Pharmacology in pregnancy and breastfeeding

Question 1

What are some problems with oral route meds in pregnancy?

Answer 1

May be difficult if there is morning sickness, nausea or vomiting
Potential decrease in gastric emptying and gut motility

Question 2

What is a problem with IM route for meds during pregnancy?

Answer 2

Blood flow increased so absorption may increase via this route

Question 3

Name a drawback of inhalation as a route for meds during pregnancy.

Answer 3

Increased cardiac output and decreased tidal volume may cause increased absorption via this route

Question 4

How may pregnancy affect distribution of drugs?

Answer 4

Increased plasma volume and fat

Greater dilution of plasma will decrease relative amount of plasma proteins

Question 5

What effect does oestrogen and progestogens have on metabolism?

Answer 5

Can induce or inhibit p450 enzymes, increasing or reducing metabolism

Question 6

What is the effect of altered metabolism from oestrogen and progestogens on the body drugs?

Answer 6

Levels may be reduced if metabolism induced

Levels may increase if metabolism inhibited

Question 7

How does pregnancy affect GFR?

Answer 7

Increased by 50%

Question 8

What travels across the placenta from mother to fetus?

Answer 8

Oxygen 
Glucose
Amino acids
Lipids, FA's, Glycerol
Alcohol
Nicotine and other drugs
Viruses
Antibodies

Question 9

What travels across the placenta from fetus to mother?

Answer 9

CO2
Urea
Waste

Question 10

Name some factors affecting placental drug transfer?

Answer 10

Physiochemical properties (molecular weight, polarity, lipid solubility)
Transfer rate
Duration of exposure
Distribution
Stage of development
Effect of drugs when used in combo

Question 11

How are drugs excreted in the fetus?

Answer 11

Excreted into amniotic fluid which is then swallowed and recirculated

Question 12

What are some important principles of prescribing in pregnancy?

Answer 12

Non-pharmacological treatment preferable
Use lowest effective dose
Use drug for shortest time possible
Avoid in first 10 weeks of pregnancy ideally
Consider stopping reducing dose before delivery

Question 13

When does teratogenicity pose the greatest risk for fetal abnormality?

Answer 13

Organogenesis

Weeks 3-8

Question 14

What are folates for?

Answer 14

Essential for the synthesis of DNA, the modification of DNA and RNA, the synthesis of methionine from homocysteine, and various other chemical reactions involved in cellular metabolism

Question 15

How do methotrexate and trimethoprim cause folate antagonism?

Answer 15

Block conversion of folate to THF by irreversibly binding to the enzyme

Question 16

How do phenytoin, carbamazepine and valproate cause folate antagonism?

Answer 16

Block other enzymes in the folate pathway

Question 17

What kind of defects could folate antagonism cause?

Answer 17

Neural tube, oro-facial or limb defects

Question 18

What kind of drugs may cause neural crest disruption?

Answer 18

Retinoids

Question 19

What are some problems which could arise from neural crest disruption?

Answer 19

Aortic arch abnormalities
VSD's
Craniofacial malformations
Oesophageal atresia
Pharyngeal gland abnormalities

Question 20

Give an example of enzyme-mediated teratogenesis.

Answer 20

NSAIDs causing orofacial clefts and cardiac septal defects

Question 21

What may cause fetotoxicity?

Answer 21

ACE inhibitors/ARBs could cause renal dysfunction and growth retardation

Question 22

Can drugs a mother takes be present in breast milk?

Answer 22

Yes

Most will

Question 23

List some drugs should be avoided in pregnancy?

Answer 23

Cytotoxics
Immunosuppressants
Anti-convulsants
Amiodarone
Lithium
Radio-iodine

Question 24

Can herbal medicines affect pregnancy?

Answer 24

Yes

Some common ones include fenugreek, ginseng, rhubarb, star anise