Drug Receptor Action Flashcards
What are the 4 different levels that drugs act pharmacodynamically?
Molecular, cellular, tissue and systemic
What does the site of action refer to ?
Where the drug experts any benefits
The drug action
- can be determined by drug specifity
What is an antagonist?
No effect, mediators are blocked
What is a direct agonist receptor ?
Ion channel opening/closing
What is an angonist transduction mechanism?
- enzyme activation/inhibition
-ion channel modulation
-DNA transcription
What’s the difference between and ion channel blocker and modulator?
Blocker- permeation blocked
Modulator- increased/decreased opening probability
What does an enzyme inhibitor do ?
Normal reaction in inhibited
What does a false substrate do?
Abnormal metabolite produced
What does a pro-drug do?
Active drug produced
What types of transport are there? (Not chemical)
Inhibitor- blocks transport
False substrate- abnormal compound accumulated
What are the two types of receptor ?
Ligand gated ion channels (ionotropic)
G-protein-coupled receptors (metabotropic- initiates metabolic reactions)
What is Em ?
Resting membrane potential
What do ion channels do ?
They are protein pores in cell membranes
Allow selective transfer of K+, Na+, Ca2+, Cl-
Can be opened/closed to allow control of ion transfer and Em
Made of subunits
How are ion channels regulated?
When a molecule binds to a receptor site
OR
Changes in Em
What’s an example of a ligand gated ion channel ?
Nicotinic Acetylcholine receptor
Give an example of a Nuero-muscular blocking drug
D-tubocurarine,
Anatagonist at nicotinic Ach receptors in skeletal muscles
Competitive anatogonist with Ach
Used in surgery as a paralytic
What are the potential drug targets for ion channels ?
-Altered gating
-channel block
-block of inactivation
How is a GPCR different to an ion channel ?
- coupled to signalling pathway
- only one subunit
- uses a relay system
What is a ‘relay’?
- type of protein
- G-protein (guanosine nucleotide binding protein)
- G protein links receptor to Intracellular signalling pathways
Describe the structure of a G-protein.
-Usually composed of one subunit
-inserted in cell membrane and have extra/intracellular regions
-have an agonist binding site on extracellular region
What do each of the subunits of a G-protein look like ?
Give an example of a G-protein receptor.
Beta-adrenergic receptor (adrenoceptor)
Where are adrenoceptors found?
Throughout Cardiovascular, respiratory and nervous systems
What happens when adrenoceptors are activated in heart?
- lead to increase in force and rate of contraction
- activation of receptor in turn activated signalling pathway inside heart muscle cells via g-protein
