Pharmacology Lecture 3: Drug Receptors

What is the term for what the body does with the drug?

Pharmacokinetics

What is the term for what the drug does to the body?

Pharmacodynamic

What is the main kind of change that occurs when a drug binds with a protein that leads to an alteration of function?

Conformational change

What is the conformational change of proteins mediated by?

Receptors

What are the two drugs that are not mediated by receptors?

1. Simethicone

2. Antacid

After a conformational change, what change occurs due to a stimulus that leads to a pharmacological effect?

Intracellular

What does the potency of a drug rely on?

Affinity by receptors

What does a high affinity by receptors indicate?

Occupies a significant number of receptors in low concentrations

What is the term for the tendency of the drug to bind to the receptor?

Affinity

What is the term for the tendency of the drug, once bound, to activate the receptor?

Efficacy

What is the term for the concentration of agonist that produces half the maximum response?

Potency

If the concentration of agonist that produces half the maximum response is low, is the potency high or low??

High

What is the term for the maximum response to an agonist?

Efficacy

What is the term for a drug that binds to a receptor complex to produce an effect?

Agonist

What is the term for a drug that binds to a receptor but blocks or disrupts actions of an agonist?

Antagonist

Can partial agonists have give a full response?

No

What is the efficacy of all antagonists?

0

What is the term for an antagonist that binds to the same site as the agonist on the receptor and has a reversible bond?

Reversible competitive antagonist

What law is competition of agonists and antagonists governed by?

Law of mass attraction

What is the term for an antagonist that binds to the same site as the agonist on the receptor and never disassociates from the receptor?

Irreversible competitive antagonist

What is the term for an antagonist that binds to another site to the agonist that reduces agonist activity?

Allosteric antagonist

How does an allosteric antagonist affect agonist effects?

Reduce efficacy

Can high agonist concentrations revert the allosteric antagonist effect?

No

How do competitive antagonists affect the potency and efficacy of the agonist?

Potency - Decrease

Efficacy - No change

How do noncompetitive antagonists affect the potency and efficacy of the agonist?

Potency - No change

Efficacy - Decrease

What are the four main types of drug receptors?

1. Ligand-gated ion

2. G-protein coupled

3. Kinase-linked

4. Nuclear

What are the two major categories of drug receptors based on cell responses?

1. Receptors that control ion channels

2. Receptors that regulate secondary messengers

Where are receptors that control ion channels located?

Ligand/Voltage gated channels

Are there secondary messengers involved for receptors that control ion channels?

No

Where are receptors that regulate secondary messengers located?

Cell membrane

What are the cell membrane receptors that regulate the generation of intracellular second messengers?

G-Protein coupled receptors

What is the binding of ligand to G-Protein coupled receptors due to?

Induced fit

What are the two types of cell responses that could occur with ligands binding to G-Protein coupled receptors?

1. Activation/deactivation of cAMP

2. Phosphorylation of proteins

What ligand causes activation/deactivation of cAMP with G-Protein coupled receptors?

Adenylyl cyclase

What ligand causes phosphorylation of proteins with G-Protein coupled receptors?

Phospholipase C

What is the amplification of signal Transduction and response terminated by?

β-Arrestin

What is the term for the decrease in the effect of a drug that occurs quickly in a single dose or in a few administrations?

Tachyphylaxis

What is the term for the decrease in the effect of a drug that occurs gradually?

Tolerance

What are the two changes in receptors that could cause tolerance?

1. Loss of receptors

2. Increase metabolism of substance

What causes desensitization of a drug?

Depletion of mediators

Could you use an LDR curve to estimate the efficacy of agonists?

Yes

Could you use an LDR curve to determine the affinity?

No

Could you use an LDR curve to estimate the potency of agonists?

Yes

Could you use an LDR curve to compare partial and full agonists?

Yes

Could you use an LDR curve to determine the number of receptors?

No

Could you use an LDR curve to determine the presence of spare receptors?

No

Could you use an LDR curve to determine the receptor-effector coupling mechanism?

No

What does the protein Gs do as a secondary messenger?

Activates Ca2+ channels + adenylyl cyclase

What two things does the protein Gi do as a secondary messenger?

1. Inhibit adenylyl cyclase

2. Activates K+ channels

What does the protein G0 do as a secondary messenger?

Inhibits Ca2+ channels

What does the protein Gq do as a secondary messenger?

Activates phospholipase C

If you add a reversible competitive antagonist, could you reach maximum efficacy by adding more agonist?

Yes

If you add a irreversible competitive antagonist, could you reach maximum efficacy by adding more agonist?

No