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What does an agonist have in terms of affinity and efficacy?
high affinity and high efficacy
A drug causes immediate muscle paralysis during surgery by blocking nicotinic acetylcholine receptors. What receptor type is involved?
Ligand-gated ion channel (LGIC)
Some receptors are active even when no ligand is bound. What is this activity called?
Constitutive activity
What does an antagonist have in terms of affinity and efficacy?
high affinity and low / zero efficacy
Newer ‘biologic’ drugs such as monoclonal antibodies can work by different inhibitory actions to traditional receptor antagonists. Name one of these different actions.
bind to the agonist and prevent it binding to the receptor / cause receptor internalisation
Salbutamol activates β₂-adrenoceptors to open airways.
What type of receptor are these?
GPCR
Which receptor type is more commonly involved in neurotransmission at synapses?
LGIC
A drug binds to a site different from the agonist binding site and changes receptor activity. What type of drug is this?
Allosteric modulator
A drug reduces the maximal effect of an agonist even at high agonist doses.
What type of antagonist is this?
Non-competitive antagonist
Other than LGICs and GPCRs, name the other 2 receptor subtypes?
TK receptors and nuclear receptors
Can a partial agonist reduce the effect of a full agonist?
Yes
What happens to basal activity when an inverse agonist is given?
It decreases
A receptor shows constitutive activity. You give a drug and the basal signalling decreases. What type of drug is this?
Inverse agonist
A drug shifts the agonist dose–response curve to the right without lowering Emax.
What type of antagonist is this?
Competitive antagonist
Apart for receptors, what are the other 3 main protein targets for drugs?
ion channels, enzymes and transporters (carriers)
A drug shifts the agonist dose–response curve to the right and lowers Emax.
What type of antagonist is this?
Non-competitive antagonist
Why are LGIC responses faster than GPCR responses?
They directly open ion channels
Which receptor type uses second messengers like cAMP or IP₃?
GPCR
What does a partial agonist have in terms of efficacy compared with a full agonist?
Lower efficacy
What type of receptor class does insulin act at?
Tyrosine kinase receptors
Where are G-protein–coupled receptors (GPCRs) located?
On the cell membrane
Why do steroid drugs take hours to work?
They alter gene transcription
Does increasing dose change a drug’s efficacy - Yes or No?
No
True or false: Partial agonists have zero efficay
False.
What are the names given to the ACh LGIC and GPCRs?
nicotinic, muscarinic