Cellular Receptors and Drug Action

What are Agonists?

Drugs, upon binding to its receptor, activate it, which will effect the cell

What are Antagonists?

Drugs that bind to a receptor, and blocks its original agonist or other cells

What are the 3 types of agonists?

Full, Partial and Inverse

Define a Full Agonist, and give an example

• Drugs that, upon binding to a receptor, exert the same full effect as the natural chemical it WAS supposed to bind to

  • e.g. Dexamethasone is an agonist; it exerts the same effect on cortisol receptors, which was meant for endogenous cortisol

Define Partial Agonists

Drugs that bind to a receptor meant for an endogenous molecule, but exerts a weaker effect than full agonists and their origical molecule

Define Inverse Agonists (2), give one example

1. Binds to receptors but exerts the opposite effect

2. Turns down baselne activity or shutting down the receptor’s natural activity

e.x. GABA receptors receive benzodiapines as agonists which creates sedation + calmness, but inverse agonists can instead cause pain and restlessness

What are the 2 types of antagonists?

Reversible, Irreversible Antagonists

Define Reversible Antagonists.

Antagonistic drugs that can remove itself from the receptor if needed

What are 2 types of Reversible Antagonists? Define both?

1. Competitive Antagonists: competes/blocks agonist or origonal molecule particles from binding to receptor

2. Noncompetitve Antagonists: performs allosteric modulation; binds to surface of cell instead of directly on te receptor, but causes the receptor to change shape remotely, which prevents fitting between agonist/molecule and receptor

What are Irreversible Antagonists? Give an example

• Drugs that bind to receptor and basically stays there to fully exterminate the cell

e.x. Aspirin binds and fully kills the cell

Acronym, What are G-coupled protein receptors?

GPCR: Types of receptors that, upon binded to, activates a g protein located endegenous but near the cell membrane, and performs its intended purpose of creating a therapeutic effect, or just causing something

What are 4 types of G proteins

Gs (Stimulatory), Gi (Inhibitory), Gq (Phospholipase C), G-Ion Channeled

What is Gs, what is its effector, What is its secondary messenger, and what isa its MAIN PURPOSE/EFFECT; give an exampleis

1. G protein, used for stimulation

2. Effector: Adenyl Cyclase

3. Secondary Messeger: increases cAMP, made from converting ATP into it

4. Elevating cellular activities

5. Albuterol: relaxes airways, promotes bronchodilation

What is Gi, what is its effector, What is its secondary messenger, and what is its MAIN PURPOSE/EFFECT; give an example

1. G protein, used for inhibitory effects

2. Effector: Adenyl Cyclase

3. Secondary Messenger: Decreases cAMP

4. Main Effect: Lower Cellular Activity

5. Misoprostol lowers acid in the stomach

What is Gq, what is its effector, What is its secondary messenger, and what isa its MAIN PURPOSE/EFFECT; give an example

1. Used to increase intracellular calcium, IP3 and DAG

2. Phospholipase C

3. IP3 and DAG is elevated

4. IP3: increase intracellular calcium for contractions, DAG promotes phosphorylation of proteins via Protein Kinase C

5. Ergonovine (promotes uterine contractions for babies)

What is G (ion channels), what is its effector, What is its secondary messenger, and what is its MAIN PURPOSE/EFFECT; give an example

1. Used to regulate potassium exit from the cell

2. Potassium channel

3. N/A

4. Hyperpolarization (relaxes )

5. Bethanechol