drug distribution Flashcards
define drug distribution
transfer of drugs to tissues, drugs and blood compartments
is drug distribution reversible ?
yes transfer of drugs to blood compartments , tissues & organs is reversible
what effects/factors influencing drug distribution (5)
-blood flow
-capillary permeability
-solubility
-volume distribution
-protein binding
give an example of a membrane barrier affecting drug distribution
blood brain barrier
testes & ovary barrier
both contain tight junctions (affect capillary permeability)
what are plasma binding proteins?
albumins that bind to drugs making them biologically inactive
be familiar with what effects the level of bound drugs
hypoalbuminanemia
rectal failure
pregnancy
other drugs
what is filtered at the glomerulus
unbound drugs
what has an affect on glomerulus secretion of a drug
size and ionisation of the drug
How does filtration rate affect drug clearance rate?
increased filtration rate increases drug clearance rate
What does active tubular secretion mainly excrete?
protein bound cationic and anionic drugs
How happens to some of the drug in passive tubular filtraion?
Its reabsorbed by passive diffusion, only the unionised drug is reabsorbed
In passive tubular filtration how does drug conc change?
The further downt he kidney tubules the more concentrated the filtrate.
Therefore the drug is also more concentrated.
equation to calculate volume distribution of a drug
vd= bioavailibily x dose / conc
