Effect of corticosteroid-antibiotic agents on granulation tissue in a murine model

To compare the effects of 3 commonly used ototopical corticosteroid-antibiotic agents, currently available for use in the treatment of inflammatory conditions of the external and middle ear, on granulation tissue in an established murine model of wound healing.

Twelve C57/BL6J mice.

Eight-millimeter wounds, created bilaterally on the dorsum of the mice, were treated with combinations of 0.3% ciprofloxacin and 0.1% dexamethasone (CiproDex), 0.3% tobramycin and 0.1% dexamethasone (TobraDex), 0.2% ciprofloxacin hydrochloride and 1% hydrocortisone (Cipro HC), or phosphate-buffered saline (n = 6 each) for 3 days (days 4-6) and then harvested on day 7. Wound sections were stained with hematoxylin-eosin, Gomori trichrome, and CD31. Extracellular matrix deposition was graded from 1-4, and neovascularization was assessed by counting the number of endothelial-lined vessel lumens per high-power field (HPF).

The mean +/- SEM grade of extracellular matrix deposition was lower in CiproDex- (1.7 +/- 0.2) and TobraDex- (2.0 +/- 0.2) but not Cipro HC-(2.9 +/- 0.3) treated wounds compared with control wounds (2.9 +/- 0.2) (P<.01). The mean +/- SEM number of vessel lumens per HPF was lower in CiproDex- (0.9 +/- 0.2 lumens/HPF), TobraDex- (1.5 +/- 0.3 lumens/HPF) and Cipro HC-(0.9 +/- 0.3 lumens/HPF) treated wounds compared with controls (3.3 +/- 0.5 lumens/HPF) (P<.01).

All 3 ototopical corticosteroid-antibiotic agents studied were equally effective at reducing neovascularization, although dexamethasone-based products were more effective at reducing extracellular matrix deposition. The results of this study suggest that ototopical agents containing dexamethasone may be more effective for the treatment of granulation tissue resulting from external and middle ear inflammatory conditions.