Upper Respi

• Antihistamines


  (H1 blockers or H1-receptor antagonists)
• Antihistamines


  • Diphenhydramine
  • Chlorpheniramine
  • Clemastine fumarate
  • Azelastine
  • Cetirizine
  • Loratadine
• First-Generation Antihistamines


  Diphenhydramine, Chlorpheniramine, Clemastine fumarate
• Second-Generation Antihistamines


  Azelastine, Cetirizine, Loratadine
• Mechanism of Action of Antihistamines

  1. Compete with allergy-liberated histamine for H1-receptor sites

  2. Occasionally, a patient may develop a tolerance to the antihistaminic effects; changing to another antihistamine is usually effective when this occurs
• Therapeutic Outcome of Antihistamines

  Reduced symptoms of allergic rhinitis (e.g., rhinorrhea, lacrimation, itching, conjunctivitis)
• Side Effects of First-Generation Antihistamines


  • Drowsiness, dizziness, fatigue, and disturbed coordination
  • Skin rashes and anticholinergic symptoms such as: dry mouth, urine retention, blurred vision, and wheezing may occur
• Side Effects of Second-Generation Antihistamines


  • Little to no sedating effect
  • Fewer anticholinergic symptoms
• Antitussives


  Act on the cough-control center in the medulla to suppress the cough reflex
• Types of Antitussives


  • Nonopioid
  • Opioid
  • Combination preparations
• Opioid Antitussives


  • Codeine
  • Guaifenesin
  • Guaifenesin 200 mg and Codeine 9 mg
• Nonopioid Antitussives


  • Benzonatate
  • Dextromethorphan
• Expectorants


  • Guaifenesin
  • Dextromethorphan
• Mechanism of Action of Dextromethorphan


  1. Reduces the viscosity of tenacious secretions

  2. Acts as a nonopioid antitussive by changing a nonproductive cough to a less frequent, productive cough

  3. Acts directly on the MEDULLARY cough of the brain to depress the cough reflex, but it does NOT suppress respiration
• Decongestants


  Sympathomimetic amines that cause local vasoconstriction, shrinking of the nasal mucous membranes and a reduction in fluid secretion (runny nose)
• Mechanism of Action of Decongestants


  1. Shrinks the nasal mucosa by stimulating the alpha-adrenergic receptors in the nasal membranes

  2. Promotes drainage of the sinuses and improving airflow

  3. The advantage of oral decongestants is that they relieve nasal congestion for a longer period
• Expectorants


  Loosen bronchial secretions so they can be eliminated by coughing
• Guaifenesin


  The most common expectorant, used for the symptomatic relief of conditions characterized by mucus in the respiratory tract with a dry, nonproductive cough
• Mechanism of Action of Guaifenesin


  1. Acts by enhancing the output of respiratory tract fluid

  2. The increased flow of secretions decreases mucus viscosity and promotes ciliary action

  3. A combination of ciliary action and coughing then expels the phlegm from the pulmonary system