Seasonal allergic rhinitis, while called ‘hay fever’, is actually caused by airborne pollens from grasses and

4.11 Seasonal allergic rhinitis, while called ‘hay fever’, is actually caused by airborne pollens from grasses and

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and feathers commonly cause perennial allergic rhinitis. House dust mites are nearly universal in occurrence; a typical bed mattress may contain anything from 100,000 to 10 million mites. Ten per cent of the weight of a 2-year-old pillow may be composed of dead mites and their droppings. House dust mites are 0.2–

0.3 mm long and translucent. Because of this, they are essentially invisible to the unaided eye. The most common species of dust mites are: the European house dust mite, Dermatophagoides pteronyssinus from the family Pyroglyphidae; and the North American house dust mite, Der. farinae . Patients become allergic to the proteins in the mite faecal pellets. The examination of house dust mite extracts has indicated that over 30 different proteins can induce IgE antibody production in patients allergic to the house dust mite. There are, however, dominant specificities, especially the group 1 and 2 allergens, which can account for much of the allergenicity of extracts. Of the 19 denominated allergens, major IgE binding has been reported for group 1,

2, 3, 9, 11, 14, and 15 allergens. However, other causes can include perfumes, chemicals, cigarette smoke, cleansers, and cosmetics. The specific offenders vary by season. Weeds are usually a problem from late summer to

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spring, and outdoor moulds are largely

a late winter/early spring problem.

4.12 The new classification of allergic rhinitis (based on the allergic rhinitis and its impact on asthma [ARIA] guidelines) subdivides allergic rhinitis, in relation to the duration of the disease, into ‘intermittent’ or ‘persistent’ disease. The severity of allergic rhinitis is also classified as ‘mild’ or ‘moderate-severe’. (Adapted from Bousquet J et al. [2001]. J Allergy Clin Immunol, 108: s147–334.)

Physical examination helps to confirm the diagnosis, identify complications, and exclude other diagnoses (4.13). Long-standing obstruction due to adenoids leads to adenoid facies characterized by elongated face, open mouth, flattened malar eminences, pinched nostrils, raised upper lips, high-arch palate, and retracted jaws. In allergic rhinitis, the mucosa is pale and turbinates are hypertrophied (4.14). Nasal speculum examination might reveal purulent exudates and septal deviations. Anterior rhinoscopy is useful in ruling out co-existent nasal polyps and choanal atresia. Sinusitis may occur with long-standing disease and, rarely, infection may spread to the surrounding tissues (4.15).

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4.13 The allergic ‘salute’ refers to habitual rubbing of the nose due to constant irritation. It usually signifies an underlying allergic phenomena that is producing a profuse rhinorrhoea requiring frequent wiping. It is most marked in children.

4.14 Patient with chronic perennial allergic rhinitis. The nasal mucosa is pale and both turbinates are hypertrophied. (Courtesy of Dr SH Abid, Dow Medical University, Karachi, Pakistan.)

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4.15 Patient with chronic rhinitis and sinusitis. He presented with swelling of the lateral aspect of the nose and left- sided proptosis. Investigations revealed allergic fungal sinusitis involving nose and left paranasal sinuses. (Courtesy of Dr SH Abid, Dow Medical University, Karachi, Pakistan).

Treatment of allergic rhinitis

Pharmacological treatment of allergic rhinitis should take into account these primary considerations: the efficacy, safety, and cost-effectiveness of medications; the patient’s preference; and the objective of treatment. Since the progression and severity of allergic rhinitis are both correlated with environmental concentrations of the allergen causing the disease, allergen avoidance should be the first approach in the treatment of allergic rhinitis (4.16).

Pharmacological measures for the treatment of allergic rhinitis include antihistamines, corticosteroids, cromones,

Table 4.2 Therapeutic options in allergic rhinitis

Group Examples Remarks

First generation Diphenhydramine Significant antimuscarinic effects, potent antihistamines

Chlorpheniramine sedative, antimotion sickness Hydroxyzine

Moderate sedation and antimuscarinic effects Low sedation, mainly used for motion sickness

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Topical corticosteroids Beclomethasone Flurocarbon aerosol Triamcinalone Flunisolide Mometasone Budesonide Fluticasone

Decongestants Pseudoephedrine Rapid onset of action and continued usage Phenylpropanolamine

can lead to rhinitis medicamentosa. Phenylephrine

Cromones Sodium cromoglycate Used topically, safe in children and in pregnancy

Antileukotrienes Montelukast Useful in patients not tolerating topical Zileuton

corticosteroids

Anticholinergics Ipratropium bromide Used in individuals in whom rhinorrhea is the predominant symptom

Antihistamines are the mainstay of therapy, but are not effective in controlling nasal congestion. Topical corticosteroids are the most effective treatment in allergic rhinitis, and can be used as the first line of therapy. Antileukotrienes are only useful in mild disease, and their efficacy can be enhanced when used in combination with antihistamines

antileukotrienes, and decongestants (Table 4.2). Medica-tions used for rhinitis are most commonly administered intra-nasally or orally.

The ARIA (Allergic Rhinitis and its Impact on Asthma) workshop report has suggested a step-wise treatment of allergic rhinitis (4.17). Allergen immunotherapy is effective in the treatment of allergic rhinitis and benefits may persist for several years after treatment has stopped (Table 4.3). It can modify the progression of allergic disease and may prevent the development of new allergies. Newer routes of administration are currently being investigated, such as sublingual immunotherapy and the use of purified allergens, T-cell reactive peptides, humanized anti-IgE monoclonal antibodies, and plasmid DNA immunization.

Table 4.3 A sample immunotherapy schedul e

Dilution Concentration

Dosage (SQ-U) 1:1000 100 SQ-U/ml

Volume (ml)

1:100 1000 SQ-U/ml 0.2 200 0.4 400 0.8 800

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0.8 8000 1:1 100,000 SQ-U/ml