Received on May 7, 2007
Accepted on September 18, 2007

Drug Monitoring and Toxicology

Buprenorphine and Norbuprenorphine in Hair of Pregnant Women and Their Infants after Controlled Buprenorphine Administration

¹ Chemistry and Drug Metabolism Section, National Institute on Drug Abuse–Intramural Research Program, National Institutes of Health, Baltimore, MD
² Center for Human Toxicology, Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, UT
³ Chemistry and Drug Metabolism Section, National Institute on Drug Abuse–Intramural Research Program, National Institutes of Health, Baltimore, MD; Department of Biology, University of Pittsburgh at Titusville, Titusville, PA
⁴ Office of the Clinical Director, National Institute on Drug Abuse–Intramural Research Program, National Institutes of Health, Baltimore, MD
⁵ Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD
⁶ Reckitt Benckiser Pharmaceuticals, Inc., Richmond, VA

^* To whom correspondence should be addressed. E-mail: mhuestis{at}intra.nida.nih.gov.

Background: Buprenorphine is under investigation as a pharmacotherapeutic agent for treating opioid dependence in pregnant women. We hypothesized that there would be a relationship between the cumulative maternal dose of buprenorphine during pregnancy and the concentration of buprenorphine and norbuprenorphine in maternal and infant hair.

Methods: This study examined buprenorphine and norbuprenorphine concentrations in hair obtained from 9 buprenorphine-maintained pregnant women and 4 of their infants. Specimens were analyzed by liquid chromatography-tandem mass spectrometry with limits of quantification of 3.0 pg/mg. All maternal hair specimens were washed with methylene chloride before analysis, and when sufficient amounts of maternal hair were available, specimens also were analyzed without washing. Infant hair specimens were not washed.

Results: Buprenorphine concentrations were significantly greater in unwashed hair than washed hair (P = 0.031). Norbuprenorphine concentrations were significantly greater than buprenorphine concentrations in both maternal (P = 0.0097) and infant hair (P = 0.0033). There were statistically significant associations between the cumulative maternal dose of buprenorphine administered and the concentrations of buprenorphine (washed, P <0.0001; unwashed, P = 0.0004), norbuprenorphine (washed, P <0.0001; unwashed, P = 0.0005), and buprenorphine plus norbuprenorphine (washed, P <0.0001; unwashed, P = 0.0005) for both washed and unwashed maternal hair specimens. There was a significant positive association between concentrations of buprenorphine and norbuprenorphine in maternal hair (washed, P <0.0001; unwashed, P = 0.0003), a trend for this association in infant hair (P = 0.08), and an association between buprenorphine concentrations in maternal unwashed hair and infant hair (P = 0.0002). The buprenorphine:norbuprenorphine ratio increased in distal segments.

Conclusion: Buprenorphine treatment during gestation provides an opportunity for monitoring drug disposition in maternal and fetal tissues under controlled conditions.