Studies in permeability of the middle ear mucosa. The feasibility of blocking inflammatory mediators.

The permeability and vasodilation of the middle ear mucosa was measured in dogs that were treated topically with histamine, bradykinin, prostaglandins, and bacterial endotoxin. All of these inflammatory mediators increased permeability and caused vasodilation. The antihistamine diphenhydramine hydrochloride, when given topically or intravenously, prevented the increase in permeability caused by histamine but had little or no effect on vasodilation. The antihistamine also reduced the permeability response to bradykinin. As antihistamines are not always useful in treating otitis media, other inflammatory mediators found in human effusions may be responsible for the condition. Because of our relative ignorance of the inflammatory process in otitis media, control of the process by drug treatment is not hopeful at present.