<p>Cetirizine Hydrochloride is a potent H1 receptor antagonist without any significant anticholinergic and antiserotonic effects. At pharmacologically active dose levels, it has almost no drowsiness effect and does not cause behavioral changes. It inhibits the histamine-mediated early phase of the allergic reaction and also reduces the migration of inflammatory cells and the release of mediators associated with the late phase of the allergic reaction.<br />
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Pharmacokinetics: Cetirizine 10 mg achieves peak plasma concentrations of 257 mcg/L within one hour of administration (980 mcg/L in children). Food does not affect the extent of absorption, but it may slightly reduce the rate. Peak blood levels 0.3 micrograms/ml are reached between thirty &amp; sixty minutes after administration of 10 mg dose of Cetirizine. Its plasma half-life is approximately 11 hours. Absorption is very consistent from one subject to the next. Its renal clearance is 30 ml/minute and the excretion half-life is approximately nine hours.</p>