Prescribing in Pregnancy Flashcards
When, in pregnancy, does development of the limbs and organs occur?
Very early on
What could be considered instead of antidepressants?
CBT
If benefits outweigh risks …
Prescribe
> ___% of women take drugs in pregnancy
90
Do most drugs cross the placenta?
Yes
What drugs don’t cross the placenta?
Drugs of large molecular weight e.g. heparin
What type of drugs cross the placenta more quickly?
Small, lipid-soluble drugs
What is pharmacokinetics?
What the body does to a drug – Absorption, Distribution, Metabolism, Elimination
What may absorption of a drug be affected by?
Morning sickness
What happens to volume of distribution during pregnancy?
Vd increases – due to increased plasma volume and fat stores
What happens to level of free drug during pregnancy?
Increased free drug – due to decreased protein binding.
What happens to liver metabolism of some drugs during pregnancy?
Increased liver metabolism of some drugs e.g. phenytoin.
What happens to GRF during pregnancy?
Increased GFR – due to increased elimination of renally excreted drugs
Give 2 examples of drugs for which the concentrations may need to be checked and the dose altered during pregnancy and after delivery.
- Lithium
* Digoxin
What is pharmacodynamics?
What the drug does to the body
What is the effect of pregnancy on pharmacodynamics?
Doesn’t cause any significant changes
What is the effect of pregnancy on pharmacodynamics?
Doesn’t cause any significant changes
BUT, pregnant women may be more sensitive to some drugs
When should folic acid be given and how much?
400mcg daily for 3 months prior and first 3 months of pregnancy
What is there a risk of in the 1st trimester?
Miscarriage
What is the important process that takes place during the 1st trimester?
Organogenesis.
When is the period of greatest teratogenic risk?
4th -11th week
What do ACEI’s/ARB’s do to the foetus?
Renal hypoplasia
What do androgens do to the foetus?
Virilisation of the female foetus
What do antiepileptics do to the foetus?
Cardiac, facial, limb, neural tube defects
What do cytotoxic do to the foetus?
Multiple defects, abortion
What does lithium do to the foetus?
CVS defects
What does methotrexate do to the foetus?
Skeletal defects
What do retinoids do to the foetus?
Ear, cardiovascular, skeletal defects.
What does Warfarin do to the foetus?
Limb and facial defects
What happens – in terms of foetal development – in the 2nd and 3rd trimesters?
- Growth of foetus.
* Functional development: intellectual impairment; behavioural abnormalities.
Give examples of how drugs taken around term may have adverse effects on labour.
- Slow progress of labour.
- Adaptation of foetal circulation may be affected – premature closure of ductus arteriosus.
- Suppression of foetal systems – opiates cause respiratory depression.
- Bleeding – warfarin.
What adverse effect on baby after delivery may occur if drugs are taken around term?
- Withdrawal syndrome – opiates, SSRI.
* Sedation.
What is Diethylstilbestrol used for?
Prevention of recurrent miscarriage (didn’t actually work) from 1940-1971.
In what % of women do seizures increase during pregnancy? Why?
10%.
- non-compliance.
- changes in plasma concentrations of drugs: persistent vomiting, increased clearance.
