Agent nonsedating antihistamine

12 Sep

Cetirizine selectively inhibits histamine H1 receptor sites in blood vessels, GI tract, and respiratory tract, which in turn inhibits physiologic effects that histamine normally induces at H1 receptor sites. Bedtime dosing may be useful if sedation is a problem.Pseudoephedrine stimulates vasoconstriction by directly activating alpha-adrenergic receptors of the respiratory mucosa.Regular use of an intranasal steroid spray may be more appropriate for patients with chronic symptoms.Daily use of an antihistamine, decongestant, or both can be considered either instead of or in addition to nasal steroids.Histamine-1 receptors are also found in the brain and spinal cord.

Major metabolite of loratadine, which after ingestion is extensively metabolized to active metabolite 3-hydroxydesloratadine.Antihistamines are a class of agents that block histamine release from histamine-1 receptors and are mostly used to treat allergies or cold and flu symptoms, although some first-generation antihistamines may also be used for other conditions.Histamine-1 receptors are located in the airways, blood vessels and gastrointestinal tract (stomach and esophagus).Alternative to oral antihistamine to treat allergic rhinitis.One of the leukotriene receptor antagonists, montelukast (Singulair), has been approved in the United States for treatment of seasonal and perennial allergic rhinitis.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.They act on histamine receptors in the brain and spinal cord and in the rest of the body (called the periphery).They also act on muscarinic, alpha-adrenergic, and serotonin receptors.A limited number of studies comparing these agents suggest no major differences in efficacy.Only cetirizine causes drowsiness more frequently than placebo. Peak plasma levels reached within 1 h and half-life is about 8 h. Indicated for seasonal and perennial allergic rhinitis.