Drug Receptor Theory Flashcards
What are the molecular targets for drugs
Ion channels
Transporters
Enzymes
What are the types of receptors for drugs?
Ionotropic
Metabotropic
Tyrosine kinase
DNA linked
What are ionotropic drug receptors?
On or inside the cell membrane
Fast response - milliseconds
Ligand gated - binding of ions
Increases or decreases action potentials
What are metabotropic drug receptors?
G-protein coupled receptors
On cell membranes
Medium response - minutes
Ligand gated - hormones and neurotransmitters
(Ligand binds with receptor and then receptor binds with g-protein to transfer ligand)
Example; histamine receptors
What is a tyrosine kinase drug receptor?
On cell membranes
Medium response - seconds to mins
Ligand gated - hormones and growth factors
Example; insulin receptors
What are DNA linked drug receptors?
In the cytoplasm of cell
Slow response - hours
Ligand gated - hormones and glucocorticoids
Activates or inhibits gene transcription
What is an agonist drug?
Drug binds to receptor and produces a response
(Has both affinity and efficacy)
What is an antagonist drug?
Drug binds to receptor and blocks response
(Only has affinity)
What is a partial agonist drug?
Drug agonists which cannot reach 100% response
(Cannot activate enough receptors)
What is drug affinity?
How well a drug binds to receptors
(High affinity = less receptors need binding to, to produce effect)
What is drug efficacy?
How well a drug activates the receptors
(High efficacy = less receptors need activating to produce effect)
What is Kd?
The concentration of the drug needed to occupy 50% of receptors
What is the EC50?
The concentration of the drug that gives you 50% of the response
Why do high efficacy drugs not need to fill every receptor to produce a 100% response?
Because a high efficacy drug has an EC50 much lower than the Kd
This means the agonist does not need to occupy 50% of the receptors to reach 50% response, it can occupy less.
What is the potency of a drug?
How much of the drug needed to produce the maximum effect
What are the types of drug antagonism?
Competitive
Non-competitive
Uncompetitive
Physiological
Define competitive drug antagonism
Binds at the agonist recognition site, preventing access of normal ligand
Can be reversible or irreversible
Define non-competitive drug antagonism
Does not bind at the agonist site, but binds elsewhere to cause conformational change to binding site inhibiting normal agonist binding
Define uncompetitive drug antagonist
Binding occurs to an activated form of the receptor
What are drug antagonists?
Prevent agonists from activating their receptors
Can be reversible or irreversible
Define reversible competitive antagonism
Will eventually dissociate allowing agonist to bind
Temporarily reduces the amount of receptors
Effects can be overcome by increasing amount of agonist
Define irreversible competitive antagonist
Reduces number of available receptors
Eventually will have no receptors for agonist to bind to
