Flashcards in Prescribing in Pregnancy Deck (46)
Do most drugs cross placenta?
Yes, except LMW drugs e.g. Heparin
What drugs cross more quickly than others?
Small, lipid soluble
How is absorption effected in pregnancy?
How is distribution effected in pregnancy?
Volume of distribution increased due to increased PV and fat stores
Decreased protein binding, so increased free drug
How is metabolism effected in pregnancy?
Increased liver metabolism of some drugs e.g. phenytoin
How is elimination effected in pregnancy?
Elimination of renally excreted drugs increases- increased GFR
Are pharmacodynamics effected in pregnancy?
No significant changes- pregnant women can be more sensitive to some drugs e.g. hypotension with antihypertensives in 2T
What should be taken pre-conception?
Folic acid 400mcg daily for 3 months prior and first 3 months of pregnancy
Safest drug therapy for existing chronic conditions
When is the period of greatest teratogenic risk?
4th to 11th week
Describe drug use in 1T?
Avoid drugs if at all possible unless maternal benefit outweighs risk to fetus
What teratogenic effects can ACEI/ARBs have?
What teratogenic effects can androgens have?
Virilisation of female fetus
What teratogenic effects can antiepileptics have?
Cardiac, facial, limb, neural tube defects
What teratogenic effects can cytotoxics have?
Multiple defects, abortion
What teratogenic effects can lithium have?
What teratogenic effects can methotrexate have?
What teratogenic effects can retinoids?
Ear, CV, skeletal defects
What teratogenic effects can warfarin have?
Limb and facial defects
What can opiates around term?
What can warfarin cause around term?
What did diethylstilbestrol cause?
Vaginal adenocarcinoma in girls aged 15-20yo whose mothers took drug
Urological malignancy in boys
Can untreated epilepsy lead to congenital malformations?
Yes- incidence higher than that of women without epilepsy
Why does pregnancy increase seizures in 10% of women?
Changes in plasma concentrations of drugs: persistent vomiting, increased clearance
What are frequent seizures during pregnancy associated with?
Lower verbal IQ
Do antiepileptics increase the risk of congenital malformations?
Yes- 20/30% risk if on 4 drugs, monotherapy preferred
Avoid valproate, phenytoin
(96% won't have major malformations)
Are insulin and sulfonylureas safe during pregnancy?
Insulin yes, sulfonylureas no- switch to insulin
What does poor diabetic control increase the risk of?
Do diabetic requirements change during pregnancy?
What can beta blockers do in late pregnancy?
Inhibit fetal growth