Pharmacokinetics, Drug Metabolism, and Drug Disposition

Question 1

pharmacokinetics

Answer 1

the science of a drug’s fate in the body

Question 2

What are the 4 components that contribute to drug disposition?

Answer 2

absorption, distribution, metabolism, and excretion

Question 3

bioavailability

Answer 3

the rate and extent of drug absorption

Question 4

What is volume of distribution directly related to?

Answer 4

half-life

Question 5

half-life

Answer 5

the time required to eliminate half the drug from the body

Question 6

Approximately 50% of drugs undergo some form of hepatic metabolism

Answer 6

The primary purpose of hepatic metabolism is to increase a drug’s water solubility to facilitate its renal elimination

Question 7

The kidneys serve as the primary eliminating organ for drugs that do not undergo hepatic metabolism. Renal clearance comprises of three main physiologic processes:

Answer 7

glomerular filtration, reabsorption, and secretion

Question 8

filtration clearance

Answer 8

the product of drug not bound to protein and the glomerular filtration rate

Question 9

For IV drug input, the concentration is given by:

Answer 9

C=(Dose/V) x e^-(K x t)

C=concentration
K=elimination rate constant=Cl/V
Cl=clearance=Dose/AUC
V=volume

Question 10

For drugs that are administered extravascularly (PO, IM, or SC) and act systemically, absorption must occur. For first-order absorption, the concentration is given by:

Answer 10

C=(Ka x F x Dose/V x (Ka-K)) x (e^-(K x t) – x^-(Ka x t)

Ka=first-order rate constant for drug absorption
t1/2=0.693/Ka
K=first-order rate constant for drug elimination
Cl=F x Dose/AUC
Oral clearance=Cl/F=Dose/AUC
F=bioavailability or fraction of drug absorbed