Measuring Drug Action

1
Measuring Drug Action

• Dose Response Curves

Response ? fraction bound (fb)
2
Measuring Drug Action

• Dose Response Curves

90
IC50 or EC50 or LD50
50
IC90 or EC90 or LD90
Inhibition Concentration Effective
Concentration Lethal Dose
Or Log agonistO
Agonist An agent that facilitates or enhances
the normal action of a receptor. Antagonist An
agent that prevents the normal action of a
receptor.
3
Measuring Drug Action

• Dose Response Curves

4
Measuring Drug Action

• Efficacy and Potency

Potency corresponds to the strength of a
drug, while Efficacy corresponds to the
effectiveness of a drug. e.g., if 1 mg of
drug A relieves pain as effectively as 10 mg of
drug B, drug A is twice as potent as drug B
the diuretic furosemide eliminates much more salt
and water through urine than does the diuretic
chlorothiazide. Thus, furosemide has greater
efficacy than chlorothiazide.
5
Measuring Drug Action

• Efficacy / Potency / Toxicity

100
100
Desired Response ()
Toxicity ()
50
50
0
0
Log Drug
Blue lines . Drug 1 Red lines . Drug 2 Solid
lines . Desired response Dotted lines .
Toxicity response
6
Measuring Drug Action

• How are these drug-response profiles generated?

e.g., anticoagulants and inhibition of
pro-coagulant enzymes
7
Measuring Drug Action

• How are these drug-response profiles generated?

• Cellular/Pharmacological assays

8
Measuring Drug Action

• How are these drug-response profiles generated?

• High Throughput Screening Assays

• Simultaneous . 96- or 384-well microtiter plates
  . robotic analysis
• Chromogenic substrates . develop color
• Yes or No answer .. fixed concentration of drug
• Quantitative . may also give you KI values!!