Lactation Flashcards
How do drugs move into breast milk
Through passive diffusion
- Only unbound, unionized molecules can cross membrane
Movement of Molecules across Membrane
- Molecular Weight
High molecular weight = Low milk level
Movement of Molecules across Membrane
- Protein Binding
High protein binding = Low milk level
Movement of Molecules across Membrane
- Ionization
Ionized = Low Milk Level
Unionized = High Milk Level
Movement of Molecules across Membrane
- Lipid Solubility
High lipid solubility = High milk level
Movement of Molecules across Membrane
- Acidic Drugs
Mainly ionized in plasma
Movement of Molecules across Membrane
- Basic Drugs
Less ionized in plasma
Movement of Molecules across Membrane
- Bound Drugs
Can not cross membrane
Movement of Molecules across Membrane
- Partitioning Ranking
Highest Partitioning:
- Alkaline, low plasma binding
Lowest Partitioning:
- Acidic, high plasma binding
Risk of Exposure to Infant
Volume of milk a day
Concentration of drug
Amount ingested by infant
Infant’s ability to absorb the drug
Infant’s ability to clear the drug
- Ontogeny of Hepatic function
- Ontogeny of Renal function
Daily Infant Dose
Concentration of drug in milk * volume ingested in 24 hours
- Concentration is obtained from literature
- Volume is variable
Relative Infant Dose
Daily Infant dose (mg/kg/day) / Daily Maternal Dose (mg/kg/day)
- Expressed as a percentage of the mother’s dose
- RID above 10% may be of concern (not based on concrete scientific evidence)
RID Limitations
Does not change even if maternal dose changes
RID value of a specific drug can drift over time
Does not consider pathophysiology, ontogeny, or dynamics of the patient
Does not consider idiosyncratic pharmacological effects
- Non dose dependent differences
Postpartum Depression
Avoid Fluoxetine
- Long half life, stays in the system for a while
Postpartum Pain Control
Codeine/Morphine/Oxycodone
- Avoid use
Opioids if used should be used with caution
- Decrease dose and duration
