Drug Receptor Interaction Flashcards
why is it important to study drug receptors?
- drug development based in understanding receptors
- for chemical toxicity: toxic mechanisms are receptor mediated
- for viral toxicity: viruses and microorganisms can target receptors
what are inotropic receptors and what are some examples?
- also known as ligand gated ion channels
- occurs in milliseconds (ms)
-Ach, nicotinic
what are metabotropic receptors and what are some examples?
- also known as G protein coupled receptors
- occurs in seconds
-Ach, muscarinic
how do ionotropic receptors work?
- channel only opens when a specific chemical binds to the receptors
- allows ions to enter/leave the cell
- leads to hyper/depopolarisation of the cell
how do metabotropic receptors work?
- when chemical binds to receptor, causes cascade of 2° messengers
- will activate the G protein that inhibits/activates and enzyme
- can lead to phosphorylation, release of Ca2+ or induce opening of other ion channels
- leads to pharmacological response
what is an agonist?
a drug that binds to receptor and illicit a biological response
what is an antagonist?
- a drug that blocks the action of the agonist compound
- binds to the receptor w/o eliciting a biological response
what is a partial agonist?
an agonist that produces a biological effect without reaching the maximal effect
what is an inverse agonist?
an agonist that produces the opposing biological response observed by full agonist
what is affinity?
- the ability of a drug molecule to bind to the receptor site
- Ka shows the affinity of the drug
what is efficacy?
the ability of a drug to elicit a biological respond from a drug receptor
-measured by eC
what determines how ‘tight’ the agonist binds to the receptor?
- the bond type
- weak bonds (reversible binding dissociation): H bonds, ionic bonds, van Der Waal’s
- strong bonds (irreversible binding): covalent bonds
why is receptor binding important?
- helps localise functions
- helps see function of the receptors and the biological response associated
what does the law of mass action govern?
- the reversible binding of an agonist
- dependent on [reactant] involved
what is the law of mass actopm?
- as you increase [A] or [Rfree], [AR] increases
- eventually [AR] fully saturated as all Rfree used up
what is Kd?
- Kd is the eqm dissociation constant (reciprocal of Ka) and is also a measure of affinity
- it is where 50% of the max number of receptors are bound
- lower Kd = higher affinity
what is the Bmax?
the maximum number of receptors bound to a drug
what is potency?
the [drug] needed for effect
-less drug required = more potent the drug
explain how buprenorphine is used to treat heroin addicts
- substitution therapy
- buprenorphine has higher affinity to heroin receptors so they displace heroine
- buprenorphine is a partial agonist: still elicits ‘happy’ feeling but not as intense as heroin
- used to reduce withdrawal symptoms
- used to reduce desire for heroin
what are competitive antagonists?
drugs that compete w agonists for the binding sites
what are non competitive agonists?
drugs that bind to a different site to the agonist to cause functional blockade // or binds to allosteric site of receptor to cause a conformation
what is done to overcome the effects of a competitive antagonist and give an example of when this is used?
-increase [A] to overcome effects of Ant
- Used in drug overdose:
- drug overdose causes respiratory depression
- reverse respiratory depression by blocking opioid receptors increasing naloxone (which acts as an opioid antagonist)
