Which two properties must a drug possess to activate receptors?

Which two properties must a drug possess to activate receptors?

• A. Only high affinity
• B. Neither
• C. Both great affinity and intrinsic activity
• D. Only intrinsic activity

Answer: (C)

Activating a receptor requires two things: the drug must bind to the receptor (affinity) and, once bound, it must trigger a response (intrinsic activity or efficacy). If a molecule binds well but doesn’t activate the receptor, it acts like an antagonist and doesn’t produce signaling. If a molecule activates the receptor but doesn’t bind effectively, it won’t produce any effect because it can’t occupy receptors in the first place. Only a compound that both binds well and can activate the receptor will reliably produce a physiological response. That’s why having both strong affinity and intrinsic activity best explains receptor activation.

Activating a receptor requires two things: the drug must bind to the receptor (affinity) and, once bound, it must trigger a response (intrinsic activity or efficacy). If a molecule binds well but doesn’t activate the receptor, it acts like an antagonist and doesn’t produce signaling. If a molecule activates the receptor but doesn’t bind effectively, it won’t produce any effect because it can’t occupy receptors in the first place. Only a compound that both binds well and can activate the receptor will reliably produce a physiological response. That’s why having both strong affinity and intrinsic activity best explains receptor activation.