Pregnancy Flashcards
What is a critical factor affecting placental drug transfer?
The physicochemical properties of the drug
Other factors include the rate of drug crossing the placenta, duration of exposure, distribution in fetal tissues, stage of development, and combination effects.
What type of drugs tend to cross the placenta readily?
Lipophilic drugs
Example: thiopental.
Which type of drugs cross the placenta slowly and achieve low concentrations in the fetus?
Highly ionized drugs
Example: succinylcholine and tubocurarine.
What is the molecular weight range for drugs that can cross the placenta easily?
250–500
Drugs with higher molecular weights cross the placenta with more difficulty.
What is the role of placental transporters?
They can carry larger molecules to the fetus
Example: maternal antibodies may cause fetal morbidity.
What does a high degree of protein binding indicate for drug transfer?
It may impede transfer for poorly lipid-soluble and ionized drugs
Drugs like sulfonamides and phenytoin show differential binding.
What role does the placenta play in drug metabolism?
It acts as a semipermeable barrier and metabolizes some drugs
Metabolic reactions can lead to toxic metabolites.
What is a potential adverse effect of chronic opioid use during pregnancy?
Neonatal withdrawal syndrome
This can lead to dependence in the fetus.
What is the teratogenic effect of thalidomide?
It can cause phocomelia during critical development weeks
The risk is highest during the fourth to seventh weeks of gestation.
What is a teratogen?
A substance that causes malformations during fetal development
It must cause characteristic malformations and show dose-dependent incidence.
What does Category A indicate regarding drug safety in pregnancy?
No risk to the fetus in the first trimester
Example drugs: levothyroxine, folic acid.
What are the implications of Category D drugs?
Positive evidence of human fetal risk, but potential benefits may warrant use
Example: losartan.
What should nursing mothers do when taking medications?
Take medication 30–60 minutes after nursing and 3–4 hours before the next feeding
This minimizes drug concentration in breast milk.
What is a risk associated with tetracycline use during lactation?
Permanent tooth staining in the infant
Tetracycline concentrations in breast milk can be high.
What can excessive alcohol consumption by a nursing mother cause?
Alcohol effects in the infant
Minimal use has not been reported to harm.
Which drugs are contraindicated in breastfeeding?
Cancer chemotherapy agents and cytotoxic agents
These can harm the infant significantly.
What is the effect of lithium in breast milk?
Enters breast milk in concentrations equal to maternal serum
This can expose the infant to large amounts of the drug.
What is the effect of folic acid supplementation during pregnancy?
Reduces the incidence of neural tube defects
Example: spina bifida.
What is the significance of the New Pregnancy and Lactation Labeling Rule?
Introduced new categorization and labeling for drugs in pregnancy
Implemented in 2015.
What is the primary route of elimination for lithium?
Renal elimination
Clearance of lithium is almost completely dependent upon the kidneys.
What risk may infants face if their mothers are receiving lithium?
Exposure to relatively large amounts of the drug
This can occur through breast milk.
What can iodinated 125I albumin and radioiodine cause in infants?
Thyroid suppression
They may increase the risk of subsequent thyroid cancer as much as tenfold.
Should breast-feeding be avoided for mothers on cancer chemotherapy?
Yes
It should also be avoided for those treated with cytotoxic or immunomodulating agents for conditions like lupus erythematosus.
What is one method to minimize drug effects during breastfeeding?
Pump and discard milk
This is particularly useful for short-term drug use.
What type of drugs should mothers choose to minimize effects during breastfeeding?
Drugs with short half-lives
This helps reduce the amount of drug present in breast milk.
When should drugs be administered to minimize effects during breastfeeding?
Immediately after a feeding or before a long sleep
Timing can help minimize infant exposure.
What should be considered regarding the drug before administration during breastfeeding?
Whether it could be given to neonates
This consideration is crucial for safety.
What factors should be considered about the infant when minimizing drug effects?
Age and health status of the infant
These factors influence the risk of adverse effects.
