Pharmacodynamics and Mechanism of Action 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 and Mechanism of Action flashcards as text
Tachyphylaxis is best described as:
Answer: Rapid tolerance developing within minutes to hours of repeated doses
Tachyphylaxis is rapid, short-term tolerance that develops quickly with repeated administration of a drug (e.g., repeated ephedrine doses).
In a dose-response curve, the slope of the curve in the linear region primarily reflects:
Answer: How rapidly the response increases relative to dose changes
The slope of the dose-response curve reflects the rate at which response increases with dose, indicating the drug's pharmacodynamic sensitivity.
Which statement correctly distinguishes pharmacodynamic tolerance from pharmacokinetic tolerance?
Answer: Pharmacodynamic tolerance involves changes at the receptor level, pharmacokinetic involves changes in drug disposition
Pharmacodynamic tolerance results from receptor-level adaptations (down-regulation, desensitization), while pharmacokinetic tolerance results from altered absorption, distribution, metabolism, or excretion.
Beta-2 adrenergic receptor signaling through Gs leads to bronchodilation via which mechanism?
Answer: Increased cAMP → protein kinase A activation → smooth muscle relaxation
Beta-2 receptor activation increases cAMP via Gs/adenylyl cyclase, activating PKA, which phosphorylates and inhibits myosin light chain kinase, causing smooth muscle relaxation.
A drug that produces opposite effects to the agonist by stabilizing the inactive receptor conformation is called a(n):
Answer: Inverse agonist
An inverse agonist binds the receptor and stabilizes its inactive state, reducing basal (constitutive) activity below baseline.
What is the primary determinant of a drug's intrinsic efficacy?
Answer: The drug's ability to activate the receptor after binding
Intrinsic efficacy reflects a drug's ability to activate a receptor once bound; a full agonist has maximum efficacy, while an antagonist has zero efficacy.
In a two-state receptor model, which drug class shifts the equilibrium entirely toward the inactive receptor conformation?
Answer: Inverse agonist
Inverse agonists have preferential affinity for the inactive receptor conformation, shifting equilibrium away from active states and reducing constitutive activity.