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Suggestions for Prescribing Medication in Pregnant Women

    When possible:

  • Use medication only if absolutely indicated.
  • Avoid initiating therapy during the first trimester.
  • Select a medication with a proven track record in human pregnancy.
  • Use a single-agent.
  • Use the lowest effective dose.
  • Discourage the use of over-the counter drugs that might interact with prescription medications.

  Modified from:  Norwitz ER, Greenberg JA.Antibiotics in pregnancy: are they safe? Rev Obstet Gynecol. 2009
   Summer;2(3):135-6. PMID: 19826569


Factors that Appear to Determine the Extent of Placental Transfer of Drugs Administered to the Mother [1-5]

  • The molecular weight of the drug; Drugs with molecular weights (MW)  less than 500 D appear to cross the placenta easily, drugs with MW greater than 500  have  incomplete transfer across the human placenta. Drugs with very high MW , such as insulin with a M.W ~ 5800 do not normally cross the placenta.
  • The pKa (pH at which the drug is 50% ionized); Strongly dissociated acid drug molecules should have an incomplete transfer, but this does not seem to be an absolute rule
  • Physiological properties of the placenta (blood flow, gestational age)
  • Expression and activity of metabolizing enzymes and efflux transporters (e.g. ATP-binding cassette (ABC) transporters ). For example placental 11beta-hydroxysteroid dehydrogenase 2 (11beta-HSD2) enzyme inactivates prednisolone by interconversion into
    prednisone , and ABC transporters pump tenofovir disoproxil fumarate  from trophoblast back to maternal circulation.
  • The extent of drug binding to plasma protein does not appear to influence the type of drug transfer across the human placenta to a significant degree.

FDA Use in Pregnancy Ratings  (Obsolete)

Prescription Drugs of Choice During Pregnancy -perinatology.com
      Medications recommended as first line agents during pregnancy by various organizations and authorities .

Over-the Counter Medications of  During Pregnancy


RESOURCES
 
  • Bumps (Best Use of Medicines in Pregnancy)
  • Breastfeeding and Maternal Medication(PDF file)
        World Health Organization, 2002
  • Daily Med Package insert information on prescription drugs.
  • Drugs.com
  • Drugs in Pregnancy and Lactation: A Reference Guide to Fetal and Neonatal Risk Classic text by  Briggs GG, Freeman RK, Yaffe S.J.
  • Drugs, Pregnancy, and Lactation Archive of Ob.Gyn.News articles written by Lee Cohen, Gerald G. Briggs, and Gideon Koren.
  • Drug Safety in Lactation
     Prescriber Update
  • InfantRisk
  • Journal of Antimicrobial Chemotherapy
  • Lactmed
    The LactMed® database contains information on drugs and other chemicals to which breastfeeding mothers may be exposed.
  • MotherToBaby (Organization of Teratology Information Specialists) has compiled "fact sheets" on various exposures of concern.
  • Office of Dietary Supplements
     NIH
  • Pregnancy Drug Registries
  • Prescribing medicines in pregnancy database
    Australia
  • Reprotox
     Fee required
  • RX List Pill Identification Tool

    References

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