Respiratory System PHARMACOLOGY Dr Nasim Ullah Siddiqui

DRUGS USED TO TREAT ALLERGIC RHINITIS Rhinitis is an inflammation of the mucous membranes of the nose and is characterized by sneezing, itchy nose/eyes, watery rhinorrhea, and nasal congestion. An attack may be precipitated by inhalation of an allergen (such as dust, pollen, or animal dander).

DRUGS USED TO TREAT ALLERGIC RHINITIS The foreign material interacts with mast cells coated with IgE generated in response to a previous allergen exposure . The mast cells release mediators, such as histamine, leukotrienes, and chemotactic factors, that promote bronchiolar spasm and mucosal thickening from edema and cellular infiltration.

DRUGS USED TO TREAT ALLERGIC RHINITIS Combinations of oral antihistamines with decongestants are the first-line therapies for allergic rhinitis. Systemic effects associated with these oral preparations (sedation, insomnia, and, rarely, cardiac arrhythmias) have prompted interest in topical intranasal delivery of drugs.

DRUGS USED TO TREAT ALLERGIC RHINITIS Antihistamines (H1-receptor blockers) Antihistamines are the most frequently used agents in the treatment of sneezing and watery rhinorrhea associated with allergic rhinitis. H1-histamine receptor blockers, such as diphenhydramine, chlorpheniramine , loratadine , and fexofenadine, are useful in treating the symptoms of allergic rhinitis caused by histamine release.

DRUGS USED TO TREAT ALLERGIC RHINITIS Ocular and nasal antihistamine delivery devices are available over-the-counter for more targeted tissue delivery. Combinations of antihistamines with decongestants are effective when congestion is a feature of rhinitis.

DRUGS USED TO TREAT ALLERGIC RHINITIS Antihistamines differ in their ability to cause sedation and in their duration of action. In general, anticholinergic side effects of the first-generation antihistamines (dry eyes/mouth, difficulty urinating and/or defecating) are transient and may resolve in 7 to 10 days.

DRUGS USED TO TREAT ALLERGIC RHINITIS α-Adrenergic agonists Short-acting α-adrenergic agonists (“nasal decongestants”), such as phenylephrine, constrict dilated arterioles in the nasal mucosa and reduce airway resistance. Longer-acting oxymetazoline administered as an aerosol, these drugs have a rapid onset of action and show few systemic effects.

DRUGS USED TO TREAT ALLERGIC RHINITIS Oral administration results in longer duration of action but also increased systemic effects. Combinations of these agents with antihistamines are frequently used. The α-adrenergic agonists should be used no longer than several days due to the risk of rebound nasal congestion. α-Adrenergic agents have no place in the long-term treatment of allergic rhinitis.

DRUGS USED TO TREAT ALLERGIC RHINITIS Corticosteroids Corticosteroids, such as beclomethasone & triamcinolone, are effective when administered as nasal sprays. Topical steroids may be more effective than systemic antihistamines in relieving the nasal symptoms of both allergic and non allergic rhinitis. Treatment of chronic rhinitis may not result in improvement until 1 to 2 weeks after starting therapy.

DRUGS USED TO TREAT ALLERGIC RHINITIS Cromolyn Intranasal cromolyn may be useful, particularly when administered before contact with an allergen. To optimize the therapeutic effect of cromolyn, dosing should occur at least 1 to 2 weeks prior to allergen exposure. Due to a short duration of action, cromolyn requires multiple daily dosing.

REFRENCES LIPPINCOTTES PHARMACOLOGY THANK YOU