Pharmacokinetics

Question 1

Define PK

Answer 1

what the human body does to a drug

Question 2

Define PD

Answer 2

what the drug does to the human body

Question 3

Define enterohepatic recycling

Answer 3

drugs are transported through the bile from the liver back to the gut where they can be reabsorbed

Question 4

Define bioavailability

Answer 4

extent to which a drug is absorbed into the systemic circulation

Question 5

Corrected Ca equation

Answer 5

Ca + [(4-albumin) x 0.8]

Question 6

Free phenytoin equation

Answer 6

total phenytoin measured/ (0.2 x albumin) +0.1

Question 7

Define volume of distribution

Answer 7

how large an area in the patient’s body the drug has dristributed into, and is based on the properties of the drug

Question 8

Vd calculation

Answer 8

amount of drug in body/concentration of drug in plasma

Question 9

Define first-pass metabolism

Answer 9

hepatic metabolism of a drug before it reaches the systemic circulation, which can dramatically reduce the bioavailability of an oral formulation

Question 10

Clearance equation

Answer 10

rate of elimination (Re)/ concentration

Question 11

which drugs don’t follow first order kinetics

Answer 11

phenytoin
theophylline
voriconazole

Question 12

Define elimination rate constant

Answer 12

is the fraction of the drug that is eliminated per unit of time

Question 13

Elimination rate constant equation

Answer 13

ke = Cl/Vd

Question 14

Define half-life

Answer 14

the time required for the drug concentration to decrease by 50%

Question 15

half-life equation

Answer 15

t1/2 = 0.693/ke

Question 16

how many half-lives does it take to reach steady state

Answer 16

5

Question 17

Loading dose equation

Answer 17

Ld = desired concentration x Vd/ F