1.1 Receptors Flashcards
(21 cards)
- What is the fundamental principle of how drugs work?
Drugs must bind to drug targets to exert effects.
- Who first proposed that drugs must bind to targets to act?
Paul Ehrlich – “Entities (drugs) do not act unless attached.”
- What are common drug targets?
Receptors, enzymes, ion channels, transporters, DNA.
- What percentage of drugs act on receptors?
~45%
- What is the role of receptors in the cell?
They are sensing elements that recognize endogenous molecules and transduce signals to alter cell activity.
- What are ligands?
Molecules (e.g., drugs, hormones) that bind to receptors.
- What forces allow ligand binding to receptors?
Hydrogen bonds, ionic bonds, van der Waals forces.
- What is a binding site?
A cavity in the receptor formed by amino acids that complement the ligand’s shape and chemistry.
- What determines the strength of drug binding?
Type of chemical bond, number of bonds, and distance between ligand and receptor.
- What is affinity?
The tendency of a drug to bind to its target.
- What factors influence affinity?
Complementary 3D shapes and chemical forces between the drug and receptor.
- What is the equilibrium dissociation constant (KA)?
The concentration of drug at which 50% of receptors are bound.
- What does a low KA indicate?
High affinity.
- What is the relationship between affinity and drug concentration?
Higher [drug] drives more binding, according to the Law of Mass Action.
- What is the Hill equation for fractional receptor occupancy?
y=[D][D]+KAy = \frac{[D]}{[D] + K_A}y=[D]+KA[D]
- What is selectivity in pharmacology?
The ability of a drug to bind preferentially to one target over others.
- How is selectivity related to affinity?
High affinity for one target allows selective binding at low [drug], minimizing off-target effects.
- Why is selectivity lost at high drug concentrations?
At high [drug], the drug can bind to lower-affinity targets, potentially causing side effects.
- Is selectivity absolute?
No – it’s a relative and concentration-dependent property.
- Give an example of a selective drug and its target.
Salbutamol – selective β2-adrenoceptor agonist.
What are the key points for ligand binding revision?
- Drugs must bind to targets to work
- Binding involves weak chemical forces
- Fractional binding depends on [drug] and KA
- KA is a measure of affinity
- High affinity enables selectivity, which may be lost at high doses
