Obstetric Pharmacology

Question 1

What are some cardiovascular physiological changes in pregnancy which alter pharmacokinetics?

Answer 1

increase HR, increase SV, increase CO, decrease TPR, decrease MAP, increase blood volume, increase oxygen consumption

Question 2

What are the maternal factors which determine transfer of drugs to fetus?

Answer 2

1. Drug dose
2. Route of administration
3. Maternal metabolism and excretion
4. Maternal protein binding
5. Maternal pH and ionisation of the drug
6. Uterine blood flow

Question 3

What are the functions of placenta?

Answer 3

transport of substances, immunological, metabolism (including of drugs), endocrine

Question 4

What does placental transfer of the drug depend on?

Answer 4

molecular weight, lipid solubility, degree of ionisation

Question 5

Why is fetal metabolism of drugs different to adult metabolism?

Answer 5

because the organ systems are immature

Question 6

What is teratogenicity?

Answer 6

any significant postnatal change in function or form after prenatal treatment

Question 7

What are some examples of teratogenic drugs?

Answer 7

ACE inhibitors, warfarin, tetracyclines, thalidomide, valproic
acid, diethylstilbestrol

Question 8

What is category A for prescribing medicines in pregnancy?

Answer 8

drugs which have been taken by a large number of pregnant women without any proven increase in the frequency of malformation

Question 9

What is category X for prescribing medicines in pregnancy?

Answer 9

drugs which have a high risk of causing damage to the developing fetus

Question 10

What percentage of maternal death is caused by haemorrhage?

Answer 10

25%

Question 11

What drugs are used to manage obstetric haemorrhage?

Answer 11

oxytocin to stimulate uterine contraction and ergometrine to stimulate contraction and vasoconstrict

Question 12

What is preeclampsia?

Answer 12

complicated hypertension in pregnant women where fetal oxygen demand is greater than the maternal oxygen supply

Question 13

What are the long term complications of pre eclampsia?

Answer 13

same as long term complications of hypertension - •Ischaemic heart disease
• Cerebrovascular disease
• Heart failure
• Chronic kidney disease
• Peripheral vascular disease

Question 14

What causes maternal mortality in pre eclampsia?

Answer 14

cerebral complications or cardiovascular failure

Question 15

What drug is used in pre eclampsia for seizures?

Answer 15

magnesium sulphate - used for the treatment and prevention of seizures in women with pre eclampsia

Question 16

What drug is used in pre eclampsia to lower blood pressure?

Answer 16

labetalol