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. It is postulated that the therapeutic effect of ketoconazole in seborrheic dermatitis is due to the reduction of M. ovale, but this has not been proven.

General

If a reaction suggesting sensitivity or chemical irritation should occur, use of the medication should be discontinued. Hepatitis (1:10,000 reported incidence) and, at high doses, lowered testosterone and ACTH induced corticosteroid serum levels have been seen with orally administered ketoconazole; these effects have not been seen with topical ketoconazole.

Carcinogenesis, Mutagenesis, Impairment of Fertility

A long-term feeding study in Swiss Albino mice and in Wistar rats showed no evidence of oncogenic activity. The dominant lethal mutation test in male and female mice revealed that single oral doses of ketoconazole as high as 80 mg/kg produced no mutation in any stage of germ cell development. The Ames' salmonella microsomal activator assay was also negative.

Pregnancy

Nursing Mothers

It is not known whether ketoconazole cream, 2% administered topically could result in sufficient systemic absorption to produce detectable quantities in breast milk. Nevertheless, a decision should be made whether to discontinue nursing or discontinue the drug, taking into account the importance of the drug to the mother.

Pediatric Use

Safety and effectiveness in children have not been established.

Cutaneous candidiasis, tinea corporis, tinea cruris, tinea pedis, and tinea (pityriasis) versicolor

It is recommended that ketoconazole cream, 2% be applied once daily to cover the affected and immediate surrounding area. Clinical improvement may be seen fairly soon after treatment is begun; however, candidal infections and tinea cruris and corporis should be treated for two weeks in order to reduce the possibility of recurrence.

Patients with tinea versicolor usually require two weeks of treatment. Patients with tinea pedis require six weeks of treatment.

Seborrheic dermatitis

Ketoconazole cream, 2% should be applied to the affected area twice daily for four weeks or until clinical clearing.

If a patient shows no clinical improvement after the treatment period, the diagnosis should be redetermined.

Store at 20° to 25°C (68° to 77°F) [see USP Controlled Room Temperature].