Allergic Rhinitis

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Allergic Rhinitis

• Maianh Phung

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What is Allergic Rhinitis?

• Inflammation of the nasal mucous membrane
• An immune response to inhaled allergens

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Types of Immune Response

• Immediate Response (minutes)
• Histamine, tryptase, chymase, kinins, and
  heparin, leukotrienes, and prostaglanin D2
• Mucous membrane stimulated
• Vascular permeability increased
• Sensory nerves are stimulated
• Late Response (4-8 hours)
• Neutrophils, eosinophils, lymphocytes, and
  macrophages
• Inflammation continues
• Sources of rhinitus symptoms

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Symptoms of Allergic Rhinitis Are

• Sneezing
• Nasal Itching
• Rhinorrhea (running nose)
• Nasal Congestion
• May accompany with itching of eye, throat, and
  ears
• Systematic effects
• Fatigue
• Sleepiness
• Usually not life threatening

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General Approach to Treatment

• Avoidance
• Specific immunotherapy
• Specific allergen
• Desensitizing
• Pharmacotherapy
• Identify type of allergy rhinitis

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Two Types

• Seasonal Allergic Rhinitis
• AKA hay fever
• Caused by seasonal allergens such as pollen from
  flowers, trees, weeds, etc.
• Perennial Rhinitis
• Non-seasonal allergens
• Dust mites
• Animal dander
• Molds

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Diagnosis/Tests

• Detailed history
• Nature,duration, and course of symptoms
• Physical
• Facial features, eyes,ears, and nose
• Tests
• Allergy tests
• IgE count
• Eosinophil count

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Pharmacotherapeutic Options
 
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How Antihistamine was Discovered

• Sir Henry Dale discovered histamine (1907)
• Daniel Bovet and his team confirmed that
  histamine is responsible for allergic reactions
• Thymoxyethyldiethylamine (1937)
• Too toxic
• Bernard Halpern
• 1st nontoxic derivative of diethylamine (1942)

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How Does Antihistamine Work?

• Competitive antagonists to histamine

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Example
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Characteristics of

• First Generation Antihistamine
• Less selective
• Drowsiness
• Second and Third Generation Antihistamine
• Selects for peripheral H1 receptors
• Little drowsiness

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Side Effects

• Side effects through anticholinergic properties
• a- adrenergic receptors
• Norepinephrine
• Epinephrine
• Dopamine
• 5-HT receptors
• Seratonin

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Structures of
Dopamine
Histamine
Norepinephrine
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Adverse Side Effects

• 1st Generation
• Dizziness
• Tinnitus (ringing in ear)
• Blurred vision
• Euphoria
• Uncoordination
• Anxiety
• Insomnia
• Tremor
• Nausea
• Headache
• Hallucination
• Psychosis

• 2nd 3rd Gen.
• Fatigue
• Headache
• Nausea
• Dry mouth

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Structural Examples
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First Generation H1-receptor Antagonists

• Ethanolamines
• Diphenydramine (Benadryl)
• Akylamines
• Chlorpheniramine
• (Chlor-Trimeton)
• Piperzamines
• Vistaril
• (Hydraxyzine)
• Antivert (Meclizine)
• Tricyclics
• Promethazine (Phenergan)

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Second Generation H1-receptor Antagonists

• Certirizine (Zyrtec)
• Terfendadine (withdrawn)
• Loratadine (Claritin)

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Third Generation H-1 Receptor Antagonists

• Levocetirizine
• Desloratadine (Clarinex)
• Fexofenadine (Allegra)

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