Pharmacology in Pregnancy and Breast Feeding Flashcards
1
Q
How does pregnancy affect drug absorbtion?
A
- oral route
- morning sickness
- inc. gastric emptying + gut motility
- IM route
- inc. blood flow ∴ inc. absorbtion
- inhalation
- inc. CO + dec. tidal V ∴ inc. absorbtion
2
Q
How does pregnancy affect drug distribution?
A
- inc. plasma V + fat will change distribution ∴ inc. Vd
- inc. plasma dilution will dec. relative amount of plasma proteins ∴ inc. fraction of free drug
3
Q
How does pregnancy affect drug metabolism?
A
- oestrogen and progesterone can induce or inhibit liver P450 enzymes ∴ inc. or dec. metabolism
4
Q
How does pregnancy affect drug excretion?
A
- GFR inc. by 50% ∴ inc. in most drug’s excretion ∴ dec. plasma concentration
5
Q
How does pregnancy affect drug pharmacodynamics?
A
- may affect site of action + receptor response to drug
- may affect efficacy
- adverse effects may be different
* pharmacodynamics in pregnancy less well understood
6
Q
Drugs can by passed from mother to fetus, what affects placental transfer?
A
- molecular weight (smaller molecules will pass more easily)
- polarity (non-polar molecules will pass more easily)
- lipid solubility (lipid soluble drugs will pass)
- placenta may also metabolise some drugs
7
Q
What is different about fetal drug distribution?
A
- circulation different
- less protein binding ∴ more free drug
- little fat ∴ distribution different
- relatively more blood flow to brain
8
Q
What is different about fetal drug metabolism?
A
- less enzyme activity (but inc. during gestation)
- different isoenzymes to adults
9
Q
What is different about fetal drug excretion?
A
- excretion is into amniotic sac- can be swallowed and recirculated
- drug and metabolites can accumulate in amniotic fluid
- placenta not functioning at delivery so can cause excretory issues
10
Q
What mechanisms caused by a teratogen, can cause a fetal abnormaility?
A
- folate antagonism
- block conversion of folate to THF by binding irreversibly to enzyme (methotrexate, trimethoprim)
- block other ezymes in the pathway (phyenytoin, carbamazepine, valproate)
- usually; neural tube, oro-facial or limb defects
- neural crest cell disruption
- retinoid drugs (isotretinoin)
- usually affects; aortic arch, ventricular septal, craniofacial, pharyngeal gland, oesophageal atresia
- endocrine disruption: sex hormones
- oxidative stress
- vascular disruption
- specific receptor/enzyme mediated teratogenesis
- may affect fetal enzymes + receptors
- orofacial clefts, cardiac septal defects (NSAIDs)
11
Q
What is fetotoxicity and what can it cause?
A
- damage to the fetus later in pregnancy
- growth retardation
- structural malformations
- fetal death
- functional impairment
- carcinogenesis
- ACE inhibitors/ARBs- renal dysfunction + growth retardation
12
Q
What drugs should be avoided when breast feeding?
A
- cytotoxics
- immunosuppressants
- some anti-convulsants
- drugs of abuse
- amiodarone
- litium
- radio-iodine
