Prescribing in pregnancy Flashcards

1
Q

What drugs cross the placenta?

A

Most drugs, except large molecular weight drugs e.g. heparin. Small, lipid-soluble drugs cross more quickly.

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2
Q

What may affect absorption of drugs?

A

Morning sickness

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3
Q

What may affect distribution in pregnancy?

A

Increased plasma volume and fat stores, volume of distribution increases.

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4
Q

What affects metabolism of drugs in pregnancy?

A

Decreased protein binding, increased free drug due to lower albumin levels.

Increased liver metabolism of some drugs.

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5
Q

What affects the elimination of drugs in pregnancy?

A

Renal excretion increases, increased GFR

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6
Q

What are the changes to pharmacodynamics in pregnancy?

A

No significant changes in pregnancy.

May be more sensitive to some drugs, hypotension with antihypertensives in 2nd trimester.

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7
Q

What should be given 3 months prior to conception and up to 3 months after conception?

A

Folic acid 400ug

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8
Q

What major process happens in first trimester?

A

Organogenesis

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9
Q

What is the period of greatest teratogenic risk?

A

4th-11th week

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10
Q

What general guidance should be given in 1st trimester of pregnancy?

A

avoid drugs if at all possible unless maternal benefit outweighs risk to foetus

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11
Q

What are the adverse affects of ACE inhibitors/ ARBs

A

Renal hypoplasia

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12
Q

What are the adverse affects of androgens

A

Virilisation of female foetus

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13
Q

What are the adverse affects of anti-epileptics

A

Cardiac, facial, limb, neural tube defects

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14
Q

What are the adverse affects of cytotoxics

A

Multiple defects, abortion

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15
Q

What are the adverse affects of lithium

A

Cardiovascular defects

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16
Q

What are the adverse affects of methotrexate

A

Skeletal defects

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17
Q

What are the adverse affects of retinoids

A

Ear, cardiovascular or skeletal defects

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18
Q

What are the adverse affects of warfarin

A

Limb and facial defects

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19
Q

What is the major process that can be impacted in the 2nd and 3rd trimester

A

Growth of foetus

Functional development; intellectual impairment and behavioural abnormalities

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20
Q

What are the adverse effects on labour?

A
  • progress of labour
  • adaptation of foetal circulation (premature closure of ductus arteriosus)
  • suppression of foetal systems (opiates- respiratory depression)
  • bleeding (warfarin)
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21
Q

What drugs can have adverse effects on baby after delivery?

A

Opiates, SSRI- withdrawal syndrome, sedation

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22
Q

What is linked to diethylstilbestrol?

A

Vaginal adenocarcinoma in girls aged 15-20 years whose mothers were exposed and urological malignancy in boys

23
Q

What causes increased seizures in pregnancy?

A
  • non-compliance

- changes in plasma concentration of drugs (persistent vomiting, increased clearance)

24
Q

What are frequent seizures during pregnancy are associated with?

A

lower verbal IQ in child, hypoxia, bradycardia, antenatal death, maternal death

25
Q

What do anti epileptics increase the risk of?

A

Congenital malformations

  • 20-30% risk if on 4 drugs
  • mono-therapy preferred
26
Q

Which AEDs should be avoided in pregnancy?

A

Valproate, phenytoin

27
Q

What should be given to women on AEDs?

A

Folic acid 5mg daily

28
Q

Describe the treatment of diabetes in pregnancy

A

Insulin is thought to be safe, sulfonylureas not safe

29
Q

What does poor diabetic control cause?

A

Increases risk of congenital malformations and intra-uterine death

30
Q

When does BP fall?

A

2nd trimester

31
Q

What should be used to treat hypertension in pregnancy?

A

Labetalol
Methyldopa
Nifedipine

32
Q

What medication- used for hypertension- should be avoided?

A

ACE inhibitors ARB

BB- may inhibit foetal growth in late pregnancy

33
Q

What should be used for nausea and vomiting in pregnancy?

A

Cyclizine

34
Q

What should be used for UTI in pregnancy?

A

Nitrofurantoin, cefalexin (3rd trimester- trimethoprim)

35
Q

What should be used for pain in pregnancy?

A

Paracetamol

36
Q

What should be used for heartburn in pregnancy?

A

Antacids

37
Q

What is the risk of VTE in pregnancy vs non pregnancy?

A

10 fold

38
Q

What is the leading cause of maternal death in pregnancy?

A

VTE

39
Q

What should women be encouraged to do to prevent VTE?

A

Mobilise and be adequately hydrated

40
Q

What should those with significant VTE risks be given?

A

LMWH at delivery and up to 7 days post partum

41
Q

How should a suspected or established DVT or PE be treated in pregnancy?

A

low dose LMWH

42
Q

Which drugs enter breast milk?

A

Most drugs, especially small molecules, fat soluble (lipophilic drugs)

43
Q

How do feeding patterns affect amounts of drug in breast milk?

A
  • foremilk - rich protein
  • hindmilk- higher fat content
  • longer feeds- higher amount of fat-soluble drugs in milk
44
Q

What drugs are actively concentrated in breast milk?

A

Phenobarbitone- suckling difficulties

45
Q

What problems are caused by amiodarone?

A

Neonatal hypothyroidism

46
Q

What problems are caused by cytotoxics?

A

bone marrow suppression

47
Q

What problems are caused by benzodiazepines?

A

Drowsiness

48
Q

What problems are caused by bromocriptine?

A

Suppress lactation

49
Q

What drug causes staining of bones and teeth?

A

Tetracycline, avoid in children up to 12 y/o

50
Q

What are the discriminating features of foetal alcohol syndrome?

A
Short palpebral fissures
Flat midface
Short nose
Indistinct philtrum
Thin upper lip
51
Q

What are the associated features of foetal alcohol syndrome?

A
  • Epicanthal fold- skin of upper eyelid that covers the inner corner of the eye
  • low nasal bridge
  • minor ear abnormalities
  • micrognathia
52
Q

What is micrognathia?

A

Undersized jaw

53
Q

What is caused by phenytoin

A

Cleft lip and palate

54
Q

What is caused by valproate?

A

Neural tube defects

Spina bifida and anencephaly