Pharmacology

Question 1

Labetalol

Answer 1

ANTIHYPERTENSIVE

Mechanism of action:
Alpha and beta adrenergic blocker
(non selective)
Competitively blocks beta receptors in heart, peripheral vasculature, bronchi, pancreas, uterus, kidney, brain and liver

Dosing:

Side effects:

Contra-indications:
- Severe asthma

Question 2

Nifedipine

Answer 2

ANTIHYPERTENSIVE

Mechanism of action:
Calcium channel blocker
Block inward current of calcium into cells in vascular smooth muscle, myocardium and cardiac conducting system via L-type calcium channels

Side effects:

Contra-indications:

Question 3

Methyldopa

Answer 3

ANTIHYPERTENSIVE

Mechanism of action:
Centrally acting alpha 2 adrenergic receptor agonist

Reduces blood pressure by reducing sympathetic tone

Dosing:

Side effects:

Contraindications:

Question 4

Vaccines in pregnancy - rubella

Answer 4

• Part of the MMR (measles, mumps, rubella) vaccine, contains the live attenuated rubella virus
• Preconception - recommend if seronegative. Avoid pregnancy for 28 days after vaccination.
• Antenatally - contraindicated because of the theoretical risk of transmitting rubella to the foetus. However, NO reports of vaccine-induced congenital rubella syndrome; vaccination during pregnancy is not an indication for abortion.
• Postnatally - recommend if seronegative, safe while breastfeeding.

Question 5

Vaccines in pregnancy - influenza

Answer 5

• Quadrivalent (4 virus strains), split virion or subunit vaccines, inactivated influenza virus, egg-based or cell-based
• Recommended in each pregnancy (due to “antigenic drift”, updated vaccine every year), in any trimester
• Benefits
  
  • Maternal - reduced risk complications secondary to influenza (reduced infection rate by ~50%, 65% effective against hospital admissions)
  • Fetal - reduced risk of preterm birth, stillbirth, miscarriage
  • Neonatal - reduced risk of neonatal influenza in first 6 mo (transplacental transfer of antibodies), note infants <6mo not eligible for vaccination (reduced infection rate by ~50%)

Question 6

Vaccines in pregnancy - pertussis

Answer 6

• Part of the dTpa combined vaccine (diphtheria, tetanus and acellular pertussis-containing vaccine)
• Recommended as a single dose in each pregnancy, ideally between 20-32 weeks
• Benefits
  
  • Maternal - reduced risk of pertussis infection
  • Neonatal - reduced risk of neonatal pertussis (via transplacental transfer of antibodies) (reduced risk by 80-91%)

Question 7

Vaccines in pregnancy - COVID

Answer 7

COVID
* Pregnant women with COVID-19 have a higher risk of severe illness (hospitalisation, ICU admission, invasive ventilation), stillbirth and preterm birth
* mRNA vaccines (Pfizer or Moderna) safe in any trimester, no increased risk miscarriage/teratogenicity (based on accumulated real-world evidence)
* Recommend primary course (2 x doses 3-6 weeks apart) and booster dose -> further booster doses discuss with healthcare provider
* Can give at the same time as other vaccinations
* Benefits
* Maternal - significantly reduces risk of COVID-19 infection and risk of transmitting to others including infants
* Fetal - reduced risks of stillbirth and preterm birth
* Neonatal - may provide neonatal protection via transfer of antibodies across placenta or through breastmilk
* No evidence of increased risk of miscarriage or teratogenic risk