Adrenergic Drugs Overview

Adrenergic Drugs

• Adrenergic drugs mimic or enhance the effects of the sympathetic nervous system, specifically the actions of the neurotransmitters epinephrine and norepinephrine.
• These drugs act on adrenergic receptors throughout the body, leading to physiological responses such as increased heart rate, elevated blood pressure, bronchodilation, and heightened alertness.
• Commonly used to treat conditions like low blood pressure, asthma, and certain heart-related issues.

Distribution of Adrenergic Receptors

• α1: Arterioles (coronary, visceral, cutaneous), veins, internal sphincters, pupil dilator muscle.
• α2: Presynaptic membrane, pancreas, veins, adipose tissue, GIT sphincters, salivary glands.
• β1: Heart (SA node, atrial muscle, AV node, ventricles), kidney.
• β2: Arterioles (muscular), veins, bronchi (muscles), liver, pancreas, uterus, iris constrictor muscle.
• β3: Adipose tissue, urinary bladder.

Uses of Adrenergic Drugs in Surgery

• Hemostasis: Drugs like epinephrine and norepinephrine induce vasoconstriction to control bleeding during surgical procedures.
• Hypotension Treatment: Drugs like phenylephrine and dopamine can raise blood pressure and maintain perfusion during surgery.

Bronchodilation

• Adrenergic bronchodilators like albuterol and salmeterol are used to open up airways, facilitating breathing during surgeries, especially those involving the respiratory system.

Local Anesthesia Prolongation

• Adding adrenergic agonists like epinephrine to local anesthetics prolongs the duration of anesthesia by constricting blood vessels and slowing anesthetic agent absorption.

Side Effects of Adrenergic Drugs

• Increased heart rate, hypertension, and arrhythmias.

Antiadrenergic Drugs

• Antiadrenergic drugs inhibit the actions of the sympathetic nervous system and its neurotransmitters.
• They act on adrenergic receptors, leading to physiological effects like decreased heart rate, lowered blood pressure, and reduced heart contractility.
• Used to manage conditions such as hypertension, certain heart rhythm disorders, and anxiety.

Uses of Antiadrenergic Drugs in Surgery

• Blood Pressure Control: Beta blockers such as propranolol and metoprolol are used to manage and control high blood pressure during and after surgery.

Arrhythmia Management

• Antiadrenergic drugs like atenolol and esmolol are used to control and prevent irregular heart rhythms during surgical procedures.

Anxiety and Stress Reduction

• Antiadrenergic drugs can help manage pre-operative anxiety and stress, promoting a smoother surgical experience. Medications like propranolol can be used for this purpose.

Migraine Prevention

• Some antiadrenergic drugs, such as propranolol and timolol, are used to prevent migraines, which can be triggered by certain stimuli encountered during surgery.

Side Effects of Antiadrenergic Drugs

• Bradycardia (slow heart rate), hypotension (low blood pressure), and fatigue.