title: Transfer of methadone across the dually perfused preterm human placental lobule.
abstract: OBJECTIVE
  The objective of the study was to determine the effect of gestational age and P-glycoprotein expression on transplacental transfer of methadone.
  
  
  METHODS
  Dual perfusion of placental lobule was utilized. Methadone (200 ng/mL) and its [3H]-isotope were cotransfused from the maternal-to-fetal circuit with the marker compound antipyrine (20 microg/mL) and its [14C]-isotope. Concentration of the drugs in trophoblast tissue and both circuits was determined by liquid scintillation spectrometry.
  
  
  RESULTS
  Fetal transfer rate of methadone in preterm placentas was 19 +/- 5.8%, and in term placentas it was 31 +/- 9.7% (P < .01). Clearance index of methadone in preterm placentas (0.57 +/- 0.2) was lower than in term placentas (0.95 +/- 0.3, P < .01). P-glycoprotein expression was higher in preterm than term placentas.
  
  
  CONCLUSIONS
  The ex vivo transfer of methadone across preterm placentas is 30% lower than in term placentas.
authors.affiliation: Department of Obstetrics and Gynecology, University of Texas Medical Branch, Galveston, TX 77555-0587, USA.
authors.forename: Tatiana N
authors.initials: TN
authors.lastname: Nanovskaya
authors.forename: Ilona A
authors.initials: IA
authors.lastname: Nekhayeva
authors.forename: Gary D V
authors.initials: GD
authors.lastname: Hankins
authors.forename: Mahmoud S
authors.initials: MS
authors.lastname: Ahmed
mesh_terms: D005260:Female; D005865:Gestational Age; D006801:Humans; D008431:Maternal-Fetal Exchange / Q000187:drug effects*; D008691:Methadone / Q000494:pharmacology*; D009924:Organ Culture Techniques; D010477:Perfusion / Q000379:methods; D010920:Placenta / Q000187:drug effects* / Q000378:metabolism; D021041:Placental Circulation / Q000187:drug effects*; D011247:Pregnancy; D047928:Premature Birth; D011336:Probability; D012016:Reference Values; D012307:Risk Factors; D012680:Sensitivity and Specificity; D047929:Term Birth
chemical_list: D008691:Methadone