In vitro investigation of ceruminolytic activity of various otic cleansers for veterinary use

Knowledge of the ceruminolytic activity of commercially available ear cleansing products assists the practitioner to choose the best available product for specific clinical situations. The aim of this study was to quantify and compare the ceruminolytic activity of commercially available canine ear cleansers. For this purpose, the ceruminolytic activity of 13 ear cleansers was evaluated using a standardized synthetic cerumen (SSC) that mimics the composition and texture of canine cerumen. The test products were incubated with mild agitation for 20 min with 500 mg of SSC previously compacted at the bottom of a test tube. Ceruminolytic activity was then assessed by quantifying the SSC removed by decantation. This procedure was repeated five consecutive times on each tube simulating repeated applications in the canine ear canal. Good repeatability among replicates was found in this assay, allowing direct comparisons between products. The final percentage of SSC elimination ranged from none (similar to water), between 8 and 39% for three products and up to 90% for one product (P<0.001). It is concluded that, in the experimental conditions used in this study, only 1/13 products had significant ceruminolytic activity.