Pharmacology in Pregnancy & Breast feeding

Question 1

What changes occur to pharmacokinetics during pregnancy?

Answer 1

1 - Absorption

2 - Distribution

3 - Metabolism

4 - Excretion

Question 2

What changes occur to pharmacodynamics during pregnancy?

Answer 2

• Pregnancy may affect site of action & receptor response to drugs
• Efficacy of drugs may be different
• Adverse effects may be different

Question 3

What are the main concerns regarding the use of medication during pregnancy & breastfeeding?

Answer 3

1) Teratogenicity (1st trimester)
2) Fetotoxicity (2nd and 3rd trimester)
3) Drugs and breast milk - important to know what concentration of drug will be present in breast milk

Question 4

Where can information be found about risks with specific drugs in pregnancy/breast feeding?

Answer 4

SPC - Schedule of product characteristics

UK Tetrology service

Drugs and Lactation database

BNF

Question 5

What are the general principles of prescribing for pregnant patients?

Answer 5

1) Try non-pharmacological treatment 1st
2) Use drugs with best safety records
3) Check SPC for up todate information
4) Use lowest effective dose
5) Use drug for shortest possible time
6) Avoid first 10 weeks of pregnancy
7) Consider stopping or reducing dose before delivery
8) Don’t under treat maternal diseases that may be harmful to the fetus

Question 6

What are the general principles of prescribing for breast-feeding patients?

Answer 6

1) Avoid unnecessary drug use
2) If licensed as safe for paeditaric use, likely to be safe for breast feeding
3) Highly protein binding drugs

Question 7

What physiological changes of pregnancy affect drug absorption in the mother?

Answer 7

• Increased gastric emptying and gut motility
• Increased blood flow
• Increased CO
• Decreased Tidal volume

Question 8

What physiological changes of pregnancy can effect drug distribution?

Answer 8

• Increased plasma volume
• Greater dilution of plasma

Question 9

What physiological changes of pregnancy can effect drug metabolism?

Answer 9

• Oestrogen and progestogens induce Liver P450 enzymes therefore increasing metabolism

Question 10

What physiological changes of pregnancy can effect drug excretion?

Answer 10

• GFR increased by 50%

Question 11

What properties of drugs affects how easily drugs are transferred across the placenta?

Answer 11

1 - Molecular weight

2 - Polarity

3 - Lipid solubility

Question 12

What are the most common mechanisms by which drugs can cause teratogenicity during pregnancy?

Answer 12

1 - Folate antagonism

2 - Neural Crest Cell disruption

Question 13

What are examples of drugs that cause folate antagonism?

Answer 13

Methotrexate

Trimethoprim

Question 14

What defects to the fetus occur due to folate antagonism?

Answer 14

Neural tube defects

Question 15

Which drugs cause neural crest cell disruption during pregnancy?

Answer 15

Retinoid drugs, e.g. isotretinoin for acne

Question 16

What are common abnormalities cause by neural crest cell disruption?

Answer 16

Aortic arch anomalies

Ventricular septal defects

Question 17

Which drugs can cause enzyme-mediated teratogenesis during pregnancy?

Answer 17

NSAID’s

Question 18

What fetal defects are caused by NSAID use during pregnancy?

Answer 18

Orofacial clefts

Question 19

What drugs can cause fetotoxicity during pregnancy?

Answer 19

ACE-inhibitors

Question 20

What fetal abnormalities can occur from fetotoxicity caused by ACE-i’s?

Answer 20

Growth retardation

Structural malformations

Question 21

What are the categories of drugs that can be used in pregnancy and which are the most safe and which are most dangerous?

Answer 21

A - most safe

B

C

D

X - most dangerous

Question 22

What are the known teratogens to avoid during pregnancy?

Answer 22

1 - Sodium Valproate

2 - Warfarin

3 - ACE-I’s

4 - Alcohol

5 - Isotretinoin (retinoids)

Question 23

What are the drugs to avoid during breastfeeding?

Answer 23

1 - Cytotoxics

2 - Immunosuppressants

3 - Anti-convulsants