You plotted concentration–response (CR) curves by adjusting the KE (equilibrium dissociation constant) of the agonist.

You learned that:

• Higher KE = lower affinity → curve shifts right

• Under simple conditions, KE ≈ EC₅₀ = the agonist concentration that produces 50% of maximal response.

(STEP 1) To compare the potency of propranolol and metoprolol at β₁-adrenoceptors, you should look at how much each drug shifts the concentration–response curve of an agonist (like adrenaline) to the right.

Both propranolol and metoprolol were used at the same concentration, but proponolol greater shift

Conclusion: Propanolol = A greater rightward shift = greater ability to block the agonist = higher potency.

(STEP 2)You looked at how adrenaline’s effect on heart rate is altered by:

• Propranolol (non-selective β-blocker)

• Metoprolol (β1-selective blocker)

You saw that propranolol blocks both β1 and β2, while metoprolol blocks mainly β1 = highlighting their difference in selectivity.