Murphy Receptors Flashcards
Drug Receptor Anatomy
Described as lock and key fitting for receptor activation
Location of target proteins for current drugs
Cell Membrane - 62% Unknown - 15% Exterior - 8% Cytoplasm - 6% Nucleus - 6% Organelles - 4%
4 Superfamilies of Physiologic Receptors
Ion Channel Receptors
G-Coupled Protein Receptors (GPCR)
Enzyme Receptors
Nuclear Receptors
All are effected by agonists
Adrenergic Receptors
Denoting nerve cells in which epinephrine and norepinephrine act as neurotransmitters.
Subclass of Adrenergic Receptors
Drugs can be selective or non selective for all of these:
- ————————————————–a-1A
- ———————————Alpha 1 ——a-1B
- ————————————————–a-1D
- Alpha Receptors ——-
- ————————————————–a-2A
- ———————————Alpha 2 —–a-2B
- ————————————————–a-2C
- ————————————————–B-1
- Beta Receptors—————————-B-2
- ————————————————–B-3
Specific Drugs
Drugs that only have 1 target (rare)
Selective Drugs
When at a given concentration a drug only has 1 target
Non-Selective Drugs
Drugs that have more than one target at a given concentration
Types of chemical bonding forces
Ionic
Hydrogen
Van Der Walls
(Covalent)
Kd
Dissociation constant which is determined by the affinity of a receptors to drugs based on ligand concentration. Kd can be described as the concentration of ligand at equilibrium that causes a percentage of receptors to be ligand bound. Kd = concentration of drug occupying 50% of receptors.
Fractional Occupancy
The fraction of receptors occupied at a particular ligand concentration. Fractional Concentration = LR / R (tot)
Effect of Kd on Potency
A low Kd will equate to a high drug affinity to receptors and therefore a high potency
A high Kd will equate to a low drug affinity to receptors and therefore a low potency
Explain why EC50 does not equal Kd most of the time
Non-Linear systems
Receptor activation equilibrium
Competition with endogenous activators
Impaired drug access to receptors
