Pharmacokinetics 2

Question 1

What is clearance?

Answer 1

Volume of plasma irreversibly cleared of drug per unit time

Question 2

Is clearance dependent on the volume of distribution?

Answer 2

No, however volume of distribution will influence the time take to reach steady state or to remove all drug from the body
A greater volume takes longer to reach steady state or empty

Question 3

How can the decline of drug concentration with time curve be converted to a straight line?

Answer 3

Graph the natural log of the initial concentration - (CL/V)*time
This results in a line that has a slope equal to CL/V

Question 4

What is a half-life?

Answer 4

The time required for the concentration of a drug in a plasma to be reduced by one half of its original value

Question 5

What factors influence the half-life of a drug?

Answer 5

The volume of distribution as an increase in volume the half life increases
The clearance as if this value increases then half-life decreases

Question 6

What is the formula used to work out half-life?

Answer 6

Half-Life= 0.7*V/CL

Question 7

What is the effect of infusing and repetitive dosing?

Answer 7

Accumulation of a drug occurs if the dose rate in is greater than the elimination rate
A stable state will be achieved if the dose rate in is equal to the elimination rate

Question 8

How long does it typically take to achieve steady state with repetitive dosing?

Answer 8

4 half-lives