Pharmacology of Respiratory and Endocrine Systems

Posted on Apr 10, 2026 in Medicine & Health

Nervous System Overview

Sympathetic vs. Parasympathetic Nervous Systems

  • Sympathetic (Fight or Flight): Adrenergic, sympathomimetic, adrenaline. Effects: ↑ HR, relax lungs, ↓ saliva, relax bowels, contract sphincter, relax bladder.
  • Parasympathetic (Rest and Digest): Cholinergic, parasympathomimetic, acetylcholine. Effects: ↓ HR, contract lungs, ↑ saliva, contract bowels, relax sphincter, contract bladder.

Histamine and Respiratory Drugs

Histamine: Protection from foreign entities; causes allergic reactions.

  • Histamine 1: Drives respiratory/allergic responses.
  • Histamine 2: Regulates stomach acid (e.g., famotidine/Pepcid).

Respiratory drugs work by blocking or changing these switches to manage symptoms.

Antihistamines, Decongestants, and Cough Control

  • First-Generation Antihistamines (Central): e.g., diphenhydramine (Benadryl). Used for allergic rhinitis, pruritus, and urticaria. SE: Sedation, dry mouth, urine retention.
  • Second-Generation Antihistamines (Peripheral): e.g., loratadine (Claritin), cetirizine (Zyrtec). No sedation.
  • Decongestants: Intranasal steroids (e.g., -cort, -sone) or adrenergics (e.g., oxymetazoline, pseudoephedrine). Rebound effect (Rhinitis Medicamentosa): Dependence after 3-5 days.
  • Cough Control: Antitussives (e.g., codeine, dextromethorphan) suppress the cough reflex. Expectorants (e.g., guaifenesin) thin mucus.

Asthma and COPD Management

  • Asthma: Immune-mediated airway inflammation and bronchoconstriction.
  • COPD: Progressive, irreversible airflow restriction. Includes Chronic Bronchitis (blue bloater) and Emphysema (pink puffer).

Inhaler Delivery Systems

  • MDI (Metered Dose Inhaler): Uses propellant; requires hand-lung coordination. Use a spacer for children or elderly.
  • DPI (Dry-Powder Inhaler): Breath-activated; no spacer needed.

Respiratory Medications

  • SABA (Short-acting beta agonist): e.g., albuterol. Used for acute rescue.
  • LABA (Long-acting beta agonist): e.g., salmeterol. Used for maintenance (must combine with ICS).
  • Anticholinergics: e.g., ipratropium. Prevents bronchospasm.
  • Inhaled Corticosteroids (ICS): e.g., fluticasone. Anti-inflammatory. Rinse mouth after use to prevent thrush.

Anticoagulants and Tuberculosis

  • Anticoagulants: Heparin (IV/SQ), Warfarin (PO), and DOACs (e.g., apixaban).
  • Tuberculosis (RIPE Regimen): Rifampin, Isoniazid, Pyrazinamide, Ethambutol. Monitor for hepatotoxicity.

Endocrine: Thyroid and Diabetes

  • Thyroid: Levothyroxine for hypothyroidism. Monitor for signs of hyperthyroidism (tachycardia, insomnia).
  • Diabetes: Type 1 (insulin-dependent), Type 2 (insulin resistance).
  • Oral Meds: Biguanides (metformin) and Sulfonylureas (glipizide).
  • Insulin Types: Rapid, Short, Intermediate (NPH), and Long-acting (glargine).