Shares of

Pfizer

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got a much-needed boost Wednesday as the world's No. 1 drugmaker said a new study showed its allergy drug Zyrtec outperformed

Sanofi-Aventis'

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Allegra.

Pfizer said that a study of almost 600 showed Zyrtec provided on average 14% greater symptom relief than Allegra for people who suffer from seasonal allergic rhinitis and documented ragweed sensitivity. The results applied to the entire period of five to 12 hours after patients took the drug.

The Pfizer-sponsored study was presented at the 62nd annual meeting of the American College of Allergy, Asthma and Immunology.

Zyrtec is a prescription antihistamine for the treatment of seasonal and perennial allergies, as well as chronic hives in adults and children, according to Pfizer.

Pfizer shares have slumped lately in the wake of

Merck's

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recall of its arthritis drug Vioxx because of health safety issues. The move has raised concerns about Pfizer's drugs Celebrex and Bextra, which come from the same family of drugs.

Shares rose 64 cents, or 2.3%, to $27.96.