Lecture on Epinephrine and Atropine Mechanism of Action

Introduction

• Understanding the mechanism of action of drugs is crucial.
• Every drug has three names:
  • Chemical Name: Not commonly seen outside labs.
  • Generic Name: Frequently seen on medical lists and prescriptions.
  • Brand/Trade Name: Commonly recognized by patients.
• Example: Tylenol
  • Chemical: N/A
  • Generic: Acetaminophen
  • Brand: Tylenol

Drug Card Components

• Generic and Brand Name
• Class: Categorizes the drug (e.g., antihypertensive, antipyretic, sympathomimetic).
• Mechanism of Action (MOA): How the drug works in the body.
• Indications and Contraindications: When to use or avoid the drug.
• Adverse Effects: Potential negative reactions (e.g., increased heart rate, anxiety).
• Dosage and Route: Administration details (IV, IO, PO, IM).
• Special Considerations: Additional factors when administering.

Sympathetic vs. Parasympathetic Nervous System

• Sympathetic (Fight or Flight):
  • Increases: pupil dilation, heart rate, blood pressure, respiratory rate.
  • Decreases: digestion.
• Parasympathetic (Rest and Digest):
  • Opposite effects of sympathetic.

Key Terms

• Sympathomimetics:
  • Mimic sympathetic nervous system actions (also called adrenergics).
• Sympatholytics:
  • Induce parasympathetic effects by inhibiting sympathetic actions.
• Parasympathomimetics:
  • Activate parasympathetic system effects.
• Parasympatholytics:
  • Block parasympathetic actions (e.g., atropine).

Receptors

• Agonists: Activate receptors, causing physiological effects.
• Antagonists: Block receptors and inhibit effects.

Main Receptors

• Alpha-1: Causes vasoconstriction.
• Beta-1: Affects the heart (increases heart rate and contractility).
• Beta-2: Affects the lungs (bronchodilation).

Epinephrine vs. Atropine

• Epinephrine:
  • Agonist on alpha-1, beta-1, and beta-2.
  • Sympathomimetic: Increases heart rate, induces bronchodilation, and causes vasoconstriction.
• Atropine:
  • Parasympatholytic: Blocks vagus nerve, reducing parasympathetic activity, thus increasing heart rate.

Beta Blockers

• Purpose: Lower heart rate, blood pressure, and contractility.
• Can have crossover effects, affecting different beta receptors.
• Special consideration: Avoid in asthma patients due to potential bronchoconstriction.

Conclusion

• Epinephrine is a sympathomimetic agonist.
• Atropine is a parasympatholytic.
• Understanding drug mechanisms aids in proper application and avoiding adverse effects.