Pharmacology in Pregnancy and Breastfeeding

Question 1

What are the principles of prescribing for women of childbearing age?

Answer 1

• Always consider possibility of pregnancy (planned or not!)
• Warn women of possible risks
• When treating medical conditions, advise women to attend before getting pregnant if planning to (optimise treatment)
• Discuss contraception
• If necessary, do not prescribe without contraception

Question 2

What are the principles of prescribing for pregnant women?

Answer 2

• If you can, try non-pharmacological treatment first
• Use the drug with the best safety record (avoid new drugs unless proven safe)
• Check the SPC for the most up to date information
• Use the lowest effective dose
• Use the drug for the shortest possible time, intermittently if possible
• Avoid the first 10 weeks of pregnancy if possible
• Consider stopping or reducing dose before delivery
• Don’t under treat disease which may be harmful to the fetus

Question 3

What are the principles of prescribing for women who are breast-feeding?

Answer 3

• Avoid unnecessary drug use
• Check on up to date drug information
• May be a lack of information
• If licensed and safe in paediatric use (esp under 2 years), a drug is likely to be safe in breast feeding
• Choose drugs with pharmacokinetic properties that reduce infant exposure (eg highly protein bound)

Question 4

Give three variables of a drug molecule that will determine whether or not it can cross the placenta

Answer 4

• Molecular weight (smaller sizes cross more easily)
• Polarity (non-polar cross more readily)
• Lipid solubility (lipid-soluble drugs will cross)

Question 5

When is the risk of teratogenicity the greatest?

Answer 5

During organogenesis; 3-8 weeks gestation (first trimester)

Question 6

What are the potential teratogenic effects of retinoid drugs such as isotretinoin?

Answer 6

aortic arch anomalies 
ventricular septal defects
craniofacial malformations
oesophageal atresia 
pharyngeal gland abnormalities

Question 7

Give three potential teratogenic effects of NSAIDs

Answer 7

Orofacial clefts
Cardiac septal defects
Premature closure of the ductus arteriosus

Question 8

Give six examples of known teratogens

Answer 8

Anticonvulsants
Anticoagulants
Antihypertensive agents
NSAIDs
Alcohol
Retinoids

Question 9

What are the potential teratogenic effects of anticonvulsants? GIve examples of teratogenic anticonvulsants

Answer 9

Sodium valproate
Carbamazepine
Phenytoin

Associated with neural tube defects

Question 10

What are the potential teratogenic effects of anticoagulants? Which anticoagulant is particularly teratogenic?

Answer 10

Warfarin

Associated with haemorrhage in the fetus, and CNS/skeletal malformations

Question 11

What are the potential teratogenic effects of antihypertensive agents. Give two examples.

Answer 11

ACE inhibitors
ARBs

Associated with renal damage
May restrict normal growth patterns

Question 12

Give five possible fetotoxic effects of drugs

Answer 12

Growth retardation
Structural malformations
Fetal death
Functional impairment
Carcinogenesis

Question 13

Give seven drugs/classes of drugs that should be avoided during breast-feeding

Answer 13

• Cytotoxics
• Immunosuppressants
• Anti-convulsants (not all)
• Drugs of abuse
• Amiodarone
• Lithium
• Radio-iodine