Mechanism of Action

The mechanism of action of ketoconazole in the treatment of seborrheic dermatitis is not known.

Pharmacodynamics

The pharmacodynamics of Extina Foam has not been established.

Pharmacokinetics

In a bioavailability study, 12 subjects with moderate to severe seborrheic dermatitis applied 3 g of Extina Foam twice daily for 4 weeks. Circulating plasma levels of ketoconazole were < 6 ng/mL for a majority of subjects (75%), with a maximum level of 11 ng/mL observed in one subject.

Microbiology

Ketoconazole is an antifungal agent which inhibits the in vitro synthesis of ergosterol, a key sterol in the cell membrane of Malassezia furfur. The clinical significance of antifungal activity in the treatment of seborrheic dermatitis is not known.

CLINICAL STUDIES

The safety and efficacy of Extina Foam were evaluated in a randomized, double-blind, vehicle-controlled study in subjects 12 years and older with mild to severe seborrheic dermatitis. In the study, 427 subjects received Extina Foam and 420 subjects received vehicle foam. Subjects applied Extina Foam or vehicle foam twice daily for 4 weeks to affected areas on the face, scalp, and/or chest. The overall disease severity in terms of erythema, scaling, and induration was assessed at Baseline and week 4 on a 5-point Investigator's Static Global Assessment (ISGA) scale. Treatment success was defined as achieving a Week 4 (end of treatment) ISGA score of 0 (clear) or 1 (majority of lesions have individual scores for scaling, erythema, and induration that averages 1 [minimal or faint]) and at least two grades of improvement from baseline. The results are presented in Table 2. The database was not large enough to assess whether there were differences in effects in age, gender, or race subgroups.

Table 2: Efficacy Results

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