Pharmacodynamics Flashcards
What are the 4 receptor families?
Ligand-gated ion channels
G-protein coupled receptors
Kinase linked receptors
Nuclear receptors
How do ligand-gated ion channels work
Ligand bind
Facilitate movement of ion across membrane- depolarisation or hyper polarisation which bring effect
How do G-protein coupled receptors work?
GalpaS and I work with same enzyme but AlphaI inhibit adenylyl cyclase
Adenylyl cyclase convert aMp to cAMP, influence PKA bring cellular event
G
GalphaQ activates phospholipase C, convert PIP2 to DAG (influence PKC) and IP3 (calcium regulator)
Or affect ion channel
How do nuclear receptors work?
Receptor inside cell in cytosol, binding to it causes it to bind to DNA, to increase or decrease gene expression
Which receptors are fastest?
Ligand gated- millisecond
G protein- seconds
Kinase-linked receptor - hours
Nuclear receptors- hours
How do kinase-linked receptors work?
Lead to protein phosphorylation
Gene transcription
Protein synthesis
Cellular effects
Agonist drugs
Activate receptors
Antagonist drugs
Block receptors
Affinity
How well a drug binds to receptor
Efficacy
How well it causes a recordable response
2 phases an agonist works
Drug binding- affinity
Receptor activation- efficacy
Biological effect
What is a full agonist?
elicit 100% effect on endogenous agonist
High efficacy
Partial agonist
Elicit<100% effect of endogenous agonist
Low efficacy, not full response
Super agonist
100% endogenous effect- bring greater effect
Inverse agonist
Reduce basal receptor activity
Lower basal rate
Potency meaning
Product of affinity and efficacy
Conc or amount of drug to produce desired effect
Antagonists have how much efficacy
0
Different non-receptor antagonists and explanation
Chemical antagonist- binding an inactivating unbound drug in solution, allow to be excreted
Physiological antagonist- produce opposite physiological effects of another agonist, indirectly oppose action of that original agonist
Pharmacokinetic- drug influence action of another
A full agonist doesn’t need to bind to all receptors in tissues to bring about max response
True or false?
True
A partial agonist will be at 100% receptor occupancy and still not get 100% effect
True or false?
True
Dissociation constant
Conc of drug required to occupy 50% of available receptors
Desensitization
A drug effectiveness may decrease rapidly when given repeatedly or continuously
Tolerance
Decrease in drugs effectiveness over days/weeks
Resistance
Adaptive changes making body less response and so less effective
