Principles of Drug Action

Question 1

Some consequences of poor drug therapy

Answer 1

No therapeutic benefit
Side effects
Poor compliance
Drug interactions
Drug resistance

Question 2

what are the main objectives of drug therapy?

Answer 2

Get the right drug
in the right space
at the right concentration
for the right period of time

Question 3

what is pharmacodynamics?

Answer 3

Mechanism of action (molecular target and physiology), dosing, side effects

Question 4

what is pharmacokinetics?

Answer 4

ADME

-absorption, duration, metabolism and excretion

Question 5

what are the X and Y axises in a dose-response curve?

Answer 5

x=dose

y=response

Question 6

what is EC50?

Answer 6

effective concentration to produce 50% of maximal response (measure of potency)

Question 7

what is the difference between EC50 and ED50?

Answer 7

ED 50 uses the DOSE of drug producing 50% of maximal response to compare potencies rather than concentration

Question 8

what is IC50?

Answer 8

inhibitory concentration

Question 9

What is TD50?

Answer 9

toxic dose

Question 10

What is LD50?

Answer 10

lethal dose

Question 11

what is efficacy?

Answer 11

the level of effect a drug elicits

Question 12

what is potency?

Answer 12

the amount or concentration of a drug responsible for a response
(high potency = big effect from small amount)

Question 13

when comparing potency, what values can you compare?

Answer 13

ED50

Question 14

what does the therapeutic index quantify?

Answer 14

quantifies side-effects

Question 15

name a drug that has no side effects

Answer 15

there isn’t one

Question 16

what causes side effects?

Answer 16

Most side effects are mechanism based

• Due to therapeutic mechanism of action
• Due to off-target mechanism of action
• Due to interaction/interference with other drugs (competition)
• Often, but not always, dose-dependent

Question 17

what are some common side effects of anesthesia?

Answer 17

Nausea and vomiting
Cognitive dysfunction
Muscle ache/fatigue
Itching sensations
Emotional reactions

Question 18

which drug often creates the effect? bound or free?

Answer 18

the free drug

Question 19

for a therapeutic index, the _____ the ratio, the safer the drug

Answer 19

larger

Question 20

what are some main mechanisms of drug action?

Answer 20

Act directly or indirectly on receptors, channels, transporters or enzymes;
Act competitively or irreversibly
Mimic or antagonize endogenous substances
Drugs and drug target can be pleiotropic (effect many parts) or very specific
Can impair key point(s) in a metabolic chain to collapse the whole