L3: Binding and Agonism Flashcards
What is the difference between a drug and a medicine?
A medicine is made of 1 or more drugs and intended to have a therapeutic effect where benefit»_space; risk
What are the 2 types of drug action?
- Dependent on chemical properties (e.g. antacids that neutralise stomach acid)
- Dependent on biological molecular targets (i.e. drug recognises a specific protein in cells)
What are the 4 different drug targets?
- Receptors
- Ion channels
- Carrier Molecules/Transporters
- Enzymes
What is the difference between an agonist and an antagonist?
- agonist drugs mimic endogenous messengers
- antagonists block endogenous messengers
Define affinity
= how strong the bond is between ligand and receptor
Define efficacy
= ability to generate a response
What do agonists have that antagonists don’t?
efficacy
How do drugs bind to receptors?
Most drugs bind reversibly/transiently
- van der waals, H bonding, ionic interactions
What is the law of mass action?
a chemical reaction is proportional to the concentrations of reactants.
What is Kd?
dissociation constant (mol/L) aka affinity constant
What determines the amount of receptor occupied?
the concentration of the ligand, and its affinity for the receptor
What is affinity?
How strongly a drug binds to a receptor
- Kd = affinity constant = concentration at which 50% of receptors are occupied
What is potency and how is it measured?
Potency (EC50) = the concentration to generate 50% of response
What is efficacy?
the size of the response that the drug produces
What is a partial agonist? How is this different to a normal agonist?
partial agonist - produces less that max response even at 100% receptor occupation
= high affinity, low efficacy
