L2 agonist Flashcards
What is an agonist?
A ligand (drug, hormone or neurotransmitter) that combines with receptors to elicit a cellular response
What is the significance of dose according to Paracelsus?
All things are poisons; it is only the dose which makes a thing poison
What is a graded dose-response curve?
Response of a particular system measured against agonist concentration
What is a quantal dose-response curve?
Drug doses required to produce a specified response determined in each member of a population
What does the EC50 represent?
The concentration or dose required to produce 50% of maximal response
What does the term ‘affinity’ describe?
The strength with which an agonist/drug binds to a receptor
What is the two-state hypothesis in pharmacology?
Describes the resting state (R) and activated state (R*) of receptors
What does a lower Kd indicate about a drug’s affinity?
A tighter ligand-receptor interaction (higher affinity)
What is potency in pharmacology?
The amount of drug needed to produce a given effect (e.g., 50% of Emax)
What characterizes a full agonist?
High efficacy, likely to produce a maximum response with a small percentage of receptors occupied
What characterizes a partial agonist?
Low efficacy, unable to produce a maximum response even when occupying all available receptors
What are inverse agonists?
Compounds that have higher affinity for the inactive state of a receptor than for the active state
What is tachyphylaxis?
The reduction of drug effect with continual/repeated administration
Fill in the blank: The _____ of an agonist is the likelihood that it will bind to and form a stable complex with the receptor.
[affinity]
What is the relationship between receptor occupancy and biological effect?
If linear, Kd and EC50 are equal; however, some systems have spare receptors
What are allosteric modulators?
Compounds that bind to a site other than the active site and modulate receptor activity
What is the difference between positive and negative allosteric modulators?
Positive increase efficacy; negative decrease efficacy of endogenous agonists
What factors contribute to receptor desensitization?
Conformational changes, internalization of receptors, depletion of mediators, altered drug metabolism
True or False: Full agonists can produce a maximal response in the system.
True
True or False: Partial agonists can produce a maximal response in the system.
False
What are the learning outcomes of the session?
Compare potency and efficacy of drugs, determine antagonist type based on dose-response curves
What does the term ‘efficacy’ refer to?
The ability of an agonist to activate a receptor and evoke a cellular action
What is receptor saturation?
The maximum number of binding sites (Bmax) occupied by a drug
What can be inferred from a high affinity drug?
It has a greater tendency to bind to the receptor relative to its dissociation
