Lect 1 Flashcards
(16 cards)
How do drugs act?
By binding to drug targets such as receptors, transporters, ion channels, and enzymes.
What do receptors do?
Recognize the drug and transduce signals to change cell activity.
What is the structure of receptors?
Receptors are proteins with more than 300 amino acids and have binding sites.
What determines binding at receptor sites?
The complementary 3D shapes and chemical forces of attraction such as Van der Waals forces, hydrogen bonds, and ionic interactions.
What is affinity in the context of drug binding?
The tendency of a drug to bind to a target.
What factors influence affinity?
- Complementary chemical forces of attraction
- Complementary 3D shapes between the drug and target
What happens if there is no affinity?
The drug does not bind.
What does the Law of Mass Action state?
As drug concentration increases, the equilibrium shifts right, leading to a greater fraction of targets being bound by the drug.
What is the definition of KA?
The drug concentration at which 50% of the target is bound, serving as a measure of affinity.
What is the relationship between KA and affinity?
An inverse relationship: a low KA indicates high affinity, while a high KA indicates low affinity.
What does high affinity confer in terms of selectivity?
High affinity may confer selectivity for drug targets.
What happens when a drug has high affinity for one target?
It will bind to that target even at low concentrations without binding to other targets with low affinity.
What occurs when drug concentrations increase?
Selectivity can be lost, leading to binding with lower affinity targets.
Is selectivity concentration dependent?
Yes, selectivity is concentration dependent.
Fill in the blank: The measure of affinity is the concentration at which _____ of the available receptors are occupied.
50%
True or False: All drugs are selective in some ways.
True
