Kate Johnson

April 18, 2011

April 18, 2011 (Washington, DC) — Buprenorphine for the treatment of opioid dependence in pregnancy produces more favorable neonatal outcomes compared with methadone, according to 10 years of data from the University of Vermont in Burlington.

"We did see a significant reduction in the treatment of neonatal abstinence syndrome in the babies that were exposed to buprenorphine," said Marjorie Meyer, MD, from the university's Department of Obstetrics, Gynecology and Reproductive Science.

The retrospective cohort study examined 505 infants born between 2000 and 2010 whose mothers had received treatment for opioid dependence during pregnancy.

Overall, 233 infants had gestational exposure to methadone, whereas 267 were exposed to buprenorphine, Dr. Meyer reported here at the American Society of Addiction Medicine 42nd Annual Medical-Scientific Conference.

The study was not randomized, she explained, and reflected the clinic's trend during that decade toward increasing use of buprenorphine over methadone. In 2000, only 10% of pregnant, opioid-dependent patients were treated with buprenorphine, with this number increasing to 64% by 2010.

Across a number of outcomes, buprenorphine produced more favorable results than methadone, including a statistically significant reduction in cesarean section (27% vs 33%, P = .001), a nonsignificant reduction in preterm birth (11% vs 16%), a significant increase in birthweight (approximately 3100 vs 2700 g, P = .0001), and a significantly greater gestational age at delivery in the nonpreterm infants (40 vs 39 weeks, P = .001).

In addition, among newborns born at 37 weeks of gestation or more, there was a nonsignificant decrease of 1 day in hospital length of stay among the buprenorphine-exposed group (4 vs 5 days) and a significant reduction in treatment for neonatal abstinence syndrome (20% vs 43%, P = .001).

In a subgroup of infants tested for neurodevelopmental outcome at around 10 months, the methadone and buprenorphine groups were “basically equivalent and very reassuring in terms of being normal,” said Dr. Meyer.

She noted that one of the most striking statistics in the study was the rate of smoking, which reached more than 85% in the entire cohort.

"Birthweights were well below the median in both groups," she said, which speaks to the importance of addressing this addiction simultaneously.

Asked by Medscape Medical News to comment on the study, Jeffrey T. Junig, MD, PhD, said buprenorphine likely has benefits over methadone during pregnancy but that there are probably other factors that may partially explain the study results.

As a psychiatrist at the University of Wisconsin, Oshkosh, Student Health Service, assistant clinical professor of psychiatry at the Medical College of Wisconsin, and a private clinician in Fond du Lac, Wisconsin, Dr. Junig says he has guided about 30 opioid-dependent women through pregnancy and delivery using buprenorphine.

He says socioeconomic differences between patients treated at methadone treatment centers and buprenorphine-treated patients could explain some of the neonatal differences.

"Methadone treatment centers on average have higher numbers of patients with the most severe addictions — who likely have a higher incidence of poverty, homelessness, and other associated problems — like prostitution, use of multiple substances, cigarette and alcohol use," he said. These consequences of severe addiction also affect birth outcomes.

"To be on buprenorphine, a person has to function on a certain minimal level — the person must be free of opioids for more than 24 hours for the induction; for example; the person must keep appointments; the person must be able to save up money to pay for visits."

Dr. Meyer has disclosed no relevant financial relationships. Dr. Junig declared receiving speaker's fees from GlaxoSmithKline and Shire pharmaceuticals, but his work was not related to buprenorphine.

American Society of Addiction Medicine (ASAM) 42nd Annual Medical-Scientific Conference: Abstract P5. Presented April 15, 2011.

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