Prescribing in Pregnancy

Question 1

Do most drugs cross placenta?

Answer 1

Yes, except LMW drugs e.g. Heparin

Question 2

What drugs cross more quickly than others?

Answer 2

Small, lipid soluble

Question 3

How is absorption effected in pregnancy?

Answer 3

Morning sickness

Question 4

How is distribution effected in pregnancy?

Answer 4

Volume of distribution increased due to increased PV and fat stores
Decreased protein binding, so increased free drug

Question 5

How is metabolism effected in pregnancy?

Answer 5

Increased liver metabolism of some drugs e.g. phenytoin

Question 6

How is elimination effected in pregnancy?

Answer 6

Elimination of renally excreted drugs increases- increased GFR

Question 7

Are pharmacodynamics effected in pregnancy?

Answer 7

No significant changes- pregnant women can be more sensitive to some drugs e.g. hypotension with antihypertensives in 2T

Question 8

What should be taken pre-conception?

Answer 8

Folic acid 400mcg daily for 3 months prior and first 3 months of pregnancy
Safest drug therapy for existing chronic conditions

Question 9

When is the period of greatest teratogenic risk?

Answer 9

4th to 11th week

Question 10

Describe drug use in 1T?

Answer 10

Avoid drugs if at all possible unless maternal benefit outweighs risk to fetus

Question 11

What teratogenic effects can ACEI/ARBs have?

Answer 11

Renal hypoplasia

Question 12

What teratogenic effects can androgens have?

Answer 12

Virilisation of female fetus

Question 13

What teratogenic effects can antiepileptics have?

Answer 13

Cardiac, facial, limb, neural tube defects

Question 14

What teratogenic effects can cytotoxics have?

Answer 14

Multiple defects, abortion

Question 15

What teratogenic effects can lithium have?

Answer 15

CV defects

Question 16

What teratogenic effects can methotrexate have?

Answer 16

Skeletal defects

Question 17

What teratogenic effects can retinoids?

Answer 17

Ear, CV, skeletal defects

Question 18

What teratogenic effects can warfarin have?

Answer 18

Limb and facial defects

Question 19

What can opiates around term?

Answer 19

Respiratory depression

Question 20

What can warfarin cause around term?

Answer 20

Bleeding

Question 21

What did diethylstilbestrol cause?

Answer 21

Vaginal adenocarcinoma in girls aged 15-20yo whose mothers took drug
Urological malignancy in boys

Question 22

Can untreated epilepsy lead to congenital malformations?

Answer 22

Yes- incidence higher than that of women without epilepsy

Question 23

Why does pregnancy increase seizures in 10% of women?

Answer 23

Non-compliance

Changes in plasma concentrations of drugs: persistent vomiting, increased clearance

Question 24

What are frequent seizures during pregnancy associated with?

Answer 24

Lower verbal IQ
Hypoxia
Bradycardia
Antenatal death
Maternal death

Question 25

Do antiepileptics increase the risk of congenital malformations?

Answer 25

Yes- 20/30% risk if on 4 drugs, monotherapy preferred Avoid valproate, phenytoin (96% won't have major malformations)

Question 26

Are insulin and sulfonylureas safe during pregnancy?

Answer 26

Insulin yes, sulfonylureas no- switch to insulin

Question 27

What does poor diabetic control increase the risk of?

Answer 27

Congenital malformations | IUD

Question 28

Do diabetic requirements change during pregnancy?

Answer 28

Yes

Question 29

What can beta blockers do in late pregnancy?

Answer 29

Inhibit fetal growth

Question 30

How should N & V be treated in pregnancy?

Answer 30

Cyclizine

Question 31

How should UTI be treated in pregnancy?

Answer 31

Nitrofurantoin, cephalexin (3T trimethoprim)

Question 32

How should mild pain be treated in pregnancy?

Answer 32

Paracetamol

Question 33

How should heartburn be treated in pregnancy?

Answer 33

Antacids

Question 34

By how much does pregnancy increase the risk of VTE?

Answer 34

10x

Question 35

What thromboprophylaxis for VTE should be used in pregnancy and by who?

Answer 35

LMWH at delivery and up to 7 days post partum if: | 2 or more RFs e.g. obesity, >35yo, smoking, para >3, previous DVT, Caesarean delivery

Question 36

How should suspected or established DVT or PE be treated?

Answer 36

Therapeutic dose of LMWH | Avoid warfarin in early pregnancy (teratogenic) and late pregnancy (risk of haemorrhage during delivery)

Question 37

What drugs enter breast milk?

Answer 37

Most, especially small or fat soluble drugs

Question 38

How can feeding patterns affect amounts of drugs in breastfeeding?

Answer 38

Foremik- protein rick Hindmilk- higher fat content Longer feeds, higher amounts of fat soluble drugs in milk

Question 39

What drug is actively concentrated in breast milk?

Answer 39

Phenobarbitone- suckling difficulties

Question 40

What can amiodarone cause when passed through breast milk?

Answer 40

Neonatal hypothyroidism

Question 41

What can cytotoxics cause when passed through breast milk?

Answer 41

Bone marrow suppression

Question 42

What can benzodiazepines cause when passed through breast milk?

Answer 42

Drowsiness

Question 43

What can bromocriptine cause when passed through breast milk?

Answer 43

Suppresses lactation

Question 44

Which antibiotic given during pregnancy or in early childhood can cause staining of bones and teeth?

Answer 44

Tetracycline- avoid in children up to 8yo

Question 45

Which antiepileptic drug is particularly associated with cleft lip and palate?

Answer 45

Phenytoin

Question 46

Which antiepileptic drug is particularly associated with neural tube defects such as spina bifida and anencephaly?

Answer 46

Valproate