These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: A comparison of morphine and methadone disposition in the maternal-fetal unit.
    Author: Szeto HH, Umans JG, McFarland J.
    Journal: Am J Obstet Gynecol; 1982 Jul 15; 143(6):700-6. PubMed ID: 7091244.
    Abstract:
    The extent of fetal exposure to a drug is a function of placental and fetal clearances of the drug. We have compared the placental and fetal clearances of morphine and methadone under steady-state conditions in the chronic pregnant ewe preparation. Morphine and methadone were infused at constant rates to the mother and fetus, and steady-state maternal and fetal plasma concentrations of the drugs were determined by radioimmunoassay. At steady state after maternal infusion of the drugs, the maternal: fetal free drug concentration ratios were 7.6 +/- 0.6 for morphine and 2.9 +/- 0.6 for methadone. The clearance of morphine from mother to fetus (24.9 +/- 3.0 ml/min) was fifteenfold less than that of methadone (390.3 +/- 92.8 ml/min). Fetal nonplacental clearance of methadone (381 +/- 89.1 ml/min) was higher than that of morphine (125.6 +/- 15.3 ml/min). Fetal clearance accounted for 67.4 +/- 3.9% of total morphine clearance from the fetal compartment, but only 42.8 +/- 4.9% of total methadone clearance. Fetal clearance of methadone increases with age in the early third trimester. The lower extent of fetal exposure to morphine compared to methadone is due primarily to a slower clearance of morphine across the placenta from mother to fetus rather than a more rapid clearance of morphine by the fetus.
    [Abstract] [Full Text] [Related] [New Search]