Drug Receptor Interaction Flashcards
State and explain 4 reasons behind the importance of understanding receptors
Pharmaceutical industry and drug development - 34/100 drugs on the market target GPCR
Physiology of endogenous transmitters - Act primarily upon receptor targets
Chemical toxicity - Many toxic mechanisms are receptor mediated
Viral toxicity - Viruses and other microorganisms can target receptors
What is a partial agonist
Agonist that does not produce as strong a response as the full agonist. Has antagonistic properties
Inverse agonist
An agonist that produces an opposing biological response to that observed by a full agonist
Define efficacy
Ability of a drug to elicit a biological response from a drug receptor interaction
The more effect the drug has, the more efficacious
What types of bonds form between agonist and receptors?
Hydrogen bonding - Reversible binding dissociation
Ionic
VdW forces
Covalent binding - Irreversible, poor dissociation
Why is receptor binding important
Morphine - Opioid receptors, brain painkiller
What determines drug affinity
Law of mass action - Dependent on concentration of the reactants involved
Agonist + Receptor -> <- Agonist-Receptor complex AR
Association rate k1
Dissociation rate k-1
What happens as you increase drug conc
More receptors bind to drug drug-receptor interaction. Graph begins to level out as more and more receptors are occupied, graph plateaus. Saturation
What is Kd?
Measure of affinity - Concentration of drug where 50% of max number of receptors are bound by the drug
The ability of a drug molecule to bind to a receptor site
What is Bmax
max number of receptors bound by the drug
What is potency
The concentration of the drug needed for the effect. The less concentration required, the more potent the drug
State and describe partial agonists
E.g. buprenorphine for opioid addiction
Present at receptors - High affinity, but less efficacy
Reduces withdrawal effects
Reduces additive ‘highs’
Heroin-induced highs are reduced in presence of partial agonist
Describe competitive antagonism
Agonist and antagonist compete for same binding site. [A] must increase to overcome antagonist binding to receptors.
Non-competitive antagonism
Antagonist binds to a different site from the agonist
e.g.
Ketamine blocks glutamine receptors by acting at a different site in the receptor structure to glutamate
