Lecture on Epinephrine and Atropine: Mechanism of Action

Drug Nomenclature

• Chemical Name: Rarely used outside labs
• Generic Name: Common in med lists and patient pill bottles (e.g., acetaminophen)
• Brand Name: Familiar to patients (e.g., Tylenol)

Drug Cards Basics

• Generic and Brand Names
• Class: Defines drug's therapeutic use (e.g., antihypertensive, antipyretic)
• Mechanism of Action (MOA): How the drug achieves its effects in the body

Mechanism of Action

• Indication: When the drug should be used
  • E.g., Drugs that increase heart rate should be avoided if heart rate is already high
• Adverse Effects: Common side effects based on MOA
  • E.g., Increased heart rate may cause anxiety, palpitations
• Dose: Amount given to achieve the desired effect
• Route: Method of administration (e.g., IV, PO, IM)
• Special Considerations: Specific factors to consider when administering

Sympathetic vs. Parasympathetic Nervous System

• Sympathetic (Fight or Flight): Pupils dilate, heart rate and blood pressure rise, respiratory rate increases, digestion decreases
• Parasympathetic (Rest and Digest): Pupils constrict, heart rate and blood pressure drop, respiratory rate decreases, digestion increases

Key Terms

• Sympathomimetics: Mimic sympathetic nervous system, also called adrenergics (e.g., epinephrine)
• Sympatholytics: Opposite effect, induce parasympathetic response
• Parasympathomimetics: Turn on parasympathetic system
• Parasympatholytics: Inhibit parasympathetic system (e.g., atropine)
• Agonists: Drugs that turn on receptors
• Antagonists: Drugs that block receptors

Important Receptors

• Alpha 1: Vasoconstriction of blood vessels
• Beta 1: Affects heart (raises heart rate, increases contractility)
• Beta 2: Affects lungs (bronchodilation)
  • E.g., Albuterol and epinephrine for bronchodilation in asthma or anaphylaxis

Clinical Considerations

• Epinephrine: Agonist on alpha 1, beta 1, beta 2 (vasoconstriction, increased heart rate, bronchodilation)
• Atropine: Parasympatholytic, blocks vagus nerve to decrease parasympathetic activity and increase heart rate
• Beta Blockers: Antagonists that block beta receptors
  • Example: Not suitable for patients with asthma as they can cause bronchoconstriction

Summary

• Epinephrine: Sympathomimetic, activates alpha 1, beta 1, beta 2 receptors
• Atropine: Parasympatholytic, blocks vagus nerve, reduces parasympathetic response, increases heart rate

Applications

• Sympathomimetics: Used in emergency medicine to stimulate sympathetic responses
• Parasympatholytics: Used to manage bradycardia and other conditions by reducing parasympathetic activity

Note: For further information, follow the provided resources and videos.