Theme 4 - Pharamcodynamics Flashcards
Define pharmacodynamics
Study of drug effect and mechanism of action (what drug does to body)
Define “drug”
A chemical substance of known structure, other than a nutrient or an essential dietary ingredient, which, when administered to a living organism, produces a biological effect.
Define “medicine”
The dosage forms in which drugs are administered (capsules, tablets, mixtures), contain more than one drug as well as inactive substances necessary during its manufacturing process.
What are the 5 Targets of drug action?
Simple chemical neutralisation Enzyme inhibitors Receptor occupying drugs Modulators of certain transport systems Ion channel interaction
Define the term “receptor”
A protein macromolecule with positions in its 3D structure that is of such a nature that they have chemo recognising properties for a specific endogenous molecule or a specific drug (it is also stereospecific)
What are the 4 receptor types?
- Ligand-gated ion channels (ionotropic receptors)
- G-protein-coupled receptors (metabotropic receptors)
- Kinase-linkedreceptors
- Nuclear receptors
Give examples of drug-receptor binding interaction
Enzyme-substrate binding
Binding of fatty acids and drugs to plasma proteins (albumin)
Binding of antigens to antibodies
What are the 4 main types of drug-receptor bonds?
Covalent, electrostatic, hydrophobic, cation-π
Which receptors are Class I receptors related to?
nicotinic acetylcholine receptor
What do class I receptors have in common with regards to the number of subunits?
All have the same number of subunits
How do Class I receptors function?
By the fast opening of an ion channel
What are Class II receptors coupled to?
second messenger system
At what rate do Class II receptors operate?
rate much slower than class I receptors
What does the protein composition of all class II receptors have?
7 membrane crossing segments
What is the relationship between amino acid sequences of class II receptors?
they are all similar
What is Receptor equilibrium?
A receptor exists in a dynamic equilibrium in two states Ri (active state) and R* (inactive state)
What is intrinsic activity?
The ability to elicit a response after binding to a receptor
What is a full agonist?
When the concentration of the agonist is increased, the biological response will increase until the maximal response has been reached
What is a partial agonist?
Will not be able to produce 100% of the biological response of the agonist even at very high concentrations
What is an Antagonist?
Antagonists block or reverse the effect of agonists, have no intrinsic activity
What is a Competitive antagonist?
A competitive antagonist competes with the agonist for binding to the receptor. It has affinity for the receptor, but no intrinsic activity
What is a Non-competitive antagonist?
Antagonists that binds to a different part of the receptor than agonists, there is no competition for the same binding site.
What is an Irreversible competitive antagonist?
The antagonist competes directly with the agonist for receptor binding. However, the binding forces between the antagonist and receptor are so strong that the antagonist- receptor complex is irreversible.
What is a Physiological antagonist?
Drugs cause opposite effects on the same system having different receptors.
What is a chemical antagonist?
These antagonists bind to the active drug and inactivate
What is the receptor reserve?
The maximum response can be obtained without the agonist occupying all the receptors. This excess of receptors is in reserve.
What is the down-regulation of receptor numbers?
chronic stimulation by agonists cause a decrease in receptor numbers
What is the up-regulation of receptor numbers?
chronic inhibition by antagonists cause an increase in receptor numbers
What is a second messenger system?
A second system that communicates with the interior of the cell.
