supervised withdrawal during pregnancy," the researchers note. "Nevertheless, further research is needed in this area and naltrexone can play a role in this treatment process."

Dr. Cresta Wedel Jones of the University of Minnesota Medical School, in Minneapolis, who recently reviewed naltrexone pharmacotherapy during pregnancy, told Reuters Health by email, "I think that this study does begin a new conversation about the role of naltrexone as a safer treatment during pregnancy. In particular, if women are stable on naltrexone coming into pregnancy, these data suggest that this is a feasible option with no findings to suggest an increased risk of pregnancy complications from remaining on this treatment. It also provides evidence to support women who want to start naltrexone during their pregnancy as an alternative to methadone or buprenorphine."

"I am very interested in the long-term outcomes of the women who chose naltrexone treatment during the pregnancy, as (the study) notes outcomes only until the 14-day scheduled follow-up," she said. "Already at that time, 16 patients had returned to methadone/buprenorphine and 5 never returned for that visit. Other research identified the postpartum period as a time in which the risk of opioid overdose increases, and I would be interested to know how these women who were maintained on naltrexone did in the 6-12 weeks after delivery with regards to relapse and overdose."

"As a women's health care provider, I want to make sure that the treatments that we are providing for women during their pregnancy also position them for long-term recovery of health after delivery as well," said Dr. Jones, who was not involved in the study. "If outcomes after delivery treated with naltrexone therapy are similar to outcomes for women on continued methadone or buprenorphine after delivery, then naltrexone should be considered as a possible alternative which might reduce significantly the rate of neonatal opioid withdrawal syndrome."


Am J Obstet Gynecol 2019.

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