Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2005 Feb;192(2):633-9.
doi: 10.1016/j.ajog.2004.08.030.

Temporal changes in drug metabolism (CYP1A2, CYP2D6 and CYP3A Activity) during pregnancy

Timothy S Tracy  1 , Raman Venkataramanan, Douglas D Glover, Steve N Caritis; National Institute for Child Health and Human Development Network of Maternal-Fetal-Medicine Units
Affiliations

Temporal changes in drug metabolism (CYP1A2, CYP2D6 and CYP3A Activity) during pregnancy

Timothy S Tracy et al. Am J Obstet Gynecol. 2005 Feb.

Abstract

Objective: The purpose of this study was to determine whether drug metabolism (CYP1A2, CYP2D6 and CYP3A) activity varies in the pregnant state compared with the nonpregnant state.

Study design: Subjects were studied at 14 to18 weeks of gestation, 24 to 28 weeks of gestation, and 36 to 40 weeks of gestation and again at 6 to 8 weeks after the delivery. Twenty-five subjects completed all 4 study periods and had evaluable data. Salivary caffeine clearance was used as a measure of CYP1A2 activity; dextromethorphan O- and N-demethylation were used to assess CYP2D6 and CYP3A activity, respectively.

Results: CYP1A2 activity was significantly reduced at all periods of the pregnancy as compared with the postpartum period during the first (-32.8% +/- 22.8%), second (-48.1% +/- 27%), and third periods (-65.2% +/- 15.3%), respectively. In contrast, CYP2D6 activity was increased significantly throughout the pregnancy (25.6% +/- 58.3% at 14-18 weeks of gestation, 34.8% +/- 41.4% at 24-28 weeks of gestation, and 47.8% +/- 24.7% at 36-40 weeks of gestation) as compared with the postpartum period. CYP3A activity was consistently, significantly increased (35%-38%) during all stages of the pregnancy.

Conclusion: Opposing changes in drug metabolism occur during pregnancy, with CYP1A2 activity decreased and CYP2D6 and CYP3A activities increased. The direction of dosing adjustments during pregnancy will depend on the drug and the enzyme that is responsible for its metabolism.

PubMed Disclaimer

Publication types