indication

For treatment of tinea versicolor, tinea capitis, dandruff and seborrheic dermatitis of the scalp.

pharmacology

Selenium sulfide is an antifungal agent often used in shampoos for the treatment of dandruff and seborrheic dermatitis. Selenium sulfide is highly active in inhibiting the growth of P. ovale. It is also a proven cytostatic agent, slowing the growth of both hyperproliferative and normal cells in dandruff and seborrheic dermatitis. A 0.6% micronized form of selenium sulfide is also safe and effective for dandruff.

mechanism of action

Topical selenium sulfide may act by an antimitotic action, resulting in a reduction in the turnover of epidermal cells. It also has local irritant, antibacterial, and mild antifungal activity, which may contribute to its effectiveness. An antimitotic mechanism of action is suggested by data showing that selenium sulfide decreases the rate of incorporation of radioactively labeled thymidine into the DNA of dermal epithelial cells. The following organisms are generally considered susceptible to selenium sulfide in vitro: Malassezia furfur, Microsporum sp. including Microsporum audouinii and Microsporum canis, Pityrosporon sp., Trichophyton sp. including Trichophyton schoenleinii and Trichophyton tonsurans. Selenium sulfide has been shown to be sporicidal to T. tonsurans, the most common etiologic agent of tinea capitis. One in-vitro study demonstrated that 2.5% selenium sulfide was equivalent in sporicidal activity to both 1% and 2% zinc pyrithione.

toxicity

No documented reports of serious toxicity in humans resulting from acute ingestion of selenium sulfide, however, acute toxicity studies in animals suggest that ingestion of large amounts could result in potential human toxicity.

absorption

There is no substantial absorption through intact skin. Absorption has been reported in patients with open lesions on the scalp or in patients using a 1% cream on the back - a patient with scalp lesions that used selenium shampoos had a level of selenium sulfide as high as 32 μg/ml in her urine.