15 - Pharmacology in Pregnancy & Breastfeeding

Question 1

% of women of child-bearing age take medications?

Answer 1

80%

Question 2

name 4 common conditions women take medications for?

Answer 2

hypertension

epilepsy

asthma

mental health disorders

Question 3

what are the 4 factors involved in the kinetic processes?

Answer 3

absorption

distribution

excretion

metabolism (elimination)

Question 4

give 3 reasons why oral route is often difficult for pregnant women?

Answer 4

morning sickness

decreased gastric emptying

decreased gut motility

Question 5

describe 2 other routes for pregnant women to use?

Answer 5

intramuscular

inhalation

Question 6

why do intramuscular drugs have increased absorption for pregnant women?

Answer 6

blood flow is increased

Question 7

why do inhaled drugs have increased absorption for pregnant women?

Answer 7

increased cardiac output and decreased tidal volume

Question 8

what 2 factors result in change in distribution of drugs?

Answer 8

increased plasma volume

increased fat

Question 9

what results in decreased relative amount of plasma proteins?

Answer 9

increased dilution of plasma

Question 10

what is the effect of progesterone & oestrogen on metabolism?

Answer 10

they inhibit OR induce liver P450 enzymes

therefore increase/ decrease metabolism

Question 11

describe pregnancy’s effects on GFR?

Answer 11

GFR increases in pregnancy by 50%

Question 12

what is the result on this change of GFR during pregnancy?

Answer 12

GFR increases

therefore, increased excretion of drugs

Question 13

do drugs cross the placenta?

Answer 13

MOST of them do

Question 14

name 4 factors affecting a drugs’ ability to cross the placenta?

Answer 14

drug’s physiochemical properties

rate @ which drug crosses placenta

duration of drug exposure

stage of placental & foetal development

Question 15

3 factors which affect placental transfer?

Answer 15

molecular weight (small - cross easily)

polarity (unionised - cross easily)

lipid solubility (lipid soluble - cross easily)

Question 16

what action might the placenta have on some drugs?

Answer 16

it may metabolise them

Question 17

why is distribution in foetus different to that of an adult?

i.e. why is there more free drug available

Answer 17

less protein binding

less fat

increased blood flow to brain

Question 18

why is foetus enzyme activity decreased?

Answer 18

foetus exhibits different p450 enzymes

metabolism and enzyme activity increases with gestation

Question 19

describe foetal excretion?

Answer 19

foetus excretes drug into amniotic fluid - foetus then swallows this - therefore RECIRCULATION

Question 20

what does the foetus’ excretion method then cause?

Answer 20

accumulation of substances in amniotic fluid

Question 21

what is the result of the placenta not functioning at delivery?

Answer 21

issues with excretory function

Question 22

most drugs have little data to understand their dosing - name 4 groups of medications which are relatively understood?

Answer 22

anti-convulsants

anti-hypertensives

analgesics

antibacterials

Question 23

when is the highest risk of teratogenicity during pregnancy and why?

Answer 23

1st trimester - @ 3-8 weeks - organogenesis

Question 24

name 3 mechanisms for teratogenicity?

Answer 24

folate antagonism

neural crest cell disruption

oxidative stress

Question 25

name 3 possible issues associated with fetotoxicity?

Answer 25

growth retardation

structural malformations

foetal death

Question 26

name 2 types of medications and possible effects of these on the foetus?

Answer 26

ACEIs & ARBs - renal dysfunction, growth retardation

Question 27

name 5 principles of prescribing for women of child-bearing age?

Answer 27

1 - consider possibility of pregnancy

2 - warn women of risks

3 - advise women with other conditions to attend before planning pregnancy

4 - discuss contraception

5 - do not prescribe without contraception if possible

Question 28

name 8 principles of prescribing during pregnancy?

Answer 28

1 - try non-pharmacological treatment first

2 - use drug with best safety record

3 - check SPC for up to date info

4 - use lowest effective dose

5 - use drug for shortest possible time (and intermittent)

6 - avoid 1st 10 weeks if possible

7 - consider stopping/ reducing dose before delivery

8 - never under-treat a disease which is harmful

Question 29

what advice should be given re herbal remedies during breast feeding?

Answer 29

avoid them

Question 30

which herbal medications are hepatotoxic?

Answer 30

those with pyrrolizidine alkaloids