2. Advice on infant feeding
• Breast milk is the best form of nutrition for infants.
• Exclusive breastfeeding for the first 6 months.
• Breastfeeding (and/or formula milk) with appropriate solid food after 6 months, ideally for
up to 1 year.

4. Medication and breastfeeding
• Breast-feeding has many benefits.
• Potential harm to the nursing infant from maternal drugs is a reason to discontinue breast-
feeding.
• Physicians receive little education about breast-feeding and even less training on the effects
of maternal drugs on the nursing infant.

6. :

7. Methods of drug transfer into milk
• Passive diffusion
• Active transport against a concentration gradient
• Transcellular diffusion

8. • Diffusion
– Plasma levels in the mother
– Lipid solubility of the drug and fat content of milk
– Milk ph
– Molecular size of the drug
– Protein binding of the drug in mother’s plasma
– Maternal half-life of the drug
– Molecular weight of drug
– Bioavailability of the medication to the infant

9. Transfer of dugs into Breast Milk
• Nearly all drugs transfer into breast milk to some extent.
• Notable exceptions are heparin and insulin {too large to cross biological membranes}.
• Drug transfer from maternal plasma to milk is, with rare exceptions, by passive diffusion
across biological membranes.
• Almost all medication appears in small amounts, usually less than 1% of the maternal dose
• Very few drugs are contraindicated for nursing mothers

10. • Transfer of drug into Breast Milk
• The amount of breast milk consumed by the infant.
• The pharmacologic activity of the drug: absorption, distribution, metabolism and elimination
by the infant.
• Condition of the infant:
• Greater precaution for infants
– premature or
– compromised or
– in the first week of life than for older, healthy infants.

13. Drug therapy during lactation
• Drugs that passes minimally into milk:
– Acid drug
– Highly protein bound drug
– E.g NSAID
– Weekly basic drug with low plasma
protein binding and highly lipophilic
will achieve higher concentration in
milk
– E.g. sotalol.

14. Factors affecting drug transfer
• The maternal serum drug concentration.
• Drugs:
– pKa of drug (fraction of drug that is ionized at a given pH)
• Basic drugs -> ionized at acidic pH(low pH) -> trapped in milk
• Acidic drug ionized at higher pH -> trapped in maternal plasma
– Protein binding (highly protein bound drug -> less transfer to milk)
– Lipipophilicity: (high lipophilic drugs-> more drug in milk).
– Molecular weight of drug: high MW -> less drug in milk (insulin, heparin do not enter
breast milk)

15. Factors determining drug concentration in milk
• Milk composition
– Milk at the end of a feed (hindmilk) contains considerably more fat than foremilk and
may concentrate fat-soluble drugs.
• Age of infant:
• In the early postpartum period, large gaps between the mammary alveolar cells allow
many dugs to pass. These gaps close by the 2nd week of lactation.
• Premature babies & infants less than 1 month have a different capacity to absorb and
excrete drugs than older infants.
• Nursing time of baby.
• Milk to plasma concentration(M/P) ratio: for most drug M/P ratio is <1 (drugs with higher
M/P ratio (e.g. 5) are unsafe)

16. Estimating risk to infant
• Milk to plasma concentration (M/P) ratio:
• If M/P ratio of a drug is known
• Amount (dose) of drug ingested by infant can be calculated by
• Dinfant = Cpmat x M/P x Vmax
• Cpmat: average maternal plasma concentration
• Vmax: volume of milk which is assumed to be 150ml
• For most drug, an exposure <10% of weight adjusted maternal dose is acceptable.

17. Calculation of infant exposure to drugs
• The infant dose (mg/kg)
– D infant (mg/kg/day)= C maternal (mg/L) x M/PAUC x V infant (L/kg/day)
Cmaternal= maternal plasma concentration
M/PAUC ratio = milk to plasma concentration ratio area under curve.
Vinfant= volume of milk ingested
• As a percentage of the maternal dose (mg/kg). The volume of milk ingested by infants is
commonly estimated as 0.15 L/kg/day.
An arbitrary cut-off of 10% has been selected as a guide to the safe use of drugs during
lactation.

18. How much of the medicine reaches the baby?
Depends on:
• Blood level of medicine in the mother.
• Characteristics of the medicine.
• Amount of medicine passed into breast milk.
• Amount of milk taken by baby per feed (approx 150mL/kg).

19. Methods of decreasing toxicity in nursing infant
• Select safe drug
• Nurse immediately before taking drug.
• Take drug 3-4 hours before next feeding
• Avoid feeding when drug reaches peak concentration in milk and plasma
• Use drug with short half life
• Instruct patient to monitor ADRs

20. General advice
• Avoid unnecessary use of medicines.
• Assess risk / benefit for mother and baby.
• Higher risk for premature babies.
• Check if medicine licensed for babies.
• Avoid long-acting medicines
• Avoid new medicines.
• Try to time feed to avoid when drug levels in milk are highest.
• Monitor baby for adverse effects.

21. Essential questions to ask
• Has mum already taken the medicine(s) or is she wanting to take?
• Medicine(s), indication, dose, frequency, route & duration of exposure?
• Has this been prescribed or self-treating?
• Have any other medicines been considered or tried?
• What age is the baby? Full term & healthy?
• How often is baby feeding? – Totally breast fed or bottle too?

22. WHO classification of drugs during breastfeeding (2002)
• 1. Compatible with breastfeeding
• 2. Compatible with breastfeeding {occasional mild side effects} Monitor infant for side
effects
• 3. Avoid if possible. {significant side effects} Monitor infant for side-effects
• 4. Avoid if possible. {May inhibit lactation}. Monitor for amount of milk
• 5. Contraindicated {dangerous side effects}

23. Compatible with breastfeeding
• There are no known or theoretical contraindications for their use, and it is considered safe for
the mother to take the drug and continue to breastfeed.

24. Compatible with breastfeeding {Occasional mild side-effects}
Monitor infant for side-effects
• If side-effects:
– stop the drug, and
– find an alternative.
• If the mother cannot stop the drug, she may need to stop breastfeeding and feed her baby
artificially until her treatment is completed.

25. Avoid if possible {significant side effects}
Monitor infant for side-effect

26. Avoid if possible {May inhibit lactation}
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27. Contraindicated {Dangerous side-effects}.
• If they are essential:
• stop breast feeding until treatment is completed.
• If treatment is prolonged, she may need to stop breastfeeding altogether.
• There are very few drugs in this category apart from anticancer drugs and radioactive
substances.

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31. DRUG CLASSIFICATION BY AAP
• Cytotoxic drugs
• Drugs of abuse for which adverse effects on the infant
• Radioactive compounds that require temporary cessation of breastfeeding
• Drugs for which the effect on nursing infants in unknown but may be concern
• Drugs that have been associated with significant effects on some nursing infants and should
be given to nursing mothers with caution
• Maternal medication usually compatible with breastfeeding

33. Before prescribing drugs to lactating women
• Is drug really necessary? If drugs are required, consultation between the pediatrician and the
mother’s physician can be most useful in determining what options to choose.
• The safest drug should be chosen e.g. acetaminophen rather than aspirin for analgesia.
• If there is a possibility that a drug may present a risk to the infant, consideration should be
given to measurement of blood concentrations in the nursing infant.
• Drug exposure to the nursing infant may be minimized

34. • Choose medications with the shortest half-life and highest protein-binding ability.
• Choose medications that are well-studied in infants.
• Choose medications with the poorest oral absorption.
• Choose medications with the lowest lipid solubility.

35. Medication dosing
• Administer single daily-dose drugs just before the longest sleep interval for the infant, usually
after the bed-time feeding.
• Breast-feed infant immediately before medication dose when multiple daily doses are needed

36. Common drugs excreted in breast milk
• Most antibiotics taken by nursing mothers can be detected in breast milk
• Tetracycline concentrations in breast milk is 70% of maternal serum concentrations and
present a risk of permanent tooth staining in infant
• Isonized rapidly reaches equilibrium between breast milk and maternal blood. So that signs of
pyridoxine deficiency may occur in the infant if the mother is not given pyridoxine
supplements.
• Most sedatives and hypnotics enters breast milk sufficient to produce a pharmacologic effect
in infants.
• Barbiturates taken in hypnotic doses by mother can produce lethargy, sedation, and poor suck
reflexes in infant.

37. • Chloral hydrate can produce sedation if infant is fed at peak milk concentrations.
• Diazepam can have a sedative effect on the nursing infant
• Lithium enters breast milk in concentrations equal to those in maternal serum
• Radioiodine can cause thyroid suppression
• Breast-feeding is contraindicated after large doses of radioiodine and should be withheld for
days to weeks after small doses.

38. • Breast-feeding should be avoided in mothers receiving cancer chemotherapy
• Opioids such as heroin, methadone, and morphine enter breast milk (neonatal narcotic
dependence).
• Very small amounts of caffeine are excreted in the breast milk of coffee-drinking mothers.

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