Distribution

Question 1

What is Vd?

Answer 1

The volume of distribution is a theoretical proportionality factor that relates the amount of a drug in the body to the concentration measured in the blood plasma.

Question 2

What has a higher Vd- lipophilic or hydrophilic drugs?

Answer 2

Lipophilic drugs have a higher Vd because there is a lower concentration stored in the blood plasma compartment.

Question 3

A very hydrophilic drug would have what relative absorption and excretion?

Answer 3

Pass the liver and kidneys more often so excreted faster (short half-life)

Not easily absorbed into tissues.

Question 4

What is the CMax?

Answer 4

The peak concentration of a drug in a compartment after administration.

Question 5

What would dehydration do to the Vd of a drug?

Answer 5

Lower amount of fluid in blood plasma = higher concentration of drug = lower Vd

Question 6

What type of drug might have a Vd > 42L?

Answer 6

Lipophilic

Question 7

What properties must a drug have to lipophilic?

Answer 7

Uncharged and non-polar

Question 8

What is the first-pass effect?

Answer 8

Oral drugs are taken via the liver, if they are easily metabolised here then the availability to the body will be severely decreased by the first pass effect.

Question 9

What type of drug might have a Vd of <5L?

Answer 9

Hydrophilic

Question 10

The half-life of a lipophilic drug is what in compared with a hydrophilic drug?

Answer 10

t 1/2 is increased

Question 11

Drugs with good protein binding are primarily kept in what compartment?

Answer 11

Plasma

Question 12

What happens to drug clearance via the liver and kidneys with age? What effect does this have on drug availability? What does this often mean for dosages in practice?

Answer 12

Metabolism and excretion decreases. Increasing half-life and availability to the tissues. Increasing drug affect.
Generally, dosages should be decreased in the elderly.

Question 13

Their is an increased variability in renal clearance in older age groups, what does this mean?

Answer 13

Some of that age group will have a good renal clearance and some will have a very poor renal clearance. This means that a drug can have a significantly different effect on two people in the same age group.

Question 14

What effect does plasma protein binding have on clearance and half-life of a drug?

Answer 14

Drugs that are bound to proteins aren’t able to be cleared or metabolised. So they have decreased clearance and a longer half-life.

Question 15

A drug with greater plasma protein binding has what Vd?

Answer 15

Lower