Primary Objectives:

• To demonstrate that the aggravation of seasonal allergic rhinitis symptoms in the presence of pollutants is observed using an Environmental Exposure Unit.
• To evaluate the efficacy of fexofenadine hydrochloride in subjects suffering from seasonal allergic rhinitis symptoms aggravated in the presence of diesel exhaust particulates.

Secondary Objective:

To evaluate the safety of a single dose of fexofenadine hydrochloride 180 mg.

The total study duration per subject is expected to last up to 4.5 months, depending on the timing of the screening visit.

Inclusion criteria:

• Males or females between the ages of 18 and 65 suffering from seasonal allergic rhinitis provoked by ragweed pollen.
• Having a 2-year history of seasonal allergic rhinitis with positive skin prick test to ragweed allergen at screening with a wheal diameter at least 3 mm larger than that produced by the negative control.
• Subjects with antecedents of allergic seasonal allergic rhinitis symptom aggravation when exposed to pollen and air pollutants (i.e., cleaning products, diesel, paints).
• Subjects having a total nasal symptom score ≥3 in Period 1 (Visit 2).

Exclusion criteria:

• History of anaphylaxis to ragweed pollen.
• History of asthma. Mild asthmatics treated only with pro re nata short-acting beta2-agonists, 2 doses or less per week can be enrolled.
• History of chronic sinusitis.
• History of systemic disease affecting the immune system.
• Evidence of any active or suspected bacterial, viral, fungal or parasitic infections within 30 days prior to allergen challenge.
• Any history of Grade 4 anaphylaxis due to any cause as defined by the Common Terminology Criteria for Adverse Event grading criteria ("Life threatening consequences: urgent intervention indicated").
• Presence or history of drug hypersensitivity to fexofenadine.
• Subjects receiving build-up injections of pollen allergen immunotherapy (those on stable maintenance dosing can be included).
• Subjects taking any forbidden treatments/nutriments.

The above information is not intended to contain all considerations relevant to a patient's potential participation in a clinical trial.

Qualified researchers may request access to patient level data and related study documents including the clinical study report, study protocol with any amendments, blank case report form, statistical analysis plan, and dataset specifications. Patient level data will be anonymized and study documents will be redacted to protect the privacy of trial participants. Further details on Sanofi's data sharing criteria, eligible studies, and process for requesting access can be found at: https://vivli.org