Medications and breastfeeding 4 Flashcards
1
Q
What are the benefits of breastfeeding for mothers?
A
- assist in losing weight
- reduces risk of T2DM, blood pressure and heart disease
- lowers rates of breast and ovarian cancer
- promote bonding, its convenient and free
2
Q
What are the benefits of breastfeeding for baby?
A
- all nutritional requirements for growth & development
- breast milk is easier to digest
- contains antibodies and immunoglobulins
- reduces risk of infectious diseases
- reduces risk of SIDS
3
Q
Is medication through breastmilk a danger?
A
- most medications transfer into milk
- however, the amount received by breastfed infant is LOW
- very few pose significant risk
4
Q
What are some adverse drug rxn reports in infants from medication in breast milk?
A
- opioids 25%
- antidepressants 15%
- multiple drug classes 11%
- anticonvulsants 11%
- iodine 6%
- antimicrobials 6%
- antipsychotics 4%
- cardiovascular drugs 4%
- sedatives 4%
5
Q
What are the aims in treating a breastfeesding mother?
A
- treat mother effectively
- minimse infant exposure
- minimally disrupt nursing
- withholding breastfeeding is not a RISK FREE option as mother and baby will be DEPRIVED of benefits
6
Q
How do drugs transfer into milk?
A
- mainly by passive diffusion
- in the early days following delivery there are large gaps inbetween the alveolar cells in the breast tissue and that allows the passage of immunoglobins and maternal proteins
- because theres a small amount of breast milk being transferred at this time its not a concern in terms of medication
- over the first
7
Q
How does the drug get into the milk and how is it cleared from the milk?
A
- once drug is in the system, it goes into the maternal plasma and then transferred across into the breast milk
- once its in the plasma, mum starts to clear it through renal and hepatic systems
- the drug that goes from the maternal plasma to the breast milk is a two way process
- once the maternal plasma concentration is dropping through clearance, the drug comes back out of the breast milk
- the drug doesnt just go into the breast milk and sit there, once mum is metabolising the drug, it does actually come out as a concentration gradient
- in the breast milk, the baby will ingest the drug and it will also clear the drug
8
Q
What are the 3 factors that effect infant exposure to the drug?
A
- drug properties
- maternal factors
- infant factors
9
Q
- Drug properties
A
- protein binding
- if a drug is highly bound (>90%)–> very difficult to diffuse into breastmilk
- ibuprofen, warfarin
- molecular weight
- if a drug is quite small (<200daltons)–> likely to cross readily into breastmilk
- between 800-1000 daltons–> might cross
- >1000daltons–> unlikely to cross
- lipid solubility
- milk is more lipophilic and crosses more easily
- drugs will cross more easily if they’re lipophilic
- e.g. benzodiazepines
- volume of distribution
- if VOD is high this means the drug is distibuted in high concentrations in remote parts of the body & may not stay in the blood for long therefore may not cross into the breastmilk
- the higher the VOD, the less likely the drug is going to cross into the breast milk
- ionisation
- pKa measures pH at which drug is equally ionic and non ionic
- the more ionic a drug, the less it can transfer from milk to the plasma, so pKa>7.2 can be ion trapped in milk
10
Q
- Maternal factors
A
- pharmacogenomics
- influenced by metabolism differences
- e.g. codeine- each person will have a different rate of metabolising codeine
- ultrametabolisers of codeine-morphine; are at greater risk of concentrations of morphine being high in the breast milk
- maternal bioavailability
- if a drug has low bioavailability, it has low plasma levels and therefore low concentrations in the breast milk
- e.g. pyrantel, <10% absorbed through the gut
- maternal plasma concentration
- drug in high plasma concentration, more likely to cross into breastmilk
- via passive diffusion
11
Q
- Infant factors
A
- amount of drug ingested by infant
- dependent on milk concentration and daily milk intake
- ~150mL/kg/day
- if we know the milk conc we can determine how much of the drug the baby is exposed to
- oral bioavailability in infant
- infants stomach acidity denatures many drugs
- if small amt of drug which is not orallly bioavailable present in the breastmilk, baby wont absorb any
- age of infant
- the younger the baby, the more likely there is for an adverse effect
- pre term infants have immature metabolism
- use in infants
- if used therapeutically unlikely to be toxic via breastmilk
12
Q
How is infant exposure interpreted?
A
13
Q
How do we assess the risk to the infant?
A
- infant
- age- premature and newborn at greater risk
- size- calculate dose
- stability- unstable infants may increase risk
- drug
- paediatric use
- inherent toxicity
- dose based on milk transfer
- what is the relative infant dose? (RID)
- infant dose- compare this to therapeutic use
- milk/ plasma ratio
14
Q
What is a safe dose?
A
- relative infant dose (RID) <10%
- lower dose if infant preterm or in first month of life
- less if drug is inherently toxic
- less where doses are uncontrolled- prn dosage
- check literature for reports of adverse effects
15
Q
How do we minimse drug exposure?
A
- withhold drug
- delay treatment
- consider alternative routes of administration
- use lowest appropriate dose
- select drug within class having lowest RID
- avoid nursing when milk concentraton is high
- withhold feeding temporarily for short time
- discontinue feeding
