Clinical advantages of dual activity in allergic rhinitis.

Symptoms of allergic rhinitis include sneezing; itching of the eyes, nose, and throat; nasal obstruction; and rhinorrhoea; they may be seasonal or perennial, depending on the causative allergen. The major symptom of perennial allergic rhinitis is nasal obstruction. Sneezing and rhinorrhoea are often present, but are less troublesome than in seasonal allergic rhinitis. Symptom relief is a priority in allergic rhinitis because patients have a severely impaired quality of life. The nasal vascular system is complex. Histamine acts on postcapillary venules during both the immediate and late phase of reactivity and causes plasma extravasation. Other inflammatory mediators can also induce this reaction. Thus, histamine antagonists that also have some additional antiallergic properties have advantages in the treatment of allergic rhinitis. Mizolastine is a second-generation antihistamine that has been shown, in experimental studies, to possess 5-lipoxygenase inhibitory properties in addition to its H1-receptor antagonistic activity. In the treatment of seasonal allergic rhinitis, mizolastine 10 mg/day has been shown to be effective in reducing nasal and ocular symptoms. It has been shown to be significantly more effective than placebo with a greater percentage of responders. Another study has shown that symptoms of seasonal allergic rhinitis in mizolastine-treated patients were reduced more significantly than in cetirizine-treated patients on the second and third days of treatment. In perennial allergic rhinitis, mizolastine significantly improved symptoms of nasal obstruction compared with placebo and also significantly reduced nasal membrane colour, nasal secretions, and mucosal swelling as shown by rhinoscopy. These effects were maintained over a 5-month treatment period. Mizolastine has also been shown to be at least as effective as loratadine, and in one trial even superior in the treatment of perennial allergic rhinitis.