Pharmacology treatment during Pregnancy , breastfeeding , neonate

Question 1

Explain changes of pharmacokinetics during pregnancy

Answer 1

Absorption : gastric emptying is delayed for oral preparations ( sitting in stomach for a while might change it’s effect )

Distribution : Total body water and fat are increased = lower concentration of water soluble and lipid soluble drugs AND protein binding is reduced increasing free drug concentration ( active drug )

Metabolism : increased clearance of drugs depending on liver enzyme activity phenytoin and theophylline ( increased liver activity in 3rd trimester )

Elimination : increased renal plasma flow doubles the elimination of renal cleared drugs such as penicillins

Question 2

Do drugs affect the fetus ? what factors contribute to the degree it effects the fetus at ?

Answer 2

• Most drugs cross the placenta but in variable degrees

- Lipid soluble , water soluble , molecular size, protein binding and metabolism affect crossing

Question 3

What are the features of a drug that would most easily cross the placenta

Answer 3

Small , lipid soluble , unbound , uncharged molecule crosses most easily

Question 4

What drugs can effect day 0-16 of gestation

Answer 4

Cytotoxic and Alcohol

Question 5

What drugs will effect fetal development first trimester ( organogenesis stage ) Day 17-60

Answer 5

Most Teratogens

Question 6

What drugs will effect fetal development after 60+ days

Answer 6

Alcohol , Nicotine , Radioactive iodine , Corticosteroids

Question 7

What drugs should be avoided in pregnancy ( Hint : 8 ) , give examples

Answer 7

1- ACEi / ARBs : if patient wants to have a family, not using contraceptive then not prescribed
2- Anticonvulsants ( Phenytoin , valproate, carbamazepine )
3- Antipsychotics ( lithium )
4- Antibiotics ( tetracyclines, trimethoprim , metronidazole )
5- Antithyroid ( iodine , carbimazole, propylthiouracil )
6- Anticoagulant ( warfarin, DOACs )
7- Abuse : alcohol, cigs, opioids,
8- DMARDS / cytotoxics ( methotrexate / cyclophosphamide : reduce high cell turnover

Question 8

What is used instead of ACEi if patient is trying to get pregnant or is pregnant

Answer 8

Labetolol

Question 9

What if thyroid problems start during pregnancy

Answer 9

Small amount of carbimazole can be given , not much because can badly effect fetus.

If person with thyroid problem is planning to get pregnant ideally they should wait until thyroid problems are treated first.

Question 10

When is the administration of drugs at the greatest risk during a pregnancy

Answer 10

In the First Trimester

Question 11

What is Phocomelia

Answer 11

Phocomelia is the malformation of limbs

Question 12

What is thalidomide

Answer 12

Thalidomide was used for first trimester vomiting for anti-sickness. This caused Phocomelia in Infants

Question 13

What is the treatment for nausea and vomiting ( morning sickness ) in pregnancy

Answer 13

1- If mild : nothing or vitamin/electrolyte support
2- 1st line : Promethazine, cyclizing ( antihistamine ) , prochlorperazine & reassess after 24 hours and switch between drugs if not working
3- 2nd line : metoclopamide or ondansetron ( for less than 5 days )
4- 3rd line : Methylprednisolone ( high dose IV corticosteroid ) only in severe cases

Question 14

What is the treatment of asthma in pregnancy

Answer 14

1- maintain with inhalers

2- Prednisolone if needed

Question 15

What is the treatment for hypertension in pregnancy

Answer 15

1- Labetolol
2- Nifedipine ( B blocker )
3- Methyldopa

Question 16

What is the side effect of Methyldopa

Answer 16

works in brain so may change mood of mother

Question 17

What antibiotics are used during pregnancy for UTI

Answer 17

1- 1ST LINE : Nitrofurantoin

2- 2nd line: Amoxicillin , Cefalexin

Question 18

What anticoagulation medications are safe during pregnancy

Answer 18

Heparin and LMWH. Avoid Warfarin and DOACs

Question 19

What anticonvulsants are safe during pregnancy

Answer 19

Seizures are more of a risk than the drug , must consult specialist ( neurologist & OB )

Question 20

What drugs should be avoided while nursing

Answer 20

1- Diazepam 
2- Alcohol 
3- Lithium 
4- Iodine / propythiouracil 
5- Opioids ( if on them mother advised to not breast feed ) 
6- Tetracyclines 
7- Corticosteroids

Question 21

How can you give a drug while a mother is Breastfeeding

Answer 21

If drug can affect baby try to give drugs in timing where it doesn’t affect the breast milk

Question 22

Explain changes in Pharmacokinetics of Baby

Answer 22

Absorption :
1- surface area / bodyweight is greater so absorption of topical agents is increased
2- intramuscular absorption is impaired due to reduced mass
3- rectal absorption is relatively efficient

Distribution:
Body water % is higher so loading dose is greater for drugs based on body weight.
Albumin binding decreased so free concentrations of highly bound drugs increase.

Metabolism:
Impaired oxidation increases concentration of drugs like warfarin, diazepam.
Impaired glucuronidation increases risk of toxicity to drugs metabolized by this mechanism (chloramphenicol )

Elimination :
GFR and reabsorption is impaired so dose reduction needed for renal cleared drugs ( ahminoglycosides, digoxin, penicillin ) . By 6 months renal function is normal and standard doses could be used.

Question 23

Why can you get neonatal jaundice

Answer 23

If you give highly binding drugs to babies they can displace bilirubin from its protein binding

Question 24

What is grey baby syndrome

Answer 24

When Chloramphenicol is given to babies

Question 25

What inherited conditions should you take caution that you don’t know if a neonate has when prescribing

Answer 25

1- Oxidation / acetylation rate : slow or toxic response / fast failed response to standard dose
2- Glucose 6 phosphate dehydrogenase deficiency : can develop hemolysis
3- pseudocholinesterase deficiency : apnoea after neuromuscular blockade

Question 26

What are the rules for prescribing to neonates

Answer 26

1- base dosage on estimated body surface
2- use paediatric formulary
3- special adjustments for neonates that are premature
4- avoid new drugs
5- adverse effects will be different than adult