Question

Choose the correct sequence of decreasing beta receptor agonist potency:

• A. $A>B>C$
• B. $B>C>A$
• C. $A>C>B$
• D. $B>A>C$

Hint:

Isoprenaline is the "Beta-Expert"—it's always the most potent beta-stimulator.

Answer 1

The Correct Option is A

Step 1: Concept
Adrenergic agonists vary in their affinity and potency for different receptor subtypes ($\alpha$, $\beta_1$, $\beta_2$).

Step 2: Meaning
"Potency" here refers to the relative strength of these catecholamines in stimulating beta-adrenoceptors.

Step 3: Analysis
Isoprenaline (A) is a pure and very potent beta-agonist. Adrenaline (B) has strong effects on both alpha and beta receptors. Norepinephrine (C) is primarily an alpha-agonist and has relatively weak activity at beta-2 receptors.

Step 4: Conclusion
The correct decreasing order of beta receptor agonist potency is: Isoprenaline $>$ Adrenaline $>$ Norepinephrine.

Final Answer: (A)