Pharmacology Study Notes on Respiratory and Eye Disorders

Overview of the Upper Respiratory Tract

  • The upper respiratory tract starts from the mouth and nose, extending down to about halfway into the throat area.
  • Main functions include:
    • Protection via mucus and nose hairs, which trap particles to prevent them from entering the lungs.
    • Mucus warms and humidifies inhaled air.
    • Mast cells in the nasal mucosa contribute to inflammatory responses that cause runny noses during allergic reactions.

Allergic Rhinitis

  • Definition: Inflammation of the nasal passages (also referred to as nasal inflammation).
  • Common causes include allergies (e.g., pollen, also known as hay fever) and the common cold.
  • Symptoms may include:
    • Runny nose, watery eyes, and sneezing due to nasal inflammation.
  • Treatment options include:
    • Antihistamines (preventive measures) like Benadryl (diphenhydramine), Claritin (loratadine), Zyrtec (cetirizine), and Allegra (fexofenadine).
    • Decongestants (for acute symptoms).

Histamine and Its Role

  • Histamine: An inflammatory response mediator released during allergic reactions and found in different types (H1 in nasal inflammation, H2 in the stomach).
  • Antihistamines inhibit histamine release to reduce symptoms of allergies.
  • Common antihistamines:
    • Benadryl (diphenhydramine): First-generation, may cause drowsiness.
    • Claritin (loratadine): Less sedative, second-generation.
    • Zyrtec (cetirizine): Second-generation, may cause some drowsiness in sensitive individuals.
    • Allegra (fexofenadine), Xyzal (levocetirizine).

Generational Differences in Antihistamines

  • First Generation: More likely to cause sedation; example includes diphenhydramine.
  • Second Generation: Generally safer and less sedating; includes loratadine and cetirizine.
  • Common Side Effects of First-Generation Antihistamines: Drowsiness, anticholinergic effects (dry mouth, possible hypotension, especially in older adults).
    • Paradoxical Reaction: Children may exhibit excitability instead of drowsiness when taking diphenhydramine.

Intranasal Corticosteroids

  • Function: Used to reduce nasal inflammation.
  • Example medication: Fluticasone (Flonase).
  • Administration technique is important to prevent systemic absorption:
    • Blow nose, tilt head forward, spray towards the ear, and avoid blowing nose post-application.
  • Possible side effects include:
    • Nasal irritation, epistaxis (nosebleeds), headache, and nasopharyngitis.

Decongestants

  • Common Example: Pseudoephedrine (Sudafed), a nasal decongestant that also has systemic effects, may elevate blood pressure (not suitable for hypertensive patients).
  • Intranasal Decongestant: Oxymetazoline (Afrin) - reduces congestion but should not be used for more than 3-5 days to prevent rebound congestion.

Lower Respiratory Tract Overview

  • Includes structures from the bronchus to alveoli.
  • Gas exchange occurs in alveoli, crucial for oxygenation of the body.

Asthma Overview

  • Asthma: An inflammatory respiratory condition characterized by bronchospasms.
  • Symptoms include difficulty breathing and reduced airflow.
  • Quick relief medication: Albuterol (a beta-2 agonist) relaxes bronchial muscles.
  • Long-term medications: Corticosteroids, leukotriene modifiers, and mast cell stabilizers (e.g., montelukast/Singulair).

Beta-Agonists

  • Important in treating asthma and prevent bronchial constriction.
  • Common side effects: palpitations, increased heart rate, tremors, restlessness.
  • Caffeine and beta-blockers should be avoided when taking beta agonists.

Medications Overview for Patients with COPD and Asthma

  • COPD: Often results from smoking or inhaled irritants, and presents similarly managed to asthma with bronchodilators and corticosteroids.
  • Long-term treatment includes: beta-agonists (both short and long-acting), corticosteroids, and theophylline.

Eye Disorders Overview

Glaucoma

  • Increased intraocular pressure due to impaired aqueous humor outflow.
  • Types include:
    • Open-angle glaucoma: Common and asymptomatic until vision loss occurs.
    • Closed-angle glaucoma: Acute and requires immediate medical attention; might involve surgical intervention.
  • Medication treatments: Prostaglandin analogs (e.g., Lantanoprost).

Eye Drops and Administration

  • Administering eye drops: Head tilted, conjunctiva pulled down, avoid touching eye surfaces, and lacrimal duct pressure to minimize systemic absorption.
  • Myriasis induction (pupil dilation) and side effects: Blurred vision, photophobia from agents like atropine.
  • Commonly used: Artificial tears for dryness, phenylephrine for mydriasis, and beta blockers (ending in -olol) for glaucoma.

Important Patient Education Points

  • For antihistamines, monitor for sedation and avoid alcohol or CNS depressants.
  • For decongestants, teach about the risk of hypertension and avoiding prolonged use of nasal sprays.
  • For asthma medications, emphasize the correct inhaler technique and adherence to long-term therapies. Watch for tachycardia with beta-agonists.
  • Educate glaucoma patients on the importance of not missing scheduled eye exams and proper use of prescribed eye drops.
  • Discuss the importance of close monitoring for side effects and managing conditions with a healthcare provider's guidance.