Which medications in the drug class Second-generation antihistamines are used in the treatment of Allergic Rhinitis?

Updated: Dec 26, 2018
  • Author: Javed Sheikh, MD; Chief Editor: Michael A Kaliner, MD  more...
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Answer

Second-generation antihistamines

Often referred to as the nonsedating antihistamines. They compete with histamine for histamine receptor type 1 (H1) receptor sites in the blood vessels, GI tract, and respiratory tract, which, in turn, inhibits physiologic effects that histamine normally induces at the H1 receptor sites. Some do not appear to produce clinically significant sedation at usual doses, while others have a low rate of sedation. [82, 83, 84] Other adverse effects (eg, anticholinergic symptoms) are generally not observed.

All are efficacious in controlling symptoms of allergic rhinitis (ie, sneezing, rhinorrhea, itching) but do not significantly improve nasal congestion. For this reason, some second-generation antihistamines are available as combination preparations containing a decongestant. They are often preferred for first-line therapy of allergic rhinitis, especially for seasonal or episodic symptoms, because of their excellent efficacy and safety profile. They can be used prn or daily.

Topical azelastine and olopatadine are nasal sprays antihistamines that effectively reduce sneezing, itching, and rhinorrhea but also effectively reduces congestion. [85, 86, 87] Used twice per day, especially when combined with a topical nasal corticosteroid, azelastine is effective at managing both allergic and nonallergic rhinitis.

The second-generation oral antihistamines currently available in the United States are cetirizine, levocetirizine, desloratadine, fexofenadine, and loratadine. A limited number of studies comparing these agents suggest no major differences in efficacy. Only cetirizine causes drowsiness more frequently than placebo. [84] Cetirizine, fexofenadine, and loratadine are also available in decongestant-containing preparations.

Cetirizine (Zyrtec)

Competes with histamine for H1 receptors in GI tract, blood vessels, and respiratory tract, reducing hypersensitivity reactions. Once-daily dosing is convenient. Bedtime dosing may be useful if sedation is a problem.

Levocetirizine (Xyzal)

Histamine1-receptor antagonist. Active enantiomer of cetirizine. Peak plasma levels reached within 1 h and half-life is about 8 h. Available as a 5-mg breakable (scored) tab. Indicated for seasonal and perennial allergic rhinitis.

Fexofenadine (Allegra Allergy, Mucinex Allergy)

Second-generation agent with a rate of sedation not significantly different from that of placebo. Competes with histamine for H1 receptors in GI tract, blood vessels, and respiratory tract, reducing hypersensitivity reactions. Available in qd and bid preparations.

Loratadine (Claritin, Loradamed, QlearQuil 24 hr Relief, Triaminic Allerchews, Alavert)

Selectively inhibits peripheral histamine H1 receptors. Tolerated well, with rate of sedation not significantly different from placebo.

Pseudoephedrine/loratadine (Alavert Allergy & Sinus, Claritin D-12 Hour Allergy & Congestion, Claritin-D 24 Hour Allergy & Congestion)

Selectively inhibits peripheral histamine H1 receptors. Tolerated well, with rate of sedation not significantly different from placebo.

Pseudoephedrine stimulates vasoconstriction by directly activating alpha-adrenergic receptors of the respiratory mucosa. Induces also bronchial relaxation and increases heart rate and contractility by stimulating beta-adrenergic receptors.

Tolerated well, with rate of sedation not significantly different from that of placebo. Some patients may notice anxiety or insomnia owing to pseudoephedrine component.

Pseudoephedrine/fexofenadine (Allegra-D 12 Hour, Allegra-D 24 Hour)

Fexofenadine is a nonsedating second-generation medication with fewer adverse effects than first-generation medications. Competes with histamine for H1 receptors on GI tract, blood vessels, and respiratory tract, reducing hypersensitivity reactions. Does not sedate.

Pseudoephedrine stimulates vasoconstriction by directly activating alpha-adrenergic receptors of the respiratory mucosa. Induces also bronchial relaxation and increases heart rate and contractility by stimulating beta-adrenergic receptors.

Desloratadine (Clarinex)

Relieves nasal congestion and systemic effects of seasonal allergy. Long-acting tricyclic histamine antagonist selective for H1-receptor. Major metabolite of loratadine, which after ingestion is extensively metabolized to active metabolite 3-hydroxydesloratadine.

Cetirizine/pseudoephedrine (Zyrtec D Allergy & Congestion)

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. Once-daily dosing is convenient. Bedtime dosing may be useful if sedation is a problem.

Pseudoephedrine stimulates vasoconstriction by directly activating alpha-adrenergic receptors of the respiratory mucosa. Induces also bronchial relaxation and increases heart rate and contractility by stimulating beta-adrenergic receptors.


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