Lactation Pharmacology Flashcards
Why is drug transfer to milk enhanced in the first 4 days postpartum?
large gaps between alveolar cells permit drug passage (after this point, alveolar cells enlarge and shut off the gaps)
Drugs that act on which system generally pass more easily into milk?
CNS drugs (lipid soluble)
Main method by which drugs enter the milk?
Diffusion (plasma-milk)
Drugs with high protein binding enter milk freely. True or false
False. They are largely sequestered in the protein and have a hard time entering the milk.
Drugs above which molecular weight do not readily enter the milk?
800 Daltons
What is ion-trapping?
Drugs with a pKa higher than 7.2 may get trapped in the milk compartment and unable to exit. It is rarely clinically important
The lower the bioavailability of a drug, the _____ transfers into the breastmilk. We prefer drugs with a _____ bioavailability.
less, lower.
The highest risk for drug accumulation in the infant is when?
first two months after birth
Drugs with high milk-to-plasma ratio enter the milk easily. True or False
True
Medication with high milk to plasma ratio is never safe for breastfeeding. True or false
false. A high milk to plasma ratio but a low parental serum lever still ends up being a relatively low infant dose.
Most important clinical parameter for determining safety of a drug entering the milk
Relative infant dose
Calculation for RID
infant dose mg/kg/day divided by parent dose mg/kg/day
More caution is required at which age? why?
2 weeks-6 months, because milk volume is high and infant ability to metabolize drugs is low
At which age are infants more capable of metabolizing small loads of drugs through milk?
9-12 months
One strategy for lowering infant dose with timing of feeds/medication spacing?
breastfeed, then take medication and avoid feeding at peak plasma level. (works for drugs with half life less than 4 hours)
Are hair dyes and topical creams safe for breastfeeding infants?
Yes
What is the parental plasma level of inhaled (asthma) medications?
Virtually nil
Can milk be save/stored or fed to an infant if breastfeeding parent is using anticancer, antimetabolite or other noxious drugs?
No. they must follow guidelines for pumping and discarding milk for 5-7 half lives
Is it safe to breastfeed if undergoing CT/MRT with contrast?
Generally speaking, yes
List some common drugs used during lactation which are considered safe
Acetaminophen, Aspirin, Ibuprofen, Diphenhydramine, Cetirizine, vaccines
What is one vaccine not recommended during lactation?
Yellow fever (when infant is less than 9 months old)
Review antibiotic usage
- Tetracyclines: (safe short term)
- acyclovir: (HSV treatment, safe)
- penicillins: safe
- cephalosporins: no concerns
- fluroquinolones: (prefer ofloxacin but probably fine)
- metronidazole: moderate RID but nontoxic so used clinically
- antifungals: avoid clotrimazole
General consensus on antidepressant therapy?
Strongly recommended for parental depression. Most often studied class of drugs in lactation. Minimal transfer to milk. Most often used SSRIs
Which anticoagulants are preferred over Direct Oral Anticoagulants?
Enoxaparin, warfarin
