Euclidean and fractal computer-assisted corneofungimetry: a comparison of 2% ketoconazole and 1% terbinafine topical formulations.

BACKGROUND: The corneofungimetry bioassay was designed as a unique model predicting the efficacy of topical and oral antifungals in dermatomycoses. OBJECTIVE: In this 2-step study performed in two groups of 15 volunteers, corneofungimetry was used to compare the effect of 5-day b.i.d. treatments with 2% ketoconazole and 1% terbinafine creams. METHODS: The bioassay was performed using 10 isolates of each of the 3 fungi Trichophyton rubrum, T. mentagrophytes var. interdigitale and Candida albicans put to grow on human stratum corneum. Controls were stratum corneum either untreated or enriched in propylene glycol contained in an unmedicated vehicle. Quantitative assessments were made using both Euclidean and fractal geometry parameters. RESULTS: In comparison with untreated stratum corneum, the fungitoxic activity of the 2% ketoconazole and 1% terbinafine formulations was obvious and similar against dermatophytes. By contrast, 2% ketoconazole was significantly more active against C. albicans than 1% terbinafine. The propylene-glycol-containing vehicle did not exhibit a significant effect upon the dermatophyte growth. Positive linear correlations were yielded between the extent area and the fractal dimension D of dermatophyte mycelia. By contrast, D appeared unrelated to the relative area of dermatophyte growth compared to controls. CONCLUSION: The combination of Euclidean and fractal analyses improves the information provided by the corneofungimetry bioassay. Creams containing 2% ketoconazole and 1% terbinafine appear equally effective against dermatophytes while the former is more potent against Candida albicans.