Adrenergic Drug Receptors 📶🫀🫁

What are Adrenergic agonists/drugs

Drugs that stimulate the sympathetic nervous system by mimicking norepinephrine and epinephrine (sympathomimetics).

What are adrenergic agonists (aka sympathomimetics) functions

⬆ Heart rate

⬆ Blood pressure

🫁 Open airways (bronchodilation)

🧠 Improve focus (CNS stimulation)

🚽 Slow down digestion and urination

🫀 Shunt blood to vital organs (heart, lungs, brain)

What does a Beta-2 agonist do?

stimulates Beta-2 receptors in the lungs, causing bronchodilation, uterine relaxation, and glycogen breakdown.

🫁 Used for: Asthma, COPD, bronchospasm.

🧪 Examples: Albuterol, Salmeterol

What does a Beta-1 agonist do?

It stimulates Beta-1 receptors in the heart, causing increased heart rate, contractility, and conduction.

❤ Used for: Shock, cardiac arrest, heart failure

🧪 Examples: Dopamine (low dose), Dobutamine

What does an Alpha-1 agonist do?

It stimulates Alpha-1 receptors in blood vessels and eyes, causing vasoconstriction (raises blood pressure) and pupil dilation.

🩸 Used for: Shock, nasal congestion, eye drops

🧪 Examples: Phenylephrine, Oxymetazoline (Afrin)

What does an Alpha-2 agonist do?

It stimulates Alpha-2 receptors in the brain (CNS), which decreases norepinephrine release and lowers blood pressure.

🧠 Used for: Hypertension, withdrawal symptoms

🧪 Example: Clonidine

What does the term “agonist” mean?

An agonist is a drug that activates a receptor, mimicking the effect of natural neurotransmitters.

What does the term “antagonist” mean?

An antagonist is a drug that blocks the receptor, preventing natural signals from having an effect.

How can you tell if a drug is an adrenergic agonist?

• It mimics adrenaline (epinephrine) or norepinephrine

• Causes fight-or-flight effects: ↑ HR, ↑ BP, opens lungs

• Called sympathomimetics or vasoactive

• Usually used for asthma, shock, or allergic reactions

What is the role of the sympathetic nervous system (SNS)?

The SNS prepares the body for “fight or flight” by:

• ↑ Heart rate

• ↑ BP

• Bronchodilation

• ↓ Digestion and urination

• Pupil dilation

Which receptor is mainly found in the heart?

Beta-1

Which receptor is mainly found in the lungs?

Beta-2