Prescribing in Pregnancy

Question 1

is medicine used commonly in pregnancy

Answer 1

yes

Question 2

inherent risks during pregnancy (without medication use)

Answer 2

• miscarriage: 15%
• congenital anomalies: 2-3% at birth; 5% at 5 years of age

Question 3

% of birth defects that medication accounts for

Answer 3

~1%

Question 4

for a drug to be classified as teratogen, should meet 4 characteristics:

Answer 4

• cause a PATTERN of birth defects
• cause defects dependent on time of exposure
• cause birth defects in a dose dependent manner
• cause defects in genetically susceptible individuals

Question 5

what do the 4 characteristics suggest that make for the classification of teratogen

Answer 5

=> suggest a biologically plausible mechanism of teratogenicity for a particular drug

Question 6

define teratogen

Answer 6

• agent or factor that causes malformation of an embryo

Question 7

[dose response relationship] => teratogenous drug needs to display a dose threshold which means….

Answer 7

• exposures below a certain level do not result in an effect (birth defect)
• dose not always known

Question 8

what 2 factors are involved in the Dose Response Relationship (a characteristic in teratogens)

Answer 8

• dose threshold
• dose response

Question 9

[dose response relationship] => teratogenous drug needs to display a dose response which means….

Answer 9

• demonstrated increased effect with increasing dose

Question 10

[time of exposure] when teratogenous drug exposure in 1st trimester, tend result in _____ because….

Answer 10

• malformations
• because main period of organogenesis in foetus

Question 11

[time of exposure] when teratogenous drug exposure in 2nd and 3rd trimester, tend result in _____ because….

Answer 11

• growth, neurobehavioural, etc issues
• because this when growth and maturation of organ systems

Question 12

[timing of exposure] can same drug, giving at different times in pregnancy, have different risks of same and / or different adverse event/s

Answer 12

• yes
• drug has periods of varied susceptibility

Question 13

[timing of exposure] what abnormalities can retinoids (teratogenic) lead to

Answer 13

isotretinoin embryopathy
- facial dysmorphia (mental health condition)
- cleft palate
- external ear abnormalities
- eye abnormalities
- cardiovascular abnormalities

Question 14

[timing of exposure] what is exposure window of retinoids

Answer 14

unknown

Question 15

[timing of exposure] when is exposure window of warfarin

Answer 15

week 6-12

Question 16

[timing of exposure] dose response in warfarin

Answer 16

worse effects in exposures >5mg

Question 17

[timing of exposure] what can warfarin (teratogenic) lead to

Answer 17

foetal warfarin syndrome
- nasal hyperplasia
- skeletal abnormalities resulting in short limbs and digits

(note: warfarin - anticoagulant to prevent formation blood clots in legs, lungs, heart, brain; can cause serious bleeding)

Question 18

[timing of exposure] what can phenytoin (teratogenic) lead to

Answer 18

foetal hydantoin syndrome
- craniofacial dysmorphisms (abnormal body structure)
- digital and nail hyperplasia
- orofacial clefts
- cardiac defects

Question 19

what is phenytoin used for & is it still used during pregnancy

Answer 19

• seizure control
• important to have adequate seizure control, risk-to-benefit may be necessary to use even though not preferred

Question 20

what considerations can make a drug still used during pregnancy (outside exposure window)

Answer 20

• risk to benefit
  > incl importance of treating condition
  > incl if there other, safer options

Question 21

is the ADEC Categories a reliable resource? why / why not?

Answer 21

• no
  why?
• simplistic, does not consider: dose, timing, patient, condition, route
• not regularly updated
• confusing categories

Question 22

what is an issue with Consumer Medicines Information

Answer 22

• patient have access to info
  (doc not going to rely on for drug info]
• info can be contradictory or conflict with practice

Question 23

how can you handle patient with conflicting info from Consumer Medicines Information

Answer 23

• communicate discrepancy with patient if they are accessing that sort of information
• letting patient know about practice guideline use of that drug

Question 24

why is Product Information a less relaible resource

Answer 24

• is company sponsored and so is conservative

Question 25

what resource can you use for information about prescribing a medication in pregnancy if time poor for own research using reliable resources

Answer 25

SA Health Medicines Information Service
- accessible to health professionals and consumers

Question 26

use of lithium carbonate for mental health management; what is the risk / benefit analysis

Answer 26

usually continued during pregnancy
ie/ condition they have if not treated poses more risk to the pregnancy (bipolar)

Question 27

what is the adverse outcome of lithium carbonate

Answer 27

Ebstein’s Anomaly (cardiac defects)

Question 28

is SSRIs (mental health treatment - depression) considered safe during pregnancy and why

Answer 28

yes
because relative risk vs absolute risk (of treatments adverse outcomes)

Question 29

Drug Classes to AVOID in pregnancy (contraindicated in pregnancy but remember clinical context dependent)

Answer 29

• ACE-inhibitors (completely avoided; usually used for heart and kidney conditions)
• angiotensin receptor blockers (completely avoided; usually used for heart conditions or and kidney conditions in diabetics)
• immunosuppressants and immunomodulators (avoided)
• anti-epileptics (switch to safer options if can)
• NSAIDs (tend to be avoided for standard indications like pain)

Question 30

what adverse outcomes from ACE-inhibitors during pregnancy

Answer 30

• severe effects on developing foetal kidney
• can result in foetal death

Question 31

what adverse outcomes from angiotensin receptor blockers during pregnancy

Answer 31

• can result in foetal death

Question 32

what adverse outcomes immunosuppressants and immunomodulators in pregancny

Answer 32

• severe foetal effects

Question 33

if on immunosuppressants or immunomodulators, what is recommended prior to becoming pregnant

Answer 33

• therapy free intervals
• so some planning required prior to pregnancy

Question 34

what adverse outcomes associated with anti-epileptics in pregnancy

Answer 34

• increased rates of malformations
• neurodevelopmental abnormalities

Question 35

what are the considerations when it comes to anti-epileptics in pregnancy

Answer 35

• seizure control is paramount
• there are safer medication alternatives for treatment of seizure <- pre-pregnancy planning to switch to alternative
• may not be able to switch: risk-benefit-analysis

Question 36

NSAID exposure window time & adverse effects

Answer 36

• paracetamol (NSAID) exposure after 20 wks gestation
• renal toxicity in foetus
• premature closure of ductus arteriosus w/ possible links to persistent pulmonary hypertension of newborn

Question 37

when would NSAIDs used during pregnancy

Answer 37

sometimes used therapeutically eg/ after procedure