drug receptor interaction Flashcards
what is the importance of studying receptors
pharmaceutical industry and drug development
physiology of endogenous transmitters: transmitters and hormones act primarily upon receptor targets
chemical toxicity;many toxic mechanisms are receptor mediated
viral toxicity; viruses and other microorganisms can target receptors
what are the types of receptors
ligand-gated ion channels(ionotropic receptors)
G-protein coupled receptors(metabotropic receptors)
tyrosine-kinase receptors
nuclear receptors
what is an agonist
this is a drug that binds to a receptor, activates them and elicits a biological response
what is a partial agoinist
a partial agonist is a drug that produces a biological response but never the maximal tissue capacity. it possesses antagonistic properties.
what is an antagonist
this is a drug that blocks the action of an agonist commonly by binding to a receptor but never eliciting a biological response.
what is an inverse agonist
this is a drug that produces an opposing effect of the biological response an agonist would produce.
what is the affinity of a drug
this is the ability of an agonist to bind to a receptor. it is a measure of how tightly or loosely a drug binds to a receptor.
what is the efficacy of a drug
this is the ability of a drug to elicit a biological response from a drug-receptor interaction. a full agonist has a higher efficacy than a partial agonist.
what happens when an agonist is added to a population of receptors
the agonist binds to the receptors to form an agonist-receptor complex. what governs this binding is called affinity.
what bonds can be formed between a receptor and a drug and a receptor
hydrogen bonding
ionic bonding
van der Waals forces
These three forces are relatively weak, are reversible binding, and have good dissociation
covalent bonding- has stable strong bonds, irreversible binding, poor dissociation and is very rare.
how do most agonists bind to their receptors
reversibly
what is the reversible binding of agonists governed by?
law of mass action
what is the law of mass action
this law states that the reversibility of binding is dependent on the concentration of reactants involved.
what does the law of mass action predict?
Low [A] - lots of Rfree - few AR interactions
Increase [A] - more AR interactions - reaction driven to right
Continue increasing [A] – few Rfree, the reaction reaches maximal
what is Kd of a drug
each drug has its own Kd. the Kd of a drug is the conc of a drug where 50% of the max number of receptors are bound by the drug.
Kd is inversely proportional to affinity, the higher the affinity, the lower the Kd.
what is Bmax
this is the max number of receptors bound by a drug.
what is the threshold conc of a drug
this is the minimum conc of drug required to produce a pharmacological rrsponse
what is EC50?
this is the conc of the drug required to produce 50% pharmacological response.it is used to deterine the potency of a drug; the higher the EC50, the less potent a drug is.
What is the maximum pharmacological effect
Efficacy
what is the potency of a drug
this refers to the concentration of a drug needed for a pharmacological effect to occur. the more conc needed, the less potent a drug is.
why is only a small number of drug-receptor interactions able to produce biological effects?
because receptors amplify signals.
explain buprenorphine action
buprenorphine is an opioid partial agonist which has a high affinity for the opioid receptor. it is used to help those with opioid addiction. it binds to the receptor thereby stopping opioids from binding to their receptors.
what is a competitive antagonist
this is an antagonist that binds to the same site as an agonist. the agonist and competitive antagonist both bind reversibly. the agonist must increase in concentration to overcome the antagonist binding to the receptor. it is a surmountable antagonism
what is a non-competitive antagonist
the antagonist binds to a different site from the agonist and cause a functional impairment of the receptor and as a result, the agonist is unable to bind to its receptor. here, the EC50 remains the same but efficacy is reduced.
