Distribution

Question 1

What is distribution

Answer 1

Getting drug to site of action

Question 2

What effects distribution (5)

Answer 2

1. Protein binding
2. Blood flow
3. Membrane permeation ( lipid solubility)
4. Tissue solubility ( pH and ionisation)
5. Molecular size

Question 3

Do plasma protein bound drugs excerpt action ?

Answer 3

No - only free drug

Question 4

What can effect patients plasma proteins? (2)

Answer 4

Liver failure or kidney damage

NB plasma proteins made in liver

Question 5

What is volume distribution?

Answer 5

How far drug travels

Lipophilic - large Vd
Water sol - small Vd

Question 6

What is the acid dissociation constant pKa?

Answer 6

Strength of an acid
pH when 50% of drug molecules are ionised

Question 7

Do lipids attract non ionised molecules?

Answer 7

Yes

Question 8

Do aqueous sols attract ionised mols

Answer 8

Yes

Question 9

Acidic drugs in acidic environments will be?

Answer 9

Non ionised ( move through lipid membranes)

Question 10

Alkali drugs in alkaline solutions will be ?

Answer 10

Non ionised- move though lipid membrane

Question 11

Acidic drugs in alkaline environments and alkaline drugs in acidic environments will be

Answer 11

Ionised ( will not move through lipid membranes

Question 12

What effects drug distribution? ( 5)

Answer 12

1. Drugs needs to cross cell membrane to produce effects
2. Degree of ionisation (low better)
3. Molecular weight ( low better)
4. Lipid solubility ( high better)
5. Concentration gradient ( high better)