Drug Action Exam 1 Practice Test 2026 – Your All-in-One Guide to Exam Success!

Intrinsic activity is about what happens after the drug binds to its receptor—the ability of the bound drug to generate a biological response. It reflects the drug’s efficacy: a full agonist has high intrinsic activity and can produce a strong, near-maximal response; a partial agonist has lower intrinsic activity and elicits a smaller response even when bound; antagonists bind but do not activate the receptor, so their intrinsic activity is zero. This concept is distinct from affinity, which is how tightly a drug binds, and from pharmacokinetics like how quickly a drug is eliminated or how it distributes in tissues.