CP

• Antigen

  Any substance that induces the immune system to produce antibodies against it
• Auto antigen

  Gumagawa ng sariling antigen na nilalabanan yung immune system
• Antigen


  WBC (lymphocytes) → IgE → trigger si mast cell mag produce ng histamine
• 4 TYPES OF HYPERSENSITIVITY REACTION (ACID)

  • Type 1: Allergic Reaction (Immediate hypersensitivity)
  • Type 2: Cytotoxic reaction
  • Type 3: Immune complex reaction
  • Type 4: Delayed hypersensitivity
• Type 4 Hypersensitivity

  • Cell-mediated immunity
  • Mediated by T-cells rather than antibodies
  • Days- weeks
  • Examples: Mantoux test (PPD), nickel allergy, SJS, poison ivy
• Allergy occurs because of certain pollutants
• Type 1 Hypersensitivity

  • IgE mediated release of histamine, mast cells, and basophils
  • Reaction within 1 hour
  • Examples: Bee sting, latex allergy, medications (penicillin), urticaria, anaphylaxis, atopy
• Type 3 Hypersensitivity

  • Involves circulating IgG and IgM immune complex that deposits in postcapillary venules
  • 1-3 weeks
  • Example: SLE, Serum sickness
• Types of Allergic Rhinitis

  • Seasonal
  • Persistent (formerly called “perennial”)
• Pathophysiology of Allergic Rhinitis

  1. Airborne allergens enter the nose during inhalation and are processed by lymphocytes, which produce antigen-specific IgE, sensitizing genetically predisposed hosts to those agents

  2. On nasal reexposure, IgE bound to mast cells interacts with airborne allergens, triggering release of inflammatory mediators

  3. Immediate reaction occurs within seconds to minutes, resulting in rapid release of preformed and newly generated mediators from the arachidonic acid cascade

  4. Mediators of immediate hypersensitivity include histamine, leukotrienes, prostaglandin, tryptase, and kinins which cause vasodilation, increased vascular permeability, and production of nasal secretions

  5. Late-phase reaction may occur 4 to 8 hours after initial allergen exposure due to cytokine release from mast cells and thymus-derived helper lymphocytes, causing persistent chronic symptoms including nasal congestion
• Antigen vs allergen

  • Antigen - foreign substance pa lang
  • Allergen - capable of causing allergic reactions
• Allergic rhinitis involves inflammation of nasal mucous membranes in sensitized individuals when inhaled allergenic particles contact mucous membranes and elicit a response mediated by immunoglobulin E (IgE)
• Type 2 Hypersensitivity

  • Involves IgG and IgM bound cell surface antigens
  • Hours to days
  • Examples: Hemolytic reactions with medications, graft rejections
• Types of Antigen

  • Exogenous: Antigens that enter the body, trapped in antigen-presenting cells (Macrophages/ Dendritic cells) such as microorganisms (bacteria, pollens, etc.), allergens
  • Endogenous: Body’s own cell or sub-fragments like blood group antigen, histocompatibility leucocyte antigen
  • Auto antigen: normal proteins or complexes that are recognized by the immune system of someone with an autoimmune condition like thyroglobulin
• Allergen


  4 to 8 hours after exposure causes red, itchy, and watery eyes, sneezing, congestion, runny nose, itchy or so
• Inflammation occurs in the nose area
• Diagnosis

  1. Medical history including symptoms, environmental factors, previous therapy, medications, nasal injury or surgery, family history

  2. Allergy testing to determine if rhinitis is caused by immune response to allergens, commonly using immediate-type hypersensitivity skin tests or percutaneous testing
• Allergen symptoms

  • Red, itchy, and watery eyes
  • Sneezing, congestion, and runny nose
  • Itchy or sore throat, cough and postnasal drip
  • Itchy ears and buzzing sound
• Symptoms of rhinitis

  • Clear rhinorrhea, sneezing, nasal congestion, postnasal drip, allergic conjunctivitis, and pruritic (itching) eyes, ears, or nose
• Pharmacologic Therapy

  1. H1 Receptor Blocker: Histamine H1-receptor antagonists bind to H1 receptors without activating them, preventing histamine binding and action

  2. Decongestant: Sympathomimetic agents that act on adrenergic receptors in nasal mucosa to produce vasoconstriction, shrink swollen mucosa, and improve ventilation

  3. Nasal Corticosteroid: Intranasal corticosteroids relieve sneezing, rhinorrhea, pruritus, and nasal congestion with minimal side effects, reducing inflammation by blocking medi
• Patients may complain of loss of smell (anosmia) or taste, with sinusitis or polyps the underlying cause in many cases. Postnasal drip with cough or hoarseness can be bothersome
• This inflammatory response causes persistent chronic symptoms, including nasal congestion
• Classification based on Frequency

  • Intermittent: Response lasting <4 days/ week or <4 weeks per year
  • Persistent: Response lasting >4 days/week or >4 weeks/year
  • Mild: Symptoms that do not interfere with quality of life
  • Moderate to severe: Symptoms that interfere with quality of life such as sleep disturbance and work performance
• Clinical Presentation

  1. Seasonal (hay fever) allergic rhinitis occurs in response to specific allergens (pollen from trees, grasses, and weeds) present at predictable times of the year (spring and/or fall) and typically causes more acute symptoms

  2. Persistent allergic rhinitis occurs year-round in response to nonseasonal allergens (eg, dust mites, animal dander, and molds) and usually causes more subtle, chronic symptoms

  3. Many patients have a combination of both types, with symptoms year-round and seasonal exacerbations
• In children, physical examination may reveal dark circles under the eyes (allergic shiners), a transverse nasal crease caused by repeated rubbing of the nose, adenoidal breathing, edematous nasal turbinates coated with clear secretions, tearing, and periorbital swelling
• The radioallergosorbent test (RAST) can detect IgE antibodies in the blood that are specific for a given antigen, but it is less sensitive than percutaneous tests
• Ipratropium bromide

  Useful in persistent allergic rhinitis, exhibits antisecretory properties when applied locally, provides symptomatic relief of rhinorrhea
• Severe reactions to subcutaneous immunotherapy are treated with epinephrine, antihistamines, and systemic corticosteroids
• Cromolyn Sodium

  1. Available as a nonprescription nasal spray for symptomatic prevention and treatment of allergic rhinitis

  2. Prevents antigen-triggered mast cell degranulation and release of mediators, including histamine
• Immunotherapy

  1. Administering doses of antigens responsible for eliciting allergic symptoms into a patient with the intent of inducing tolerance to the allergen when natural exposure occurs

  2. Subcutaneous immunotherapy involves giving very dilute solutions initially once or twice weekly

  3. Sublingual immunotherapy is available for ragweed and certain grass allergies
• PHCP - Clinical Pharmacy and Pharmacotherapeutics

  1. For seasonal rhinitis, treatment should be initiated just before the start of the offending allergen’s season and continue throughout the season

  2. For persistent rhinitis, effects may not be seen for 2 to 4 weeks; antihistamines or decongestants may be needed during this initial phase of therapy
• Leukotriene, which Montelukast acts on, comes from the arachidonic pathway and causes bronchoconstriction
• Severe reactions to subcutaneous immunotherapy are rare and include generalized urticaria, bronchospasm, laryngospasm, vascular collapse, and death from anaphylaxis
• Nasal Corticosteroid

  1. Relieve sneezing, rhinorrhea, pruritus, and nasal congestion with minimal side effects

  2. Reduce inflammation by blocking mediator release, suppressing neutrophil chemotaxis, causing mild vasoconstriction, and inhibiting mast cell-mediated, late-phase reactions
• Non-pharmacologic treatment includes avoiding offending allergens, removing pets from the home, reducing exposure to dust mites, and preventing poor air quality in homes
• Montelukast

  1. Approved for treatment of persistent allergic rhinitis in children as young as 6 months and for seasonal allergic rhinitis in children as young as 2 years

  2. Effective alone or in combination with an antihistamine

  3. Considered third-line therapy after antihistamines and intranasal corticosteroids
• The most common side effect of Cromolyn Sodium is local irritation (sneezing and nasal stinging)
• Reasons for the use of edrine in many non-prescription antihistamine-decongestant combination products

  • Legal restrictions on pseudoephedrine sales
• Adverse reactions with subcutaneous immunotherapy include mild local adverse reactions like induration and swelling at the injection site
• Common reactions to sublingual immunotherapy are pruritus of the mouth, ears, and tongue; throat irritation; and mouth edema