Cetirizine

Chemical Properties

white, crystalline powder

Uses

Cetirizine is a metabolite of the first-generation H1 antihistamine hydroxyzine. A reduced dosage (5 mg daily) is recommended in patients with chronic renal or hepatic impairment. Sedative side effects increase with dosages of cetirizine >10 mg per day.

Definition

ChEBI: A member of the class of piperazines that is piperazine in which the hydrogens attached to nitrogen are replaced by a (4-chlorophenyl)(phenyl)methyl and a 2-(carboxymethoxy)ethyl group respectively.

brand name

Zyrtec (Pfizer).

General Description

Cetirizine, (±)-[2-[4-[(4-chlorophenyl)phenylmethyl]- 1-piperazinyl]ethoxy]acetic acid (Zyrtec), is a racemic compound available as a white crystalline powder that is water soluble. Cetirizine is the primary acid metabolite of hydroxyzine, resulting from complete oxidation of the primary alcohol moiety. This compound is zwitterionic and relatively polar and thus does not penetrate or accumulate in the CNS. Before its introduction in the United States, cetirizine was one of the most widely prescribed H1-antihistamines in Europe.
Cetirizine is indicated for the temporary relief of runny nose, sneezing, itching of the nose or throat, and/or itchy, watery eyes caused by hay fever or other upper respiratory allergies. It also relieves itching caused by hives (urticaria), but it will not prevent hives or an allergic skin reaction from occurring.

Biological Activity

cetirizine, a second-generation antihistamine, is a major metabolite of hydroxyzine, and a racemic selective h1 receptor inverse agonist used in the treatment of allergies, hay fever, angioedema, and urticaria. cetirizine crosses the blood-brain barrier only slightly, reducing the sedative side-effect common with older antihistamines. it has also been shown to inhibit eosinophil chemotaxis and ltb4 release. at a dosage of 20 mg, boone et al. found that it inhibited the expression of vcam-1 in patients with atopic dermatitis. the levorotary enantiomer of cetirizine, known as levocetirizine, is the more active form. from wikipedia.

Clinical Use

Cetirizine, the acid metabolite from oxidation of the primary alcohol of the antihistamine hydroxyzine, is a widely used antihistamine. It has a long duration of action and is highly selective for H1 receptors. No cardiotoxicity has been reported, but some drowsiness occurs.