Therapeutics in Pregnancy Flashcards
do the pharmacokinetics of drugs change during pregnancy
yes
pharmacokinetics changes of drugs during pregnancy widely includes
- absorption: oral; IM/SC/transdermal
- distribution
- metabolism
- excretion: renal; hepatobiliary
(ADME)
oral absorption has what pharmacokinetic change in pregnancy
tends to decrease
why does oral absorption tend to decrease as a pharmacokinetic change in pregnancy
- delayed gastric emptying due to progesterone (smooth muscle relaxant)
- reduction in gut motility due to physical effect of uterus
- decreased gastric acid production-> increases gut pH -> variable effects on drug absorption
- nausea and vomiting that may occur from morning sickness
how is oral absorption decrease attenuated in some cases
increases in gastrointestinal blood flow
why does IM/SC/transdermal absorption tend to increase as a pharmacokinetic change in pregnancy
- there is increased regional blood flow
IM/SC/transdermal absorption has what pharmacokinetic change in pregnancy
tends to increase
some significant changes in distribution that occur during pregnancy result in which - decreased or increased volume of distribution of drugs?
increased volume of distribution
what do the increased distributions of volume affect in medication administration
in general, greater dosage of drug required to achieve a therapeutic effect
what happens to total plasma volume throughout pregnancy
- increases
- increased total body water (increase total plasma volume)
-> affects serum protein
what drugs does increased body fat from pregnancy increase the volume of distribution for
lipophilic drugs
describe how can increase unbound fraction of medications -> greater therapeutic effect for a given dose in some medications
- decreased serum protein (dilutional)
- serum proteins bind drugs in bloodstream => more free drug in bloodstream
- can result in greater therapeutic effect for a given dose in pregnant vs non pregnant
what is volume of distribution in pharmacokinetics
distribution of a drug within the body relative to its concentration in the bloodstream
drug distributes more extensively throughout the body beyond the bloodstream. It suggests that the drug is distributed into tissues and organs beyond the bloodstream
more widely distributed within the body’s compartments
what changes in pregnancy lead to decreased serum protein
- serum protein is protein levels in blood serum
- during pregnancy plasma volume increases which has diluting effect on serum protein
how does metabolism of drug change during pregnancy
drug clearance may be increased or decreased based on the particular metabolic pathway
during pregnancy what happens to hepatic (liver) enzymes, which can have an effect on drug metabolism
- activity of hepatic (liver) enzymes can be either inhibited or induced by pregnancy hormones (eg/ progesterone - induce; oestrogen - inhibit)
-> variable effects, highly dependent on genetics
during pregnancy does hepatic blood flow change and can this have an effect on drug metabolism
- changes
- which can affect hepatic clearance of some drugs
during pregnancy there is significant increase in ___ excretion
renal excretion
why is there an increase in renal excretion during pregnancy
- GFR increases during pregnancy
why does GFR increase during pregnancy
mainly due to increase in cardiac output during pregnancy
what would increase renal excretion in pregnancy have a significant imapct on
renally cleared drugs
what does the concomitant increase of tubular resorption in pregnancy result in
- unpredictable effects on renal clearance of some drugs
what is the relevance of the unpredictable effects of increased tubular resorption on renal clearance of some drugs
renal clearance not always directly proportional to renal changes in GFR
in general, does renal excretion of drugs in pregnancy decrease or increase
increase
