Distribution

Question 1

what are the compartments for distribution?

Answer 1

plasma, extracellular interstitial fluid, intracellular fluid, transcellular fluid

Question 2

which factors influence distribution?

Answer 2

• permeability across tissue barriers
• binding wishing compartments
• pH partition
• Fat:water partition

Question 3

in our bodies drugs are in bound form or free form

Answer 3

bound form inactive – free form metabolised and extorted

equilibruim

Question 4

how are the CNS and the brian protected from drugs/spread?

Answer 4

continuous layer of endothelial cells with tight junctions

Question 5

how may the tight junctions in the endothelia be disrupted in the CNS?

Answer 5

inflammation

white blood cells and some small molecules can then pass

Question 6

why will pass the BBB?

Answer 6

water, some lipid soluble molecules (small) and glucose

Question 7

what size of molecules can pass through the BBB

Answer 7

smaller than 5000 dalton

Question 8

why do the brain and muscle equilibrate quickly (if the substance crosses the BBB)

Answer 8

because they are highly vasularised

Question 9

fat takes long time to equilibrate, why?

Answer 9

low vascularisation

Question 10

what is the volume of distribution?

Answer 10

the theoretical volume that would be necessary to contain the total of administered drug (Q) at the same conc. that is observed in the plasma (Cp)

Question 11

which factors that are related to the drug affect distribution?

Answer 11

Lipid solubility 
Molecular size 
Degree of ionisation
Cellular binding
Duration of action
Therapeutic effects
Toxic effects

Question 12

which factors that are related to the body affect distribution?

Answer 12

Vascularity
Transport mechanisms
Blood/Placental barriers
Free and bound forms of drugs
Drug interaction
Drug reservoirs
Plasma binding proteins

Question 13

protein + drug equilibrates with

Answer 13

protein drug compelx

Question 14

plasma proteins can bind drugs to keep them in

Answer 14

an inactive form

Question 15

in the plasma what does the protein albumin mainly bind to?

Answer 15

acidic and neutral drugs

Question 16

in the plasma what does HSA normally bind to?

Answer 16

acidic and neutral drugs

Question 17

in the plasma what does A1A normally bind to?

Answer 17

basic drugs

Question 18

which drugs extensively bind to plasma proteins/

Answer 18

warren, statins, naproxen, diclophenac, naladixic acid

Question 19

which drug barely bind to plasma proteins in the blood?

Answer 19

ahminoglycosides, fluconozole, codeine, lithium, ethanol

Question 20

which are the major compartments of the body for distribution and what are their %?

Answer 20

• plasma (5%)
• interstitial fluid (16%)
• intracellular fluid (35%)
• transcellular fluid (2%)
• fat (20%)

Question 21

define volume of distribution (Vd)

Answer 21

the volume of plasma that would contain the total body content of the drug at a concentration equal to that in the plasma

Question 22

lipid in-soluble drugs are mainly confined to

Answer 22

the plasma and interstitial fluids, and do not enter the brain following acute dosing

Question 23

lipid soluble drugs reach all (a) and may accumulate in (b)

Answer 23

a - compartments

b - fat

Question 24

for drugs that accumulate outside the plasma compartments, Vd may

Answer 24

exceed total body volume