Week 5- Prescribing in pregnancy Flashcards
NOTE
No drug is completely safe in pregnancy. So how do you know which drugs you can use. First consider non-pharmalogical methods
When would you prescribe drug therapy in a pregnant women?
When the benefits outweigh the risks.
NOTE- most drugs aren’t licensed in pregnancy- prescribe outwit license.
Which drugs aren’t likely to cross the placenta?
Large molecular weight drugs.
Which drugs cross the placenta quickly?
Small, lipid soluble drugs.
In pregnancy, what might affect the absorption of a drug?
Morning sickness may reduce absorption of a drug.
Also the increased plasma volume and fat stores means the volume of distribution increases
In pregnancy, what might affect the distribution of a drug?
Decreased protein binding means more free drug.
In pregnancy, what might affect the metabolism of drugs?
Increased liver metabolism of some drugs.
What may affect the elimination of drugs in a pregnant women?
Increased renal excretion due to increased GFR.
Does anything change in pregnant women with regards to pharmacodynamics?
No significant changes- pregnant women may become more sensitive to certain drugs.
Example- hypotension with antihypertensives in 2nd trimester.
What should you give a women with suspected pregnancy, or who is planning a pregnancy?
400mcg of folic acid 3 months prior to pregnancy and in the first three months of pregnancy.
When is the period of greatest teratogenic risk? in this period how should you handle drug therapy?
4th-11th week.
Avoid drugs if possible, unless the benefits outweigh the risk to the foetus.
what do ACE inhibitors/ARBs do in pregnancy?
They are teratogenic and cause renal hypoplasia.
What do androgens do in pregnancy?
Teratogenic- cause virilisation of the female fetus.
What do anti epileptics do in pregnancy?
Teratogenic- cardiac, facial, limb, and neural tube defects.
What do cytotoxics do in pregnancy?
Teratogenic- cause multiple defects, abortion.
What does lithium do in pregnancy?
Teratogenic- causes cardiovascular defects.
What does methotrexate do in pregnancy?
Teratogenic- causes skeletal defects.
What do retinoids do in pregnancy?
Teratogenic- cause ear, cardiovascular or skeletal defects.
What does warfarin do in pregnancy?
Teratogenic- causes limb and facial defects.
What drug can cause respiratory depression?
Opiates.
What drug can cause bleeding in labour?
Warfarin
What drugs can cause withdrawal symptoms?
Opiates
SSRI’s.
NOTE
In epilepsy- the incidence of congenital malformations is higher in untreated epilepsy than in women without epilepsy.
There are increased seizures in 10% of women.
Why are there increased seizures in 10% of women in pregnancy?
Non-compliance
Decreased plasma concentration of drug- persistent vomiting, increased clearance
Are there any consequences with increased seizures in pregnancy?
Associated with lower IQ, hypoxia, bradycardia, antenatal death, maternal death.
What should the approach to treating epilepsy during pregnancy be?
The risk increases by 20-30% if you are on 4 therapies so try mono therapy.
Which epileptic drugs should be avoided?
Sodium valproate
Phenytoin
Is insulin thought to be safe in pregnancy?
Yes.
Do you need to change doses of insulin during pregnancy?
Requirements of insulin change.
What diabetic drug is not safe in pregnancy? What should you change them to?
Sulfonylureas
Change to insulin.
Which antihypertensive drugs are used in pregnancy?
Labetalol
Methyldopla
Nifedine
What anti-hypertensive medication should you avoid during pregnancy?
ACE inhibitors and ARBs
Why antihypertensive may inhibit foetal growth in late pregnancy?
Beta blockers.
What drug would you give for nausea and vomiting?
Cyclizine
What drug would you give for a UTI?
Follow the local guidelines
Nitrofurantoin, cefalexin,
What drug should you give for pain in pregnancy?
Paracetamol
What drug should you give for heartburn in pregnancy?
Antacids.
NOTE
All pregnant women are at a 10 fold increase of VTE in pregnancy. All women should have their VTE risk assessed in pregnancy.
What should women with significant VTE risk factors be given?
Low molecular weight heparin.
How would you treat a DVT or PE in pregnancy?
What drug should you avoid?
Low molecular weight heparin.
Avoid warfarin- teratogenic.
Which types of drugs are more likely to enter breast milk?
Small molecules
Fat soluble drugs
What is fore milk rich in?
Protein
What is hind milk rich in?
Higher fat content
NOTE
Some drugs are concentrated in breast milk.
What can amiodarone cause if transferred through breast milk?
Neonatal hypothyroidism.
What can cytotoxic drugs cause if transferred through breast milk?
Bone marrow suppression
What can benzodiazepines cause if transferred through breast milk?
Drowsiness.
What can bromocriptine cause if transferred through breast milk?
Suppress lactation.
Which antibiotic, not safe for use in pregnancy, can stain teeth?
tetracycline.
Which anti epileptic drug is mostly associated with cleft palate?
phenytoin.
