CLINICAL PHARMACOLOGY
When ketoconazole cream, 2% was applied dermally to intact or abraded skin of Beagle dogs for 28 consecutive days at a dose of 80 mg, there were no detectable plasma levels using an assay method having a lower detection limit of 2 ng/ml.
After a single topical application to the chest, back and arms of normal volunteers, systemic absorption of ketoconazole was not detected at the 5 ng/ml level in blood over a 72-hour period.
Two dermal irritancy studies, a human sensitization test, a phototoxicity study and a photoallergy study conducted in 38 male and 62 female volunteers showed no contact sensitization of the delayed hypersensitivity type, no irritation, no phototoxicity and no photoallergenic potential due to ketoconazole cream, 2%.
Microbiology
Ketoconazole is a broad spectrum synthetic antifungal agent which inhibits the in vitro growth of the following common dermatophytes and yeasts by altering the permeability of the cell membrane: dermatophytes: Trichophyton rubrum, T. mentagrophytes, T. tonsurans, Microsporum canis, M. audouini, M. gypseum and Epidermophyton floccosum; yeasts: Candida albicans, Malassezia ovale (Pityrosporum ovale) and C. tropicalis; and the organism responsible for tinea versicolor, Malassezia furfur (Pityrosporum orbiculare). Only those organisms listed in the INDICATIONS AND USAGE Section have been proven to be clinically affected. Development of resistance to ketoconazole has not been reported.
Mode of Action
In vitro studies suggest that ketoconazole impairs the synthesis of ergosterol, which is a vital component of fungal cell membranes.
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