Mechanism of action olopatadine is a histamine h1 -receptor antagonist. indication indicated for the relief of the symptoms of seasonal allergic rhinitis in adults and children 6 years of age and older.dose: by the intranasal route only.- adults and adolescents 12 years of age and olderthe recommended dosage is two sprays per nostril twice daily.- children 6 to 11 years of agethe recommended dosage is one spray per nostril twice daily.