Which medications in the drug class H1 Antagonists (second-generation antihistamines) are used in the treatment of Acute Urticaria?

Updated: Mar 21, 2018
  • Author: Henry K Wong, MD, PhD; Chief Editor: Michael A Kaliner, MD  more...
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Answer

H1 Antagonists (second-generation antihistamines)

The newer second-generation antihistamines are nonsedating in most patients, with very few adverse effects reported. These agents are preferred for acute and chronic urticaria, with first-generation agents reserved for efractory cases. Commonly used H1 antagonists currently available in the United States are cetirizine, levocetirizine, desloratadine, loratadine, and fexofenadine.

Loratadine (Claritin, Alavert)

Loratadine selectively inhibits peripheral histamine H1 receptors. It is tolerated very well, with a rate of sedation that is not significantly different from that of placebo. The once-daily dosing makes it convenient.

Fexofenadine (Allegra)

Fexofenadine is a second-generation agent that is effective in urticaria. It is tolerated very well, with a rate of sedation that is not significantly different from that of placebo. Fexofenadine competes with histamine for H1 receptors on the GI tract, blood vessels, and respiratory tract, reducing hypersensitivity reactions.

Desloratadine (Clarinex)

Desloratadine is a long-acting tricyclic histamine antagonist selective for H1 receptors. It is a major metabolite of loratadine, which, after ingestion, is metabolized extensively to active metabolite 3-hydroxydesloratadine.

Levocetirizine (Xyzal)

Levocetirizine is a histamine1-receptor antagonist and an active enantiomer of cetirizine. Peak plasma levels are reached within 1 hour, and the half-life is about 8 hours. It is available as a 5-mg breakable (scored) tab and is indicated for uncomplicated skin manifestations of chronic idiopathic urticaria

Cetirizine (Zyrtec)

Cetirizine is a second-generation agent that is frequently used in urticaria. It acts by competitive inhibition of histamine at the H1 receptor. Once-daily dosing makes it convenient, and sedation occurs in approximately 10% of patients. Dosing qhs may be useful if sedation is a problem. Although the standard dose is 5-10 mg qd, some specialists increase this to 10 mg bid for chronic urticaria that is not responding to the usual FDA-approved maximum dose.


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