Adrenergic Drugs Overview

Adrenergic Drugs

• Adrenergic drugs mimic or enhance the sympathetic nervous system's effects, specifically the actions of epinephrine and norepinephrine.
• Adrenergic receptors are distributed as follows:
  • α1: Arterioles (coronary, visceral, cutaneous), veins, internal sphincters, iris dilator muscle
  • α2: Presynaptic membrane, pancreas, veins, adipose tissue, GIT sphincters, salivary glands
  • β1: Heart (SA node, atrial muscle, AV node, ventricles), kidney (β1 apparatus), adipose tissue
  • β2: Arterioles (muscular), veins, bronchi (muscles), liver, pancreas, uterus, iris constrictor muscle
  • β3: Adipose tissue, urinary bladder

Actions of Adrenergic Drugs in the Body

• Increasing heart rate
• Elevating blood pressure
• Bronchodilation
• Heightened alertness

Uses of Adrenergic Drugs in Surgery

• Hemostasis: Used to induce vasoconstriction and control bleeding during surgical procedures (e.g., epinephrine, norepinephrine)
• Hypotension Treatment: Used to raise blood pressure in cases of hypotension during surgery (e.g., phenylephrine, dopamine)

Adrenergic Bronchodilation

• Bronchodilators like albuterol and salmeterol open airways.
• Facilitate breathing during surgeries, especially those involving the respiratory system.

Local Anesthesia Prolongation

• Adding adrenergic agonists (e.g., epinephrine) to local anesthetics prolongs anesthesia by constricting blood vessels and slowing anesthetic absorption.

Side Effects of Adrenergic Drugs

• Increased heart rate
• Hypertension
• Arrhythmias

Antiadrenergic Drugs

• Inhibit the actions of the sympathetic nervous system and its neurotransmitters (e.g., epinephrine, norepinephrine).
• Act on adrenergic receptors, leading to:
  • Decreased heart rate
  • Lowered blood pressure
  • Reduced heart contractility
• Used to manage conditions like hypertension, certain heart rhythm disorders, and anxiety.

Uses of Antiadrenergic Drugs in Surgery

• Blood Pressure Control: Used to manage and control high blood pressure during and after surgery (e.g., beta-blockers like propranolol and metoprolol).

Antiadrenergic Drugs in Arrhythmia Management

• Used to control and prevent irregular heart rhythms during surgical procedures.
• Examples include atenolol and esmolol, used to manage tachycardia.

Antiadrenergic Drugs in Anxiety and Stress Reduction

• Help manage pre-operative anxiety and stress, promoting a smoother surgical experience for the patient.
• Medication like propranolol can be used for this purpose.

Antiadrenergic Drugs in Migraine Prevention

• Some antiadrenergic drugs (e.g., propranolol, timolol) are used to prevent migraines, which may be triggered by stimuli during surgery.

Side Effects of Antiadrenergic Drugs

• Bradycardia
• Hypotension
• Fatigue