Block I - Kinetics - E

Question 1

How does pH affect elimination of drugs

Answer 1

Normally drugs can be eliminated in kidneys via phase 1 and 2 reactions. However, ion trapping refers to the altering of urine pH to eliminate drugs. Basic drugs eliminated by alkalizing urine; acidic drugs eliminated by acidification.

Question 2

Half-life

Answer 2

Time it takes to reduce plasma drug concentration by half

Question 3

Steady state

Answer 3

Reached after 4-5 half-lives

Question 4

Differences in half-life

Answer 4

Higher half-life takes longer to clear; lower half-life takes less time to clear

Question 5

Duration of action

Answer 5

Amount of time drug concentration is within therapeutic range

Question 6

Clearance

Answer 6

Composite estimate of amount of drug cleared from body per unit time (metabolism or elimination)

Question 7

Calculate half-life knowing steady state

Answer 7

t(SS) = 4-5 x t(1/2)

Question 8

Cockroft and Gault equation

Answer 8

Creatinine clearance = (140 - age) x weight (kg) (x 0.85 for women)

Question 9

Therapeutic range

Answer 9

Concentration of drug which most patient experience desired clinical effect with minimum adverse reactions.

Question 10

Therapeutic index/window

Answer 10

Ratio of dose that produces toxicity to dose that produces clinically desired or effective response (TI = TD50/ED50)