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ZYRTEC® Clinical Data

Starts working at hour 11,2

In 2 EEU studies*: ZYRTEC® worked 3 times faster than Claritin® (1 hour vs 3 hours)†1,2

*The environmental exposure unit (EEU) is an indoor chamber used to expose large groups of subjects to controlled levels of pollen comparable to those experienced outdoors during peak allergy season, and can be replicated regardless of time of year. The EEU is a validated, standard method of determining onset of action and duration of anti-allergic treatments.

ZYRTEC® 10 mg starts working at hour 1 and Claritin® starts working at hour 3, based on first dose on the first day of a 2-day study in 2 pollen chamber studies. Primary endpoint measured mean improvement from baseline in Major Symptom Complex (MSC) severity score. MSC symptoms included runny nose, sniffles, itchy nose, nose blows, sneezes, and watery eyes.

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References: 1. Day JH, Briscoe M, Widlitz MD. Cetirizine, loratadine, or placebo in subjects with seasonal allergic rhinitis: effects after controlled ragweed pollen challenge in an environmental exposure unit. J Allergy Clin Immunol. 1998;101(5):638-645. 2. Day JH, Briscoe M, Rafeiro E, Chapman D, Kramer B. Comparative onset of action and symptom relief with cetirizine, loratadine, or placebo in an environmental exposure unit in subjects with seasonal allergic rhinitis: confirmation of a test system. Ann Allergy Asthma Immunol. 2001;87(6):474-481.

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