Drug handling in pregnancy

Question 1

EFFECTS OF DRUGS ON PREGNANCY

i) which period of pregnancy is the most important for drugs to be avoided? why?
ii) which drug can leads to cerebral haemmorhage, limb growth in the second trimester?
iii) which drug can cause teeth discolouration in adolescence?
iv) is amoxicillin safe in pregnancy
v) what may be given to a woman with a UTI who is 11 weeks pregnant

Answer 1

i) first three months > most organogenesis (rapid cell turnover)
ii) warfarin
iii) tetracycline > attracted to rapidly dividing bone and teeth > hyperplasia therefore CI in pregnancy and children up to 12 yrs of age
iv) yes
v) nitrofurantoin (safe until third trimester)

Question 2

DRUGS IN PREGNANCY

i) is rampril safe in pregnancy?
ii) which anti hypertensive drugs are safe in pregnancy? (3)
iii) what skin condition can occur in pregnancy? what is the problem with the drugs that are used to treat it? what measures must be in place

Answer 2

i) no - it can affect the babies kidneys, especially in second and third trimester (ACE i and ARBs are CI in pregnancy)

ii) CCBs eg nifedipine, BBs eg labetalol (works on alpha and beta receptors - mixed) methyldopa (has lots of SE, crosses BBB)
- labetatlol is usually given first

iii) acne vulgaris > use vitamin A derivatives that are very teratogenic
- occurs in first three weeks of gestation > women of child bearing age must be on effective contraception
- roaccutane

Question 3

OTHER TERATOGENIC DRUGS

i) what can anti thyroid drugs cause?
ii) what can lithium cause?
iii) what can NSAIDs lead to in the fetal heart?
iv) what can opioids and anti depressants cause?
v) are asthma drugs safe in pregnancy?

Answer 3

i) hypothyroidism in neonates
ii) cardiac abnormalities
iii) premature closure of ductus arteriosus - maintained opened by prostaglandins until birth (NSAIDs can reduce PG levels and lead to closure) > lungs not mature and decreased oxygenation
iv) respiratory depression in the neonate and they may have withdrawal symptoms
v) yes - the risk of not treating outweighs the risk of treatment

Question 4

EFFECTS OF PREGNANCY ON DRUGS

i) how is gastric emptying and small intestine motlity affected?
ii) which two routes may enhance the effect of a prescribed drug
iii) how are lipid solubility and protein binding affected? what effect does this have on vol of distribution
iv) what effect does pregnancy have on cytochrome P450 enzymes?
v) how is renal plasma flow affected? how does this affect drug clearance

Answer 4

i) both are reduced > may impair drug absorption
ii) inhaled or intra muscular route (increased blood supply to these areas)

iii) affects volume of distribution
- increased lipid solubility - may want lower doses of lipid sol drugs
- intravasc spaces are increased > affects conc of protein in the blood
- increased Vd during pregnancy - may affect loading doses of drugs

iv) can induce or inhibit these - depends on the drug (look at the effect its having and you can work it out)
v) increased renal plasma flow > may increase drug excretion and reduce half life