Sympathetic Nervous System (SNS) on Drugs Acting

Sympathetic Nervous System (SNS) Definition 

• The Sympathetic Nervous System (SNS) is a division of the autonomic nervous system responsible for the “fight or flight” response.
• Drugs acting on the SNS either stimulate (sympathomimetics) or inhibit (sympatholytic) its activity by targeting adrenergic receptors (α and β), affecting heart rate, blood pressure, bronchodilation, and metabolic processes.

Adrenergic Agonists (Sympathomimetics)

• Stimulate the SNS by acting on adrenergic receptors.

1. Alpha Agonists

   • ↑ Vasoconstriction, used for hypertension, nasal congestion.
   • Example:

2. Beta Agonists

   • Selective/non-selective, used for asthma, heart conditions.
   • Examples:
     • β1-selective (heart): Metoprolol (hypertension).
     • β2-selective (lungs): Albuterol (asthma).
     • Non-selective:

Adrenergic Antagonists (Sympatholytics)

• Block adrenergic receptors, inhibiting SNS effects.

1. Alpha Blockers

   • Used in hypertension, benign prostatic hyperplasia (BPH).
   • Example:

2. b) Beta Blockers

   • Used in hypertension, heart disease, anxiety.
   • Example: Propranolol.

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