Double-blind phase: The objective of the study was to evaluate the efficacy and safety of Bilastine 20 mg, compared to Cetirizine and placebo for the treatment of perennial allergic rhinitis.

Open-label Phase: The objective of this extension was to evaluate the long-term safety of Bilastine 20 mg during one year in the symptomatic treatment of perennial allergic rhinitis

Double-blind, randomized, placebo-controlled, parallel-group, international, multicenter study followed by an open label extension. Duration of the double-blind period was 28 days and the duration of the open label period was 12 additional months.

The primary efficacy variable of the double-blind period was the area under curve (AUC) of total symptoms scale (TSS) from baseline (defined as the mean of 6 last points of the patients' diary before randomization) to D28 visit according to the patient's assessment on reflective symptoms. 650 patients were included in the study and 614 completed the double-blind phase. Out of the 614 patients who completed the double blind period, a total of 513 patients started the open label period with Bilastine 20 mg (83.6%)

Inclusion Criteria:

• Patients of either sex aged from 12 to 70 years of age
• Patients with a documented clinical history of PAR for at least 2 years prior to the study inclusion
• Positive skin prick test for at least one of the following perennial allergens (house-dust mites, Dermatophagoides pteronyssinus or D. farinae, animal danders, dogs or cats, molds, etc.)
• Patients had to have a sum in the previous 6 assessments of the reflective nasal symptoms score equal to or greater than 30 (≥30 over 72). Additionally, at the time of randomization patients had to have positive symptomatology in instantaneous nasal symptoms equal or greater than 5 (≥5 over 12).
• Women of childbearing potential had to have a negative pregnancy test and had to use an effective contraceptive method.
• Provision of written informed consent to participate and willing to attend the required visits scheduled in the protocol
• The criteria to continue with the open label period included previous participation in the double blind period, eligibility for a long-term symptomatic treatment according to the investigator assessment and patient willingness to follow the treatment for one year.

Exclusion Criteria:

• Patients who have non-allergic rhinitis (vasomotor, infectious, drug-induced, etc.).
• Negative skin prick test (as defined in point 6.1.1.).
• Patients with nasal polyps or a significant deviation of the nasal septum as judged by the investigator as well as nasal intervention in the previous 6 months.
• Any other nasal illness that can interfere with the aim of the study.
• Patients who have acute or chronic sinusitis as judged by the investigator.
• Patients who are also diagnosed with SAR (seasonal allergic rhinitis), and the inclusion and follow-up during the double-blind phase in this study is concurrent with the pollen season.
• Immunotherapy (6 months): In case of patients under immunotherapy the treatment had to have started more than 6 months prior to the start of the study, the doses could not be modified during the study, and any doses could not be administered 24 hours before any study visit..
• Patients who are taking or have taken specified medications prior to randomisation in the study and have not complied with the specified washout period
• Severe concomitant disease that could interfere with treatment response (hepatic, renal, cardiovascular), electrocardiographic abnormalities, arrhythmia, recent acute myocardial infarction or neoplastic diseases