Pharmacology in pregnancy and breastfeeding Flashcards

1
Q

What are the physiological changes in pregnancy that alter drug absorption orally?

A

More difficult due to morning sickness

Decrease in gastric emptying and gut motility

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2
Q

What are the physiological changes in pregnancy that alter drug absorption IM?

A

Increased blood flow, so may increase absorption

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3
Q

What are the physiological changes in pregnancy that alter drug absorption via inhalation?

A

Increase CO and increased tidal volume may increase

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4
Q

What are the physiological changes in pregnancy that alter drug distribution?

A

Increase in plasma volume- greater dilution decreases relative amount of plasma proteins
Increase in fat

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5
Q

What are the physiological changes in pregnancy that alter drug metabolism and elimination?

A

Increased oestrogen and progesterone can induce or inhibit liver P450 enzymes

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6
Q

What are the physiological changes in pregnancy that alter drug excretion?

A

GFR increased

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7
Q

What is the overall effect of pregnancy on oral drug absorption, metabolism and excretion?

A

Absorption decreases
Metabolism increases
Excretion increases

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8
Q

What are the pharmacodynamic changes in pregnancy?

A

Changes in blood flow alter conc of drug and metabolites at site
Changes in receptors alters mechanism of action

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9
Q

What does placental transfer of drugs depend on?

A

Molecular weight- small sizes cross more easily
Polarity- non polar cross more easily
Lipid soluble cross more easily

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10
Q

What is the effect of the placenta on drugs?

A

Placenta will metabolise some drugs but assume all drugs will cross placenta

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11
Q

What ar the aspects to consider with drug distribution in a foetus?

A

Abnormal circulation
Less protein binding
Little fat
Relatively more flow to brain

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12
Q

What are the aspects to consider wth drug metabolism in a foetus?

A

Less enzyme activity

Different isoenzyme to adult

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13
Q

What are the aspects to consider with drug excretion in a foetus?

A

Excreted into amniotic fluid and can be swallowed and reabsorbed

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14
Q

What are the 2 forms of toxicity in pregnancy?

A

Teratogenicity- first trimester

Fetotoxicity- 2nd and 3rd trimesters

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15
Q

When is teratogenicity the biggest risk?

A

During organogenesis

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16
Q

What are the mechanisms of teratogenicity?

A
Folate antagonism
Neural crest cell disruption
Endocrine disruption
Oxidative stress
Vascular disruption
Specific receptor or enzyme mediated teratogenesis
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17
Q

What are the 2 methods by which drugs can cause folate antagonism?

A

Block conversion of folate to THF by binding irreversibly to the enzyme
Block other enzymes in the pathway

18
Q

What drugs can cause folate antagonism by blocking conversion of late?

A

Methotrexate, trimethoprim

19
Q

What drugs can cause folate antagonism by blocking other enzymes?

A

Phenytoin
Carbamazepine
Valproate

20
Q

What are the causative drugs of neural creat disruption?

A

Retinoids

21
Q

What problems can neural creat cell disruption cause?

A
Aortic arch abnormalities
Ventricular septal defect
Craniofacial malformation
Oesophageal atresia
Pharyngeal gland abnormalities
22
Q

What is enzyme mediated teratogenesis?

A

Drugs which inhibit or stimulate enzymes o produce therapeutic effects may also interact with specific receptors and enzymes, damaging foetal development

23
Q

What is an example of enzyme mediated teratogenesis?

A

NSAIDs can cause orofacial and cardiac septal defects

24
Q

What are the issues associated with fetotoxicity?

A
Growth retardation
Structural malformations
Foetal death
Functional impairment
Carcinogenesis
25
Q

What are the 5 categories of a drugs fetotoxicity?

A
A
B
C
D
X
26
Q

What are class A fetotoxic drugs?

A

Contolled human studies show no foetal risk

27
Q

What are class B fetotoxic drugs?

A

Animal studies show no foetal risk but no controlled human studies OR
Animal studies show a risk but controlled human studies did not

28
Q

What are class C fetotoxic drugs?

A

No adequate animal or human studies have been conducted OR

Adverse effects n animal study but no human data

29
Q

What are class D fetotoxic drugs?

A

Evidence of foetal risk exists but rbenefit may outweigh risk in certain circumstances

30
Q

What are class X fetotoxic drugs?

A

Proven foetal risks outweigh any benefit

31
Q

What classes of drugs are known teratogens?

A
Anticonvulsants
Anticoagulents
Antihypertensives
NSAIDs
Alcohol
Retinoids
32
Q

What are anticonvulsants associated with?

A

Valproate, carbamazepine ad phenytoin are associated with neural tube defects

33
Q

What are anticoagulants associated with?

A

Warfarin- haemorrhage in foetus and malformations of CNS and skeletal system

34
Q

What are antihypertensives associated with?

A

ACEi cause renal damage and restrict growth patterns

35
Q

What are NSAIDs associated with?

A

Premature closure of ductus arteriosus

36
Q

What is alcohol associated wth?

A

Foetal alcohol syndrome

37
Q

What are retinoids associated with?

A

Ear, CNS, CV and skeletal deformities

38
Q

What drugs should be avoided during lactation?

A
Cytotoxics
Immunosuppressants
Most, but not all, anticonvulsants
Drugs of abuse
Amiodaone
Lithium
Radio-iodine
39
Q

What are the principles of prescribing in non pregnant women of child bearing age?

A

Always consider pregnancy
Warn of possible risks
When treating long term conditions, advise women to attend when planning a pregnancy
If necessary, do not prescribe without contraception

40
Q

What are the principles of prescribing in pregnant women?

A

Try non pharm treatment firs where appropriate
Use drug with best safety record
Use lowest effective dose for shortest time possible, intermittently if at all possible
Avoid in 1st 10 weeks if possible
Don’t under treat disease

41
Q

What are the principles of prescribing in breastfeeding?

A

Avoid unnecessary drugs
If safe for paediatric use, esp in under 2s, usually safe to give
Choose drugs with pharmacokinetic properties that reduce infant exposure