3: Drug elimination

Question 1

What is the minimum effective concentration (MEC) of a drug?

Answer 1

The minimum conc. of a drug required to achieve an effect

Question 2

What is the maximum tolerated concentration (MTC) of a drug?

Answer 2

Maximum conc. of a drug tolerated before you get significant unwanted effects

Question 3

What is the therapeutic window?

Answer 3

Range of concentrations of drug which is safe

Question 4

How do you calculate the therapeutic ratio of a drug?

Answer 4

MTC / MEC

Question 5

What is suggested about drugs with a high therapeutic ratio?

Answer 5

Safer

Question 6

What is suggested about drugs with a low therapeutic ratio?

Answer 6

Unsafe

Question 7

For most drugs, rate of elimination is directly proportional to what?

Answer 7

Drug concentration

Question 8

What is the half life of a drug?

Answer 8

Time taken for drug concentration to decrease by 50%

Question 9

What equation can be used to calculate half life using rate of elimination?

Answer 9

t_1/2 = 0.69/K_el

Question 10

For first order drugs, does the initial dose affect K_el or t_1/2?

Answer 10

No

Question 11

What is clearance?

Answer 11

The volume of plasma cleared of drug per unit time

Question 12

In IV administration, no matter the initial infusion rate, how long does it take to reach a constant concentration of drug?

Answer 12

5 HALF LIVES

Question 13

What is a loading dose?

Answer 13

Initial higher dose of drug given at the start of a course of treatment

Brings patient to steady state quicker

Question 14

What two variables is half life dependent on?

Answer 14

Volume of distribution of the drug

Clearance of the drug