Pharmacodynamics Flashcards
7 cards from real Pharmacology practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Pharmacodynamics flashcards as text
A drug that binds to a receptor and produces a submaximal response even at full receptor occupancy is called a:
Answer: Partial agonist
A partial agonist has intrinsic efficacy between 0 and 1, so it cannot produce the maximal response even when all receptors are occupied.
Which pharmacodynamic parameter describes the concentration of drug required to produce 50% of the maximum effect?
Answer: EC50
EC50 (effective concentration 50%) is the drug concentration that produces 50% of the maximal response and is used as a measure of drug potency.
An inverse agonist differs from a competitive antagonist in that it:
Answer: Produces the opposite effect to the agonist by stabilizing the inactive receptor state
An inverse agonist has negative intrinsic efficacy, stabilizing the inactive conformation of the receptor and producing an effect opposite to the agonist.
Tachyphylaxis is best defined as:
Answer: Rapid decrease in response to a drug after repeated administration in a short time
Tachyphylaxis is a rapid, short-term reduction in drug response that occurs after repeated or continuous exposure to a drug.
Which statement correctly describes a quantal dose-response relationship?
Answer: It describes the frequency of a defined all-or-none response in a population
Quantal dose-response curves plot the percentage of a population exhibiting a defined all-or-none endpoint (e.g., death, sleep, seizure) against drug dose.
The therapeutic index is calculated as:
Answer: LD50 / ED50
The therapeutic index = LD50 / ED50; a higher ratio indicates a greater margin of safety between the effective and lethal doses.
Receptor downregulation in response to prolonged agonist exposure typically results in:
Answer: Decreased drug response over time
Prolonged agonist exposure causes receptor internalization and degradation (downregulation), reducing the number of available receptors and diminishing drug effect.