First non sedating antihistamine
Selective leukotriene receptor antagonist that inhibits the cysteinyl leukotriene (Cys LT 1) receptor.
Selectively prevents action of leukotrienes released by mast cells and eosinophils.
A limited number of studies comparing these agents suggest no major differences in efficacy.
Competes with histamine for H1 receptors on GI tract, blood vessels, and respiratory tract, reducing hypersensitivity reactions. Pseudoephedrine stimulates vasoconstriction by directly activating alpha-adrenergic receptors of the respiratory mucosa.
Relieves nasal congestion and systemic effects of seasonal allergy.
The second-generation antihistamines are nonsedating in most patients and are preferred as first-line therapy.
Few adverse effects are reported (cetirizine may cause drowsiness in as many as 10% of patients); therefore, many specialists prefer the use of second-generation agents for allergic rhinitis.
Some do not appear to produce clinically significant sedation at usual doses, while others have a low rate of sedation.
All are efficacious in controlling symptoms of allergic rhinitis (ie, sneezing, rhinorrhea, itching) but do not significantly improve nasal congestion.
Induces also bronchial relaxation and increases heart rate and contractility by stimulating beta-adrenergic receptors.
Fexofenadine is a nonsedating second-generation medication with fewer adverse effects than first-generation medications.
Most cases of allergic rhinitis respond to pharmacotherapy.
Patients with intermittent symptoms are often treated adequately with oral antihistamines, decongestants, or both as needed.
Caution patients taking medications with sedative effects about driving and operating heavy machinery.