Distribution Flashcards
Distribution is
When drugs leave blood and enter extravasc. fluids and tissues
Rate limiting step in distribution is
Blood flow
What are the organs that receive rapidly high levels of drugs
- highly perfused
- i.e. liver, kidney, GIT, brain, lungs
Which organs receive lower levels of drugs
- less perfused organs
- bone, muscle, fat
Increase in plasma protein binding does what to distribution efficiency
Decreases it and its potency
Acidic drugs bind to
Albumin
When more than 70-80% of a drug is bound to plasma protein, the plasma protein acts as a…
Circulating reservoir
Heavily protein-bound drugs have what kind of plasma half-lives
Longer
If a drug is heavily protein bound, then
- has narrow therapeutic index
- small vol. of distribution
- possible toxicity and biological activity of drug increase
Basic drugs bind to
Alpha 1-acid glycoprotein
Effedcts of plasma-protein binding on drug
- slows rate at which drug reaches a conc. sufficient enough to produce pharm. effect
- limits glomerular function
Bleeding syndrome
When albumin binds to aspirin instead of warfarin, causing free warfarin to move around in blood
Barriers to drug dist.
- BBB
- Placenta
- Milk
BBB as durg barrier
- doesn’t let ionized and non-lipid soluble drugs pass
- lack fenestrations
- MDR1 causes more tight junctions
Placenta as drug barrier
- technically not a barrier
- highly ionized drugs, low lipid soluble drugs excluded
- teratogenic drugs
