Antenatal Care: Medications in Pregnancy Flashcards
Mechanism of NSAIDs?
1) Inhibits synthesis of prostaglandin from arachidonic acid by inhibiting cyclo-oxygenase (COX)
2) COX-1 –> stimulates prostaglandin synthesis that is essential to preserve integrity of gastric mucosa, maintains renal perfusion & inhibits thrombus formation at vascular endothelium (i.e. inhibition of COX-1 increases risk of bleeding, can cause AKI, and increases risk of peptic ulcers).
3) o COX-2 –> expressed in response to inflammatory stimuli and stimulates production of prostaglandins that cause inflammation and pain (i.e. inhibition of COX-2 reduces pain and inflammation)
The therapeutic benefits of NSAIDs are principally mediated by COX-2 inhibition and adverse effects by COX-1 inhibition
Side effects of NSAIDs?
- GI toxicity e.g. peptic ulcer disease, GI bleeding
- Renal impairment
- Increased risk of CVS events e.g. MI, stroke
Contraindications of NSAIDs?
- Severe renal impairment
- Heart failure
- Liver failure
- NSAID hypersensitivity
- Peptic ulcer disease
- GI bleeding
What drugs can increase the risk of peptic ulceration when given alongside NSAIDs?
1) corticosteroids
2) aspirin
What drugs can increase the risk of GI bleeding when given alongside NSAIDs?
1) Anticoagulants e.g. warfarin, DOACs
2) SSRIs
3) Venlafaxine
What drugs can increase the risk of renal impairment when given alongside NSAIDs?
1) ACEi
2) Diuretics
How do NSAIDs impact other antihypertensives ?
NSAIDs reduce therapeutic effects of other antihypertensives
In pregnancy, what are prostaglandins important for?
1) Maintain the ductus arteriosus in the fetus and neonate
2) Soften the cervix and stimulate uterine contractions at the time of delivery.
Are NSAIDs safe in pregnancy?
NSAIDs are generally avoided in pregnancy unless really necessary (e.g. in rheumatoid arthritis).
In what trimester are NSAIDs particularly avoided? Why?
3rd trimester:
1) can cause premature closure of the ductus arteriosus in the fetus.
2) can also delay labour
What is the most frequently used beta-blocker in pregnancy?
Labetalol
1st line management of HTN caused by pre-eclampsia?
Labetalol
3 adverse effects of beta blockers in pregnancy?
1) Fetal growth restriction
2) Hypoglycaemia in the neonate
3) Bradycardia in the neonate
How can medications that block the renin-angiotensin system (ACE inhibitors and ARBs) affect pregnancy?
Can cross the placenta and enter the fetus.
1) In the fetus, they mainly affect the kidneys, and reduce the production of urine (and therefore amniotic fluid).
2) The other notable effect is hypocalvaria, which is an incomplete formation of the skull bones.
2 main adverse effects of ACEi and ARBs in pregnancy?
1) affect kidneys of foetus and reduce production of urine (and theremore amniotic fluid)
2) hypocalvaria
What is hypocalvaria?
An incomplete formation of the skull bones.
What adverse effects can ACEi and ARBs cause when used in pregnancy?
1) Oligohydramnios (reduced amniotic fluid)
2) Miscarriage or fetal death
3) Hypocalvaria (incomplete formation of the skull bones)
4) Renal failure in the neonate
5) Hypotension in the neonate
Adverse effects of use of opioids during pregnancy?
Withdrawal symptoms in the neonate after birth –> neonatal abstinence syndrome (NAS).
How does neonatal abstinence syndrome (NAS) present?
NAS presents between 3 – 72 hours after birth with:
a) irritability
b) tachypnoea
c) high temperatures
d) poor feeding.
Is warfarin safe during pregnancy?
No - teratogenic
Adverse effects of using warfarin in pregnancy?
1) foetal loss
2) congenital malformations, particularly craniofacial problems
3) bleeding during pregnancy, postpartum haemorrhage, fetal haemorrhage and intracranial bleeding
Adverse effects of sodium valproate in pregnancy?
neural tube defects and developmental delay.
Rules around sodium valproate in women?
There are strict rules for AVOIDING sodium valproate in girls or women unless there are no suitable alternatives and strict criteria are met to ensure they do not get pregnant. There is a specific program called Prevent (valproate pregnancy prevention programme) to ensure this happens.
Adverse effects of lithium in pregnancy?
Risks and benefits carefully weighed up by psychiatrist.
1st trimester –> linked with congenital cardiac abnormalities e.g. Ebstein’s anomaly
