This document discusses drug excretion in breast milk and factors that influence it. Drugs can pass into breast milk through diffusion and be harmful to infants, though the amounts are often small. Basic drugs and those that are less protein-bound tend to concentrate more in milk. Many drugs are safe if taken after breastfeeding, while others like anti-cancer drugs, radioisotopes, and certain antibiotics are contraindicated due to potential harm. The document also outlines pharmacokinetic measures like bioavailability, volume of distribution, half-life, and clearance rate.

1. Drug Excretion

2. Drug excretion in Milk.
• Most of the drugs consumed during lactation
are found to be detected in breast milk
• However ,quantitatively insignificant from
mothers point of view but often sufficient
enough to cause harmful effect on suckling
infant, because of inherent toxicity of the
drug.
• The passage of drug to breast milk is by
diffusion

3. Excretion in milk continued…..
• Drugs which are highly protein bound are less
secreted in milk.
• Milk is slightly Acidic
• Hence basic drugs tend to get concentrated more
in milk than acidic drugs.
• Most drugs are safe, some drugs may suppress
lactation or alter the taste.
• Any drugs to be taken should be done,
immediately after breast feeding or 4 hours
before breast feeding-ensuring that drug gets
cleared.

4. Drugs contraindicated during
lactation.
• Most of Anti-cancer drugs
• All radio-pharmaceuticals, including radio active
isotopes
• Anti-thyroid drugs including radio active iodine.
• Antimicrobial drugs like
1. Tetracyclines –bone and teeth malformations.
2. Chloramphenicol-grey baby syndrome.
3. Sulfonamides-kernicterus.
4. Quinolones- joint and cartilage damage.
5. INH- Hepatotoxicity.

5. Drugs contraindicated during lactation
• Hormones
1. Glucocorticoids –supression of body growth
and HPA axis.
2. Contraceptives –supress lactation.
• CNS depressants/sedative hypnotics-induces
sedation, impaired intellectual development,
delayed milestones
• Opoids analgesic –respiratory depression
• Lithium-cardiac arrythmia and supression of
thyroid function.
• Anthracene purgatives-induce abdomonal
cramps
• Anti psychotic

6. Drugs contraindicated during lactation
• Ephedrine and theophylline - CNS stimulants,
makes child irritable.
• Aspirin – causes Reye s syndrome.
• Among antimicrobials ,penicillin and
cephalosporins are virtually harmless thogh
safe produce abdominal distension and
diarrhoea.
• Bromocriptine and other ergot alkaloids used
deliberately to supress lactation.

7. Drugs excretion through body
integuments like skin ,hair ,nails.
• Some drugs may get deposited in body
integuments.
• When superficial layers are insensibly lost
,which result in drug excretion.
• Presence of drugs in the above is of
importance in arsenic or mercury poisoning
• Quantitatively insignificant but has medico
legal siginificance.

8. Pharmacokinetic convention/measures
/parameters.
1. Bioavaliability
2. Volume of distribution
3. Half-life
4. Clearance rate

9. Half life
• Is defined as the time required for 50% decline
in either concentration or effect of drug.
• Depending upon the ccriteria considered
there are 4 types
1. Plasma half life
2. Biological/elimination
3. Pharmacological
4. physical

10. 1. Plasma half life
• Time required for 50% reduction in plasma
concentration of the drug
• Once peak concentration is achieved, there is
progressive decrease in plasma concentration
of drug
• This is due to drug distribution and disposal
• Plasma concentration decrese in two distinct
phase
• Initial phase of rapid decline-due to
distribution
• Subsequent phase of steady decline –disposal.