Meds Flashcards
How easily does medication pass from plasma to milk in the first week of lactation?
Very easily as the spaces between lactocytes are wide spread allowing meds to easily transfer to milk. However, since baby is only taking small volumes of milk there may not be much concern for transfer to baby
Drugs transfer into human milk if they are…
- Highly lipid soluble
- Attain high concentrations in maternal plasma
- Have a LOW molecular weight (<500)
- Are low protein binding
- Easily pass into the brain
How do drugs enter the maternal milk compartment?
Primarily through passive diffusion
What is the most important determining factor of drug penetration into mothers milk?
The mothers plasma level.
What is ion trapping in milk?
Due to lower pH of human milk (7.0-7.2) the ionic state of the drug changes and prevents its exit back into maternal circulation ( barbiturates and iodides)
Warfarin, has a high maternal protein binding capacity. Would this medication be a risk for the infant?
NO. A high protein binding capacity allows milk to bind to plasma albumin and will stay in plasma circulation.
What is bio availability?
The amount of drug absorbed from the gut into the blood stream
What is the percentage of relative infant dose ( RID) that is considered safe for infants
An RID <10%
Why would you recommend a Dr recommend a drug with a shorter half life?
Drugs with shorter half lives peak rapidly and then are eliminated form the maternal plasma- less exposure time to milk compartment. Urge mom not to breastfeed while e drug is at its peak level.
Name 4 examples of medications that have a long half life and can build up in the infants plasma over time
- Barbiturates
- Benzodiazepines (tranquilizers ie. valium)
- Meperidine (demerol)
- Fluoxetine (prozac) (half life 216 hours)
If you had a choice would you recommend drugs with a higher or lower protein binding capacity?
Higher. they are bound to the mothers plasma and not as easily transferred to the milk compartment
Drugs move in and out of breast milk through passive diffusion – high to low- and with time may shift back the other way. Give an example
Alcohol ( half life– 24 min)
Which medications those with a high molecular weight or a low molecular weight are a better choice for the breastfeeding mother.
High molecular wt limits movement into breast milk.
MW >500 does NOT transfer
Insulin MW> 6,000
Heparin MW 40,000
A good definition of good protein binding would be at what percentage?
90%. Propranolol 90%
Lithium 0% (low protein binding and a poor choice)
True or false drugs that are active in the central nervous system usually have a low lipid solubility.
FALSE. The have high lipid solubility and therefore penetrate into breastmilk in higher concentration
