Pharmacology 1: principles Flashcards
What is Pharmacodynamics
What a drug does to the body
What is Pharmacokinetics
The body does to a drug
Describe Affinity
The binding step. The strength of association between ligand and receptor
Describe high vs low affinity
High affinity agonists have a slow dissociation rate and Low affinity agonists have a fast dissociation rate
Describe Efficacy
The activation step. The ability of an agonist to evoke a response.
Do antagonists have affinity or efficacy or both
Antagonists have affinity but no efficacy
How do antagonists bind
To orthosteric (competitive) or allosteric (non-competitive) sites
What is the EC50?
The concentration of agonist which elicits a half-maximal response
What type of plot do we use for the EC50?
Semi-logarithmic.
How is the relationship between concentration and response described?
Sigmoidal
Describe the graph of a Potent agonist, Less Potent agonist, and a partial agonist
In competitive antagonists, in which direction is the response curve shifted?
Parallel to the Right.
Becomes less potent but with higher conc. of agonist the antagonist can be out-competed to produce the same maximal response
In non-competitive antagonists, in thich direction is the response curve shifted?
Slope Flattened.
When the agonist binds, it cannot contribute to maximal response.
With which type of antagonist does EC50 and therefore potency increase
Competitive
What is drug disposition?
The fate of drugs in the body
Absorption, distribution, metabolism, excretion
What are the physiochemical factors controlling absorption
- Solubility
- Chemical stability
- Lipid to water partition coefficient
- Degree of ionisation
What factors affect GI absoption?
GI motility
pH
Blood flow
Physiochemical interactions
Presence of Transporters
Are ionised or unionised drugs more freely able to distribute
Only unionised drugs can freely diffuse. Ionised drugs require transporters to move
What is the Vd?
The apparent volume which a drug is dissolved in
What does Vd <5L imply?
Drug is contained within the vascular component
eg. bound to protein or too large to cross the capillary wall
What does Vd <15L imply
Drug is restricted to extracellular water
What does Vd >15L imply?
distribution throughout total body water
eg. highly lipid soluble drugs
