Effect of topical dexamethasone versus rimexolone on middle ear inflammation in experimental otitis media with...

The lipopolysaccharide (LPS)-induced chinchilla otitis media (OM) model was proven useful in screening anti-inflammatory agents for topical use. Both 1% rimexolone and 1% dexamethasone are effective in reducing the volume of middle ear effusion and mucosal thickness compared with control groups. Topical corticosteroid therapy was efficacious in reducing middle ear mucosal inflammation.

OM is one of the most common diseases in the pediatric population. Our previous studies have shown that treatment with systemic antibiotics and corticosteroids was more efficacious than antibiotics alone. The purpose of this study was to determine the effectiveness of topically applied corticosteroids on the outcome of OM. The long-term goal of this study was to develop a better method of OM treatment by demonstrating effectiveness of topically applied anti-inflammatory agents, such as corticosteroids, avoiding systemic side effects.

Three experimental groups were studied in chinchillas. OM with effusion was induced in all groups by injecting LPS. Group 1 consisted of controls in three subgroups as follows. Control-LPS alone, vehicle of dexamethasone (control-dexa), vehicle of rimexolone (control-rimex). Group 2 was treated with dexamethasone and included subgroups of separate concentrations of dexamethasone: 0.1% and 1% suspensions. Group 3 was treated with rimexolone and included subgroups of separate concentrations of rimexolone: 0.1% and 1% suspensions. A total of 58 animals were used: 18 for controls and 40 for experimental groups. All test substances (saline, control-dexa, control-rimex, dexamethasone and rimexolone, 200 microl) were injected at -2, 48 and 60 h; LPS was injected at 0 h. Animals were monitored by daily otomicroscopy. After 4 days, samples of middle ear effusion (MEE) were collected for analysis and temporal bones were harvested for histopathological studies.

At the end of 4 days, only in five ears (3/20 with 1% dexamethasone, 1/20 with 1% rimexolone, and 1/20 with 0.1% rimexolone) had the fluid diminished to the point of being unobservable. The volume of MEE, thickness of mucoperiosteum, and the degree of inflammation of middle ear mucosa with 1% dexamethasone and 1% rimexolone was significantly less compared with other groups.