rhinitis%20-%20allergic
RHINITIS - ALLERGIC
Allergic rhinitis is a symptomatic disorder of the nose secondary to IgE-mediated inflammation of the nasal membranes induced after exposure to allergens.
Major symptoms include nasal itching, watery rhinorrhea, nasal obstruction/congestion, sneezing and postnasal drainage.
Other symptoms include headache, conjunctival symptoms, eye pruritus, impaired smell and morning cough.
Symptoms can reverse spontaneous w/ or w/o treatment.

Principles of Therapy

  • Treatment of allergic rhinitis is based on the duration & severity of symptoms
  • A step-wise approach to treatment is recommended for adolescents & adults
  • Step down therapy as patient’s symptoms improve & step up when symptoms worsen
  • Similar therapeutic principles are applied in children; however, care should be taken to avoid the adverse effects of certain classes of drugs in the pediatric population
  • Combination/step-up therapy may be used in patients w/ inadequate response to monotherapy
    • Intranasal corticosteroids & oral antihistamines: has better symptom control than monotherapy
    • Oral antihistamines & oral decongestant or leukotriene modifiers: showed better symptom control compared to monotherapy
    • Intranasal corticosteroids & leukotriene modifiers: use should be limited if symptoms lessen or disappear w/ intranasal corticosteroids alone
    • Intranasal corticosteroids & intranasal antihistamines or intranasal Oxymetazoline: showed better efficacy than monotherapy
  • Drugs used for rhinitis are usually administered either orally or intranasally

Pharmacotherapy

Anticholinergics

  • Eg Ipratropium bromide
  • Block the muscarinic receptors of the seromucinous glands
  • Effectively controls watery rhinorrhea, but does not affect sneezing or nasal congestion, which precludes its use as a 1st-line medication
  • May be used together with intranasal corticosteroids or antihistamines in patients in whom rhinorrhea is the predominant symptom, or in whom rhinorrhea does not respond well to the other medications

Antihistamines

  • H1-receptor antagonists reduce nasal itching, sneezing & rhinorrhea, but are less effective for nasal obstruction
  • 1st-line treatment for mild-moderate intermittent & mild persistent rhinitis
  • Added to intranasal corticosteroids for moderate-severe persistent rhinitis uncontrolled by intranasal corticosteroid monotherapy

Nasal Antihistamines

  • Eg Azelastine, Olopatadine, Levocabastine
  • Rapid onset of action (<15-30 minutes)
  • Recommended in patients with seasonal, perennial, or episodic allergic rhinitis
  • Associated with clinically significant effect on nasal congestion
  • Effective at the site of administration
  • May be used for mild, organ limited disease or as an “as required” medication used together with a continuous one
  • As effective as oral antihistamines but require twice-daily dosing

Oral Antihistamines

  • With the advantage of relieving other allergic symptoms of other sites along w/ nasal symptoms
  • May be used to prevent symptoms associated with occasional allergy exposure
  • 2nd generation antihistamines are preferred over intranasal antihistamines
  • Use of 1st generation antihistamines should be limited; may reduce academic ability in school children
  • Onset of action occurs within 1 hour

Second-generation Oral Antihistamines

  • Eg Cetirizine, Desloratadine, Fexofenadine, Levocetirizine, Loratadine, Bilastine, Mequitazine
  • Should be considered as a 1st choice treatment
  • Have less undesirable CNS and fewer anticholinergic effects compared to 1st-generation antihistamines
  • Have little or no sedative effect at the recommended dosages

First-generation Oral Antihistamines

  • Eg Diphenhydramine, Chlorpheniramine, Clemastine
  • Use is limited by sedative and anticholinergic side effects and short half-life
  • May further impair cognitive functioning and school performance in children

Intraocular Antihistamines

  • May be used in patients with symptoms of ocular involvement (eg conjunctivitis)

Anti-Immunoglobulin E Antibody

  • Eg Omalizumab
  • Has been shown to be effective in reducing nasal symptoms and improving quality of life in patients with seasonal allergic rhinitis
  • Use for allergic rhinitis is currently limited in clinical setting until more evidence is available

Corticosteroids

  • Have a strong anti-inflammatory capacity by reducing cytokine & chemokine release

Intranasal Corticosteroids

  • Eg Beclomethasone, Budesonide, Ciclesonide, Flunisolide, Fluticasone, Mometasone, Triamcinolone
  • More efficacious than oral or topical nasal antihistamines in relieving symptoms of allergic rhinitis, especially nasal obstruction
  • Considered as 1st-line treatment in patients with moderate-severe and/or persistent symptoms
  • Onset of action is relatively slow (6-12 hours), with maximum efficacy developing after 2 weeks
  • Aqueous preparations are preferred because they are less irritating to the nasal mucosa
  • Studies have shown reassuring safety data of Fluticasone, Mometasone and Ciclesonide use on long-term growth of children
    • Generally, not associated with clinically significant systemic side effects if given in recommended doses 
  • In severe cases, nasal corticosteroids should be started 2 weeks before the start of the pollen season, then given regularly

Systemic Corticosteroids

  • May be used in rare conditions in severe patients unresponsive to other treatments and intolerant to intranasal corticosteroid
  • Prednisolone/Methylprednisolone should be administered in a short period of time

Decongestants

  • Promote vasoconstriction by acting on adrenergic receptors, thus relieving swelling of the nasal mucosa

Nasal Decongestants

  • Eg Oxymetazoline, Xylometazoline
  • Very effective in relieving nasal obstruction, & rhinorrhea
  • Because of the risk of rebound vasodilation (rhinitis medicamentosa) & atrophic rhinitis with prolonged use, their use should be limited to <5 days
  • Short courses may be used to immediately reduce severe nasal obstruction while giving other medications for allergic rhinitis

Cromoglicic acid

  • Less effective than antihistamines & intranasal corticosteroids
  • Compliance is often poor because of the need for frequent administration
  • May be considered in symptomatic treatment (nasopharyngeal itchiness, sneezing, rhinorrhea)
    • Intraocular cromones may be considered for the management of ocular symptoms (eg conjunctivitis)
  • Excellent safety profile may make it a suitable option for children and pregnant women

Oral Decongestants

  • Eg Pseudoephedrine, Ephedrine
  • Weaker effect on nasal obstruction than topical preparations, but do not cause rebound vasodilatation
  • Helps relieve nasal obstruction, rhinorrhea and ocular symptoms
  • Use may be considered in patients with severe allergic rhinitis who are unresponsive to oral antihistamines & intranasal corticosteroids
  • Use should be limited due to known adverse effects (insomnia, agitation, palpitation)

Leukotriene Receptor Antagonists

  • Eg Montelukast, Zafirlukast
  • Efficacy similar to oral antihistamines
  • Therapeutic option used either alone or in combination with antihistamines; not to be used as initial therapy
    • Based on some studies, the combination of Montelukast and antihistamine is more effective for nasal and ocular symptoms compared to placebo 
  • Preferred in patients with coexisting asthma
    • There is a reduction in beta-agonists use with administration of Montelukast

Saline Solutions

  • May be used as single or adjunctive agents in reducing the symptoms of allergic rhinitis
  • There is no difference in radiologic or symptomatic score when comparing isotonic with hypertonic saline, although hypertonic solutions have been shown to improve mucociliary clearance

Non-Pharmacological Therapy

Allergen Avoidance

  • The 1st step to symptom control in allergic rhinitis is identification and avoidance of the trigger allergens
  • Elimination of the allergen results in diminished severity of the disease and decreased requirement for medications
  • Identifying specific causal allergens by skin testing or laboratory testing may encourage patients to comply with allergen avoidance instructions
  • Effectiveness of avoidance will be measured by relief of the patient’s symptoms and by a decrease in the need for medications
  • In the majority of cases it is not possible to completely avoid allergens but these measures should be considered where appropriate

House dust mites

  • Major allergen found in houses
  • Wash sheets and blankets in hot water (60o C) every week
  • Use anti-mite covers in mattresses, beds and pillows
  • Vacuum-clean beds each week
  • For indoors, use of exhaust circulation-type cleaner is recommended
  • Clean furniture in the bedroom with damp rags

Pollen

  • Avoid going outdoors on days when pollen counts are high
  • Use of air conditioning
  • Keep doors and windows closed at home and when inside cars
  • Wear a mask and use glasses during heavy pollen dispersal period
  • Avoid wearing of woolen coats
  • Shake the dust off (eg suit and hair) before entering the house

Pets

  • Do not allow animals in the house
  • If this is not possible, exclude pets from bedroom or keep out of doors
  • Clean the rooms and improve the ventilation

Others

  • Discourage smoking by patient, household members and visitors
  • Minimize contact with irritants (eg perfumes, hair spray and other odors)
  • Reduce growth of molds in the home by decreasing humidity and eliminating sites for mold growth

Immunotherapy

  • Recommended for patients with moderate or severe persistent allergic rhinitis with inadequate response to usual pharmacologic therapy and allergen avoidance measures

Principles of Therapy

  • Repeated administration of specific allergens to patients with IgE-mediated conditions, to provide protection against allergic symptoms associated with exposure to these allergens
    • Most effective if secondary to pollen & dust mites; less effective if due to mold & animal dander
  • Specific immunotherapy is effective when optimally administered
  • Only treatment that may cause long term remission of rhinitis (3-5 years)
  •  Activates regulatory T cells, thereby altering humoral response to allergens by increasing CD8+ T cells & IL-10, & reducing IL-13 production 
  • Initial dose should be performed in a medical facility by a trained personnel
  • Recommended course is usually 4-5 years
  • Immunotherapy may be given to children and adults who have the following factors:
    • Evidence of specific IgE antibody to allergen
    • Any of the following:
      • Patient’s preference
      • Adherence to therapy
      • Required medications
      • Adverse effects to medications
      • Poor response to avoidance measures
      • Prevention of asthma in allergic rhinitis patients
      • Clinically diagnosed with both allergic rhinitis and asthma

Subcutaneous Immunotherapy

  • Indications for subcutaneous immunotherapy:
    • Inadequate control with medications
    • Patient refusal to receive pharmacotherapy, or to undergo treatment on a long-term basis
    • Intolerable or unacceptable adverse effects from medications
  • Should be performed by trained personnel
  • Efficacy for allergic rhinitis is comparable to that of nasal glucocorticoids 
  • Limited by frequent injection on regular basis and small risk of anaphylactic reaction

Sublingual Immunotherapy

  • A more viable treatment compared to SCIT as self-administration is encouraged with this form
  • Use should be limited to those who can tolerate systemic reactions & its treatment
  • Auto/self-injectable Epinephrine should be prescribed to all patients receiving SLIT
  • Has been associated with mild oral and gastrointestinal symptoms and less risk for anaphylaxis compared to SCIT
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