Prescribing In Special Groups 1 Flashcards
(48 cards)
What is the time during pregnancy wheere the foetus is at high risk
First trimester
What is a general advice about treating a disease that may affect pregnancy
It is better to not stop the drug is the disease can affect the pregancy e.g epilepsy, hypertension
In pregancy which factor of pharmokinetics changes
Absorption
How does absorption change in pregnancy
- Large foetus can affect gastric emptying and gut transit time
- muscle blood flow changes so IM injection absorption can be increased
What are teratogens
Substance, organism, physical agents or deficiency state capable of inducing abnormal structute of function such as gross structural abnormalities, functional deficiency e.g deafness, intrauterine growth restriction
What are the causes of congenital malformation
Unknown Multifactorial Maternal illness Genetic Teratogenic
What is the first 2 weeks in pregnancy known as
All or nothing effect
What is the all or nothing effect
The embryo either recovers or spontanous loss can occur
Which time period is the time with highest risk for drugs to cause congenital malformation
3-8 weeks
Why does 3-8 weeks of pregnancy have a high risk of congential malformation due to drugs
This is the time period when the organs form
What is the 2nd to 3rd timester known as
Growth phase
What affect can drugs have from 2nd to 3rd trimester
Fetotoxicity
What is fetotoxicity
When the drugs affect the growth or have toxic effects on tissue
What are the rules in prescribing during pregnancy
- Assume all drugs will cross the placenta unless they have a high molecular wight e.g heparin
- Try to avoid drugs in the first trimester
- Avoid drugs known to be harmful and only prescibe if the benefit to mother outweighs harms to fetus e.g antiepileptics
- Check all drugs in the BNF
List the drug class that you need to avoud in the first trimester of pregnancy
Androgens Cytotoxic drugs Lithium Quinolone antibiotics Retinoids Sodium valproate Thalidomide Warfarin
Which drug class has the highest risk of teratogenic effect in the first trimester
Sodium valproate
Which drug clasess should be avoided in second to third trimester in pregnancy
Ace inhibitors and arbs Aminoglycosides NSAIDs and aspirin Opiates and benzodiazepines Sulphonamides Tetracyclines
What adverse effect can aceinhibitors have on the foetus
The aminiotic fluid is what the baby pees, the ace inhibitro can act on the RAAS so they fetus doesnt pee as much and this causes less fluid aroung the baby, this is known as oligohydramnios
What is the effect of tetracycline in the fetus
Tetracycline binds to calcium and cause yellow discolouration of the teeth
Also inhibits bone growth
What might need to be done to the doses of drugs in pregnancy
Increased
Is avoiding breastfeeding to take prescribed drugs a good option
No because the benefits of breast feeding will be lost such as immunitty and reduced risk of allergy in the infant
Before prescribing in breastfeeding what needs to be considered
Amount of drug delivered to infant in breast milk Infant pharmocokinetics (ADME) Infant pharmocodynamic (effect of drug on infant)
What drug characteristics have a reduced passage into the breast milk
High molecular weight
High protein binding
Low lipid solubility
Low ph
Which drugs have a high molecular weight
Insulin and heparins
