Pharmacodynamics Flashcards
(26 cards)
Define affinity
How well a drug binds to a receptor
Define efficacy
How effective a drug is at producing an action once bound
Define potency
How much of a drug is needed to elicit a response
Define selectivity
How selective a drug is at choosing a receptor
What is the ‘duration of binding’
How loing a drug stays bound to a receptor
What is desensitisation
This refers to when a drug is still bound to a receptor, but a response is no longer elicited.
What is drug tolerance?
A receptor needs more of the drug to have the same effect as before
Downregulation
There are fewer receptors avaliable for a drug to bind to
What is an Agonist
A drug that activates and increases the activity of a receptor
What is an antagonist
A drug that blocks a receptor
What is a partial agonist
A drug that partially activates a receptor
What is an inverse agonist
Reduced the activity of a receptor
Explain what upregulate means
The sensitivity of receptors to a signal is increased
Explain what downregulate means
The sesntivity of a receptor to a signal is decreased
How can a cell upregulate or downregulate?
By changing the numbger of receptros to a given hormone or neurotransmitter
What is EC50
A measure of the potency of a drug. EC50 = the dose at which 50% of maximal effects are elicited
Four receptor types
Ion channel
G-Protein
Kinase
Nuclear
How is a ligand gated channel opened?
When an agonist binds to the channel it open within milliseconds
How do G-protein coupled receptors (GPCR) work?
A ligand binds at the extracellularsite and activates signal transduction pathways inside the cell. This results in a cellular response
Why would a low selectivity result in more side effects?
The ligand is less selective to the target receptor, it may therefore bind to non-intended receptors which produces unwanted effects
What happends at a kinase receptor when a ligand binds?
Autophosphorylation of the receptor leading to a cellular response
What happends when a ligand binds to a nuclear receptor?
A change in DNA expression leading to a change in gene expression
Ion channels are either …. gated or …. gated
Voltage gated or ligand gates
Uniporter proteins do what
Facilitate the movement of one small molecule in one direction
