Pharmacology

Question 1

Pregnancy effect

Answer 1

Increase GI transit time & absorption
N+V impair absorption
Increase blood volume -> reduce concentration
increase hepatorenal clearance

Question 2

Antiepileptics

Answer 2

HD folic
Avoid change in pregnancy
Lowest effective dose, monotherapy
Baseline level
BF safe

Fetal anticonvulsant syndrome - dysmorphic, devel delay
Common anomaly: NTD, orofacial clefts, cardiac defect
Valproate -> neurodevelopmental delay

Asso. PTB/IUGR
Vit K deficiency in newborn

Parenteral antiepileptics in labour : benzo

Question 3

Anticoags

Answer 3

Warfarin - Vit K antagonist
Teratogenic
BF safe
Monitor w/ INR, reverse with vi K + prothrombinase complex
Monitor IUGR

Fetal warfarin syndrome:
Microcephaly, bradydactyly, nasal hypoplasia, neurodevp delay
Pregnancy - avoid in T1, continue 2 weeks prior to birth replace with LMWH, switch back postpartum

Heparin
Safe, does not cross placenta
LMWH vs heparin
- same effectiveness
- lower HIT, osteoporosis
- single dose
- longer acting

Cons:
- controversial evidence on bleeding risk -> increase post CS haematoma
- longer acting
- renal adjustment
- less reversal w/ protamine sulphate

Question 4

Lithium

Answer 4

Monitor lithium toxicity - N+V, LOC, seizure, arrhythmia, renal failure
TFT/LFT monitoring
Drug level monthly + weekly after 36/40
Intrapartum high toxicity - withhold 1-2 days

Asso. Ebstein anomaly
Neonatal lithium toxicity
NOT safe for BF

Question 5

Immunosuppressants

Answer 5

Prednisolone
- increase PPROM/PTB/GDM
- risk of adrenal insufficiency in labour -> IV hydrocort

Others: monitor GDM/PTB/FGR

Safe:
Azathiaprine, hydroxychloroquine, cyclosporin, tacrolimus
Inflixamab - risk of neonatal immunosuppression

Teratogenic - mycophenalate, cyclophosphamide, methotrexate

Question 6

Cardiac/HTN

Answer 6

ACE/ARB - teratogenic, fetal renal failure
Amiodarone - fetal tachycardia, thyroid disfunction
Loop diuretics - placenta hypoperfusion, otherwise safe
Spironolactone - male fetus ferminisation
Statins - teratogenic

Question 7

Radiation

Answer 7

<50mGy no increase risk - congenital anomaly, ID, FGR, MC
>50mGy - rise childhood cancer from 0.2 to 0.3%

MRI safe - avoid gadolinium (okay in BF)

ALARA
- as low as reasonably achieved -> shortest time, lowest power for desired image
- risk of thermal injury, tissue cavitation
- aim TI <0.7, avoid use of pulse/color doppler