Antihistamine effects on experimental middle ear inflammatory model.

Allergy is thought to be one of the etiologic factors in otitis media. The purpose of this study was to determine the histopathologic effects of H1 histamine receptor antagonists in an experimental histamine-induced middle ear inflammation model. In group A (20 rabbits), histamine challenge followed a 3-day intramuscular pretreatment with a single dose of 0.1 ml hydroxyzine hydrochloride (50 mg/ml) per day. In group B (20 rabbits), histamine challenge followed a 3-day pretreatment with a single dose 1.2 mg desloratadine per day orally. In group C (20 rabbits), histamine challenge followed a 3-day pretreatment with a single dose 1.2 mg levocetirizine per day orally. On the fourth day after baseline otomicroscopy 0.5 ml histamine 20 mg/ml was injected transtympanically on the right. Middle ear mucosa was removed and the following parameters were assessed: edema, vascular dilatation and congestion, inflammation, acute inflammatory component, presence of eosinophils, activity of the inflammation and fibrosis. A semi-quantitative grading system of 0-3 was used for grading of all parameters and statistical analysis performed by using the Mann-Whitney non-parametric test. Group A mucosae showed lower grades of all the parameters evaluated compared with those of group B. Histopathology of the mucosae of group C showed lower grade of inflammation compared with group B with significant statistical difference for the seven parameters tested. Our data validate the use of antihistamines in the treatment of refractory OME of allergic origin. Oldest H1 antagonists can be replaced by the newest agents who counteract successfully histamine effects, without any interactions or adverse effects from central nervous system.