pharmacology

Question 1

what does Clearance determine?

Answer 1

the maintenance dose required to achieve the desired steady-state concentration

Question 2

What does the volume of distribution determine?

Answer 2

the loading dose required to achieve the desired steady-state concentration

Question 3

What does the half-life determine?

Answer 3

the time to reach steady-state, and the dosage interval

Question 4

Clearance is a function of what?

Answer 4

clearance is a function of the blood flow to clearing organs and the efficiency of the organ in extracting the drug

Question 5

Volume of distribution is a function of what?

Answer 5

Vd is a function of the physiologic volume of blood and tissues and how the drug binds in blood and tissues

Question 6

What is half-life depended on?

Answer 6

the T1/2 is dependent on the value of volume distribution (high Vd = high T1/2) and on the value of clearance (high clearance= decreased T1/2)

Question 7

Describe linear (first order) kinetics

Answer 7

in first order kinetics, drug serum concentration will decrease in a straight line when plotted on a log concentration-time graph. also, steady-state drug serum concentrations change proportionally to dose

Question 8

Describe Non-linear (zero order) kinetics

Answer 8

in zero order kinetics, drug concentration exceeds the elimination rate constant. the steady-state drug serum concentrations change non-proportionally to dose. the mass of the drug eliminated will stay the same (not percentage)

Question 9

What type of kinetics do most drugs follow?

Answer 9

linear (first order) kinetics

Question 10

What enzyme system is responsible for the metabolism of most drugs?

Answer 10

cytochrome P450

Question 11

if pharmocologic effect is pltotted against drug concentration for most agents, what is the shape of the graph?

Answer 11

hyperbolic (sigmoidal)

Question 12

what does the time required to reach Css depend upon (drug follows first order)?

Answer 12

dose, half-life, bioavailability, and compliance

Question 13

does the volume of distribution vary with time and plasma drug concentration?

Answer 13

no Vd is constant (presence of disease can effect Vd)

Question 14

does T1/2 of elimination of drug vary inversely with the elimination rate and the volume of distribution?

Answer 14

NO,

T1/2 is proportional to Vd and inversely proportional Kel

Question 15

pH< PKa
acid -> HA
base B+

Answer 15

weak base will become protonated (ionized) and thus be unable to be absorbed but rather will be excreted
acid is unprotonated and will be able to pass through membranes

Question 16

pH> Pka
acid-> A-
base -> B

Answer 16

weak acid will be ionized and thus trapped (not able to pass so it will be excreted)
weak base is unionized and will be able to pass through membrane