Breastfeeding and Medicines Flashcards
what is the first important information about breastfeeding and medicines?
If a mother is taking chronic medication check the information of safety in breastfeeding during the antenatal period.
what is pharmacokinetics?
How the drug is absorbed, transported, metabolised and excreted
what happens once the drug is absorbed?
- Once the drug is absorbed, how does it move into the blood and subsequently into the milk It is important to remember once the baby has consumed the milk, they will also have to absorb, metabolise it before it has an effect
what is important to remember about once babies have consumed milk after mums have taken certain medications?
they will have also absorb, metabolised it before it has an effect.
- The dose will be significantly lower that is secreted through breastmilk than if they were going to get it as a therapeutic dose.
what is a drugs half life?
half life is the time taken for 50% of the drug to leave the system
what happens after 5 half lifes?
After 5 half-lives the amount of drug left in the system is so small that it can be said to have left the system. Therefore, it will have minimal effect to no effect on mum and no effect on baby via breastfeeding.
if a mum is not breastfeeding during the half life time for drugs to leave her system what is important to do?
It is important that if a mum is withholding milk while the drug half lives as in leave the system, that you support the mother with maintaining her milk supply to avoid mastitis.
what is the problem with chronic medication exposure?
The problem comes when a drug is taken every day and the half-life is more than 24 hours, in particular if the baby is under 6 weeks as their liver and kidneys function have not matured.
what is the significance of pethidine?
- A drug you need to be aware of in particular is pethidine.
- These drugs begin to accumulatedue to the amount of drug left in the system when the next dose is taken. This can lead to toxicity.
- Babies exposed to pethidine in the neonatal period may become sleepier and feeding can be affected.
what is the important message 2 about breastfeeding and medicines?
- Try to avoid drugs with long half lives under 24 hours
- Use drugs with high protein binding, ideally >90% (found in hale)
- Choose medications with a milk-plasma ratio <1
- High molecular weight = less passage into milk and less oral bioavailability
Drugs licensed for use in children are ideal and will reach concentrations way below that of treatment dose.
what is steady state concentration?
timing does in relation to feeding. This only works with acute medications e.g. blood pressure meds, pain meds.
- Once a drug has been taken for 5 half-lives it has reached steady state concentration. This means the level of drug is constant across 24 hours.
Therefore, it is not possible to avoid/reduce exposure with long term medication
how does medications transfer into milk?
- In the first few days after birth, drugs can pass freely in to the milk
- This is due to the intracellular gaps being wide open to allow the free transport of immunoglobulins to the baby via the milk.
the intracellular gaps close around day 3 and at this point the drug must pass through the cell membrane which is much more difficult.
- This is due to the intracellular gaps being wide open to allow the free transport of immunoglobulins to the baby via the milk.
what is the rule for therapeutic range?
- As a rule, if it is licensed for use in children, it will be safe in breastfeeding.
Sometimes mother and baby will be taking the same medications e.g., paracetamol. The amount passed to the baby through the milk is low and does not affect the dose the child is taking. Baby can also have paracetamol and ibuprofen when the mum has during breastfeeding also.
what is the importance of the size of the molecule?
- The larger the molecule the less ability to pass into the milk.
Large molecules tend to have low or no oral bioavailability
what is milk-plasma ratio?
- This refers to the concentration of the protein free fraction in the milk and plasma.
- Any ratio over 1 would indicate the drug may have the ability to concentrate in the milk. Other pharmacokinetic factors should be considered in this instance.