Drugs + Pregnancy Flashcards
Safer medicines in pregnancy and breastfeeding information consortium
Effects of drugs on pregnancy
Fertilisation and implantation - 1st 3 months
Organogenesis - 1st 3 months
Growth and development
Drugs at the end of pregnancy
When looking at the effect of drugs on pregnancy, when is most important to consider
First 3 months
Fertilisation and implantation - 1st 3 months
Organogenesis - 1st 3 months
Amoxicillin Ciprofloxacin Gentamicin Nitrofurantoin Trimethoprim
Nitrofurantoin most appropriate
Stop it - ACEi are almost always contraindicated
Use calcium channel blocker instead etc amlodopine or nifedipine
Or beta blocker - labetalol
Acne in pregnancy is a problem - why
Scaring is a big issue - vitamin A derivates
BUT teratogenicity
Occurs in first three weeks of gestation before pregnancy declares itself
Severe CND, cardiac and craniofacial abnormalities
Not for women of child bearing age unless they practice effective contraception and have received counselling
E.g. isotretinoin (roaccutane)
Sodium valproate - women
Sodium valproate prevention programme in child bearing age
Medicines of teratogenic potential - what is available to help prescribing
Is guidance to aid people in making choices about types of contraception and when to do a pregnancy test
Other drugs which can cause teratogenicity
Alcohol Tetracyclines Warfarin Antibiotics Anti thyroid drugs, anticonvulsants, anti hypertensives Lithium
Pharmacological risks in pregnancy
NSAIDs
Opioids
Antidepressants
Same way as in non-pregnant
Drug absorption in pregnancy
Reduced gastric emptying
Reduced small intestinal mobility
Volume of distribution in pregnancy
Increased Vd during pregnancy which may affect loading dose of drug
Vd = dose/plasma conc
Therapeutic window matters in drugs in pregnancy - why?
Need to meet minimum dose for therapeutic but issue with toxic levels if window is narrow
32 YO pregnant with epilepsy - well controlled on lamotrigine
Develops increasing frequency of seizures at 32 weeks of pregnancy - what is the mechanism
Therapeutic effect decreased
Metabolism - drugs in pregnancy
Why is the 1st trimester the dangerous for using teratogenic drugs?
organogenesis happens, rapidly dividing cells so lots of potential issues
Why are tetracyclines contraindicated in pregnancy?
can get teeth discolouration of the foetus
is trimethoprim safe in pregnancy?
No - folate antagonist affects growth
Is nitrofurantoin safe in pregnancy?
safe early on, some issues in 3rd trimester
Which anti-hypertensives are safe to use in pregnancy? (3)
Labetalol
hydralazine
Nifedipine
Which anti-hypertensive agents are contraindicated in pregnancy?
ace inhibitors
ARBs
why is isoretinoin contraindicated in women of child bearing age?
Teratogenic in first 3 weeks of pregnancy, causes CNS and craniofacial defects
isoretinoin - what is this?
Roaccutane
teratogenic effects of sodium valproate
Neural tube defects
Developmental delay
teratogenic effects of alcohol
Fetal Alcohol syndrome => Leading cause of mental retardation. Also causes micro and holoprosencephaly.
teratogenic effects of lithium
teratogenic effects of lithium
Ebstein’s anomaly (small RV large RA)
teratogenic effects of NSAIDs
premature closure of ductus arteriosus
are opioids safe in pregnancy?
not really, can lead to neonatal respiratory depression especially if used late
Are asthma drugs ok in pregnancy?
Are asthma drugs ok in pregnancy?
yes, benefit outweighs risk for all of them
risk of warfarin in pregnancy
foetal/neonatal haemorrhage
nasal hyperplasia
Why can protein bound drugs be an issue in pregnancy?
relative protein concentration decreases with volume expansion so increased proportion of unbound/active drug
how is hepatic metabolism affected during pregnancy?
some enzyme induction, some are inhibited
