Pharmacodynamic Mechanisms 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 Pharmacodynamic Mechanisms flashcards as text
Which type of receptor mediates the fastest synaptic responses (within milliseconds)?
Answer: Ligand-gated ion channels
Ligand-gated ion channels (ionotropic receptors) open directly upon ligand binding, producing ion flux and membrane potential changes within milliseconds.
Protean agonism describes a situation in which a partial agonist:
Answer: Acts as an agonist in normal tissue but an antagonist in constitutively active systems
In constitutively active receptor systems, a partial agonist can appear to reduce activity (act as inverse agonist) while being a net agonist in non-constitutively active tissue.
Cholinesterase inhibitors like neostigmine exert their pharmacodynamic effect by:
Answer: Preventing breakdown of acetylcholine at the synapse
Neostigmine inhibits acetylcholinesterase, preventing hydrolysis of ACh and thereby increasing its concentration and duration of action at synapses.
The quantal dose-response curve differs from the graded dose-response curve in that it:
Answer: Plots the percentage of a population that responds at each dose
A quantal (all-or-none) dose-response curve plots the cumulative percentage of subjects showing a defined response at each dose level across a population.
Which cellular mechanism underlies the pharmacodynamic action of statins?
Answer: Competitive inhibition of HMG-CoA reductase
Statins competitively inhibit HMG-CoA reductase, the rate-limiting enzyme in cholesterol biosynthesis, reducing intracellular cholesterol and upregulating hepatic LDL receptors.
The term 'pharmacodynamic tolerance' is best illustrated by which scenario?
Answer: Reduced receptor responsiveness despite unchanged plasma drug levels
Pharmacodynamic tolerance occurs when the receptor or effector system adapts, reducing response even though drug concentration at the site remains the same.
Which statement accurately describes the relationship between drug affinity and intrinsic efficacy?
Answer: Affinity and intrinsic efficacy are independent properties
Affinity (how tightly a drug binds) and intrinsic efficacy (the ability to activate the receptor upon binding) are distinct and independent properties of a drug-receptor interaction.