Pharmacology in Pregnancy and Breast feeding Flashcards
1
Q
Introduction
A
- Majority of women take medication during pregnancy
- Many pregnancies will be unplanned
- Must consider effect of pregnancy when prescribing to any women of childbearing age
2
Q
Why are medications used during pregnancies
A
- Hypertension
- Asthma
- Epilespy
- Mental health issue
- Migraines
- Long-term anticoagulant therapy
3
Q
Why is pharmacology during pregnancy so complex
A
- Very little pharmacokinetic studies of medicaitons during pregnancy
- Datae is limited
4
Q
Absorption changes during pregnancy
A
- Oral route
- Morning sickness causing nausea/ vomitting
- Decreased gastric emptying and gut motility (more likely to affect single dose medications)
- IM and SC route -> increased blood flow, increased absorption of medications
- Inhalation -> increased cardiac output and tidal volume, increased absoprtion of medications
5
Q
Distribution changes during pregnancy
A
- Increased volume of distribution due to:
- Increased plasma volume
- Increased fat composition
- Increased fraction of unbound drugs in plasma
- Greater proportion of plasma to plasma protein
- More dilution
6
Q
Metabolism changes in pregancy
A
- Oestrogen and progestrogen can alter P450 liver enzme
- Causes changes in metabolism
- E.g
- Phenytoin levels reduced, metabolism increases
- Theophylline levels increase, metabolism decreases
7
Q
Excretory changes
A
- Increased GFR by 50% during pregnancy
- Increased excretion of medications
- Reduced plasma concentration of medications
- Therapeutic levels of medications require an increased dose
8
Q
Pharmacokinetics vs pharmacodynamics
A
- Pharmacokinetics (what the body does to the drug)
- Pharmacodynamics (what the drug does to the body)
9
Q
Pharmacodynamic changes in prgenancy
A
- Affects site of action and response of receptor to drug
- Concentration of the drug
- Presence of metabolites at site
- Changes to the receptor
- Changes in efficacy
- Less understood and can have different adverse reactions
10
Q
Factors affecting drug tranfer across placenta
A
- Properties of the drug
- Rate of drug tranfer across placenta and amount reaching fetus
- Duration of exposure
- Distribution in fetal tissue
- Stage of placental and fetal development
- Combination effects of drugs
11
Q
Factors affecting placental transfer of medications
A
- Molecular weight og medicaitons
- Polarity
- Lipid solubility
- Placental metabolism of medication
- Assume all medications can cross placenta**
12
Q
Distribution of medications in fetus
A
- Different circulatory system (umbilical vein -> liver)
- Less plasma protein to adults (more free drug available)
- Little fat (less lipid distribution of medications)
- More bloodflow to brain
13
Q
Metabolism of medications in fetus
A
- Different P450 enzyme to adults (isoenzyme)
- Reduce enzyme activity (increases with gestation)
14
Q
- Excretion of medicaitons in fetus
A
- Fetal excretion into amniotic fluid -> swallowed then recirculated
- Drugs/ metabolites accummulate in amniotic fluid
- Non-functioning placenta during delivery (causes
15
Q
Teratotoxicity vs fetotoxicity
A
- Teratotoxicity (fiest trimester)
- Fetotoxicity (second and third trinemester)
