Pharmacology in Pregnancy

Question 1

What may be the issues when giving a PO medication during pregnancy ?

Answer 1

Morning sickness.

Decrease in gastric emptying and gut motility.

Question 2

What may be the issues when giving an IM medication during pregnancy ?

Answer 2

Blood flow may be increased therefore absorption may also increase using this route.

Question 3

What may be the issues when giving an inhaled medication during pregnancy ?

Answer 3

Increased cardiac output and decreased tidal volume may cause increased absorption of inhaled drugs.

Question 4

How will the distribution of drug change in pregnancy ?

Answer 4

Increase in plasma volume and fat will change distribution of drug.
Greater dilution of plasma will decrease relative amount of plasma proteins - increases the fraction of free drug.

Question 5

How will metabolism of drugs in pregnancy change ?

Answer 5

Oestrogen and progesterone can induce or inhibit liver P450 enzymes, increasing or reducing metabolism.

Question 6

How will the excretion of drugs change during pregnancy ?

Answer 6

GFR increased - increased excretion of drugs.

Reduce plasma concentration. - can necessitate an increase in dose of renally cleared drugs.

Question 7

What are the 3 main functions of the placenta ?

Answer 7

1. Attach the foetus of the uterine wall.
2. Provide nutrients to the foetus.
3. Allow the foetus to transfer waste products to the mothers blood.

Question 8

Placental transfer depends on what ?

Answer 8

Molecular weight (smaller sizes cross more easily)
Polarity (non-polar cross more readily)

Question 9

What makes a drug more likely to cross the placenta ?

Answer 9

Low molecular weight <500Da

Non-ionized drugs cross the placenta more easily than ionized drugs.

High lipophilicity will increase placental transfer.

Question 10

What occurs when a foetus excretes a drug ?

Answer 10

Excretion into the amniotic fluid - swallowed and can allow re-circulation.

Drugs and metabolites can accumulate in the amniotic fluid.

Question 11

Between which weeks is the biggest risk to organogenesis of the foetus ?

Answer 11

Weeks 3-8

Question 12

What kinds of mechanisms occur during distorted organogenesis ?

Answer 12

Folate antagonism - Forming new DNA which can result in neural tube defects.

Neural crest cell disruption - Aortic arch abnormalities, esophageal atresia and pharyngeal gland abnormalities.

Oxidative stress

Vascular disruption.

Question 13

What kind of toxic effect can drugs have on the foetus later in pregnancy ?

Answer 13

Growth retardation
Structural malformations
Foetal death
Functional impairment
Carcinogenesis

Question 14

Give some examples of of drugs which cause Fetotoxicity

Answer 14

Ace inhibitors

ARBs

Question 15

Name 6 known teratogens to avoid during pregnancy

Answer 15

Anticonvulsants
Anticoagulants
Antihypertensive agents
NSAIDs
Alcohol
Retinoids

Question 16

What kind of teratogenic effects does anticonvulsants have on the foetus ?

Answer 16

Valproate - neural tube defects

Question 17

What kind of teratogenic effects does anticoagulants have on the foetus ?

Answer 17

Warfarin associated with hemorrhage as well as malformations in the CNS and skeletal system

Question 18

What kind of teratogenic effects does anti-hypertansives have on the foetus ?

Answer 18

ACEi cause renal damage and may restrict normal growth

Question 19

What kind of teratogenic effects do NSAIDs have on the foetus ?

Answer 19

Premature closure of the ductus arteriosus

Question 20

What kind of teratogenic effects does alcohol have on the foetus ?

Answer 20

Fetal alcohol syndrome

Question 21

What kind of teratogenic effects do retinoids have on the foetus ?

Answer 21

Ear, CNS, CVS ad skeletal disorders.

Question 22

Name some drugs to avoid during breast feeding

Answer 22

Cytotoxic drugs 
Immunosuppressants
Anti-convulsant 
Drugs of abuse
Amiodarone
Lithium 
Radio-iodine