If Drug a Has an ED₅₀ Value of 12

question 46

Multiple Choice

If drug A has an ED₅₀ value of 12.0 mg/kg, and drug B has an ED₅₀ value of 4.0 mg/kg, what can we say about the potencies of these drugs?

• A) Drug A is three times more potent than drug B.
• B) Drug A is eight times more potent than drug B.
• C) Drug B is three times more potent than drug A.
• D) Drug B is eight times more potent than drug A.

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Definitions:

Difference Threshold

The minimum difference in stimulation that a person can detect 50% of the time, also known as the just noticeable difference.

Retina

The light-sensitive inner surface of the eye, containing the receptor rods and cones plus layers of neurons that begin the processing of visual information.

Retinal Disparity

A binocular cue for perceiving depth. By comparing retinal images from the two eyes, the brain computes distance— the greater the disparity (difference) between the two images, the closer the object.

Blind Spot

The point at which the optic nerve leaves the eye, creating a “blind” spot because no receptor cells are located there.