AHFS Class:

• Astringents, Anti-infective 84:04.16

Generic Name(s):

• Selenium Sulfide

Selenium sulfide is an anti-infective agent with cytostatic and antiseborrheic properties.

A 1% lotion of selenium sulfide is used to relieve the itching and flaking of the scalp associated with dandruff. A 1% shampoo or 2.5% lotion of the drug is used for the control of dandruff and of seborrheic dermatitis of the scalp. Dandruff usually responds to treatment, but tends to relapse if therapy is discontinued. If dandruff is left untreated, the resulting problems are those of appearance, and generally no medical disability will result. A 2.5% lotion of selenium sulfide has also been used for the treatment of tinea versicolor.

Administration

Selenium sulfide shampoo is applied topically to the hair and scalp. Selenium sulfide lotion is applied topically to the scalp as a shampoo or to the skin. The lotions and shampoo are intended for external use only. Patients should be directed to wash their hands thoroughly following use of the lotion. Patients should be advised to remove all jewelry before using the lotion, since selenium sulfide may damage it. Contact with the eyes should be avoided; if contact occurs, the affected eye(s) should be rinsed thoroughly with water.

Dosage

For the control of dandruff or seborrheic dermatitis of the scalp, 5-10 mL of the 2.5% selenium sulfide lotion is massaged into the wet scalp. The lotion should be allowed to remain on the scalp for 2-3 minutes following application. The scalp should then be rinsed thoroughly and application of the lotion and rinsing repeated. Initially, the lotion is usually applied as a shampoo twice weekly for 2 weeks. Subsequently, the frequency of application should be determined by response of the condition; for maintenance therapy, the 2.5% lotion is usually applied once every 1 or 2 weeks, or as infrequently as every 3 or 4 weeks in some patients.

A 1% lotion or shampoo of selenium sulfide is available over-the-counter for self-administration in the control of dandruff and/or dermatitis. For self-administration in the control of dandruff and/or dermatitis, a small amount of the 1% lotion or shampoo is massaged vigorously into the wet scalp. The scalp should then be rinsed thoroughly; application of the lotion and rinsing should be repeated. When used before or after bleaching, tinting, or permanent waving of the hair, the hair should be rinsed with cool water for at least 5 minutes following application of selenium sulfide lotion or shampoo. (See Cautions: Adverse Effects.) The 1% lotion or shampoo is usually applied once or twice weekly or as otherwise directed by a clinician. For maximum control, the shampoo should be used every time the patient usually shampoos their hair and scalp.

For the treatment of tinea versicolor, the 2.5% selenium sulfide lotion is applied topically to the affected areas of the skin; a small amount of water should be applied concurrently to form a lather. The lotion should be allowed to remain on the skin for 10 minutes following application; the skin should then be rinsed thoroughly. Application of the 2.5% lotion should be repeated once daily for 7 days.

Adverse Effects

Contact of preparations containing selenium sulfide with mucous membranes of the eye may cause irritation (e.g., stinging). Prolonged contact (e.g., overnight application) of preparations containing selenium sulfide with the skin may cause local irritation. When selenium sulfide is applied topically for the treatment of tinea versicolor, skin irritation may occur, especially in the genital areas and/or folds of the skin. Selenium sulfide lotions can cause rebound oiliness of the scalp; this effect has been reported following short-term application of a 2.5% lotion and following long-term application of a 1% lotion.

Discoloration of various shades of natural and dyed hair has occurred following topical application of selenium sulfide lotion. Hair discoloration does not appear to be a common occurrence, and usually is associated with poor or no rinsing following shampooing with the lotion. The manufacturers state that hair discoloration can be minimized by careful rinsing of the hair after treatment with the drug. Shampooing with a 2.5% lotion of the drug has also reportedly caused diffuse hair loss, which resolved 1-2 weeks following discontinuance of the drug. However, in one study comparing selenium sulfide lotion and a placebo lotion, there was no difference between the two preparations in their effect on the percentage of growing and resting hairs.

Selenium sulfide lotion has caused systemic toxicity following topical application to damaged skin. Following long-term topical use of the lotion in a woman with an open lesion on her scalp, systemic signs and symptoms of toxicity including tremors, severe perspiration, garlicky breath, pain in the lower abdomen, weakness, lethargy, loss of appetite, and occasional vomiting occurred. Signs and symptoms of toxicity resolved within 10 days after discontinuing the drug.

Precautions and Contraindications

Because of the risk of systemic toxicity, selenium sulfide lotions should not be applied to damaged skin (e.g., open lesions or acute inflammation or exudation of the scalp). Cutaneous sensitization of the scalp or adjacent areas has been reported; application of the drug should be discontinued if sensitization occurs. Since selenium sulfide may cause irritation of the genital areas and/or folds of the skin in patients with tinea versicolor, these areas should be rinsed thoroughly following topical application of the drug. Patients should be advised to avoid contact of the lotion with the eyes since irritation may occur; if the lotion does come in contact with the eye, the eye should be thoroughly rinsed with water. Patients should also be advised to discontinue the drug and contact a physician if the condition worsens or does not improve following regular use of selenium sulfide lotion as directed.

Selenium sulfide lotions are contraindicated in individuals with known hypersensitivity to the drug or any ingredient in the formulation.

Pediatric Precautions

Safety of selenium sulfide lotions in infants has not been established. A 1% selenium sulfide lotion should not be used in children younger than 2 years of age unless otherwise directed by a physician.

Carcinogenicity

There was no evidence of carcinogenicity following topical application of a 2.5% selenium sulfide lotion in mice; however, the results of this study are limited by the relatively short life span of the strain of mice tested. Other studies in mice using dermal application of 0.625 and 1.25% selenium sulfide lotions for 88 weeks did not reveal evidence of carcinogenic effects. Additional animal studies are currently under way.

Pregnancy and Fertility

Pregnancy

Animal reproduction studies have not been performed with selenium sulfide. It is also not known whether selenium sulfide can cause fetal harm when administered to pregnant women. Selenium sulfide should be used during pregnancy only when clearly needed and should generally not be used for the treatment of tinea versicolor during pregnancy.

Fertility

It is not known whether selenium sulfide can affect fertility.

Pharmacology

Selenium sulfide is an anti-infective agent having antibacterial and mild antifungal activity. The mechanism(s) of action of the drug in the treatment of dandruff and seborrheic dermatitis has not been fully determined. The drug is active against Pityrosporum ovale, a yeast-like fungus that is part of the normal flora of the scalp. Although it has been suggested that P. ovale may be associated with the development of dandruff and possibly seborrheic dermatitis, a definite causal relationship between this organism and these conditions has not been established. In one study, although the quantity of P. ovale was greater in patients with dandruff than in those without dandruff, it was concluded that no causal relationship existed and that the increased P. ovale may have been related to sebum materials trapped in the dandruff scales on which these organisms may feed. It has been suggested that selenium sulfide, when absorbed into epithelial tissue, is converted into selenium and sulfide ions, and that the selenium ions block the enzyme systems involved in the growth of epithelial tissue. Selenium sulfide has been shown to have a cytostatic (antimitotic) action resulting in a decreased rate of cell turnover in cells with normal or higher than normal turnover rates. The drug also has a local irritant effect.

Pharmacokinetics

Selenium sulfide does not appear to be absorbed percutaneously through intact skin following topical application to the scalp of a 1% lotion during usual shampooing conditions. The drug can be absorbed percutaneously when applied to damaged skin, and systemic toxicity may occur.

Chemistry and Stability

Chemistry

Selenium sulfide is an anti-infective agent with cytostatic and antiseborrheic properties. The drug occurs as a reddish brown to bright orange powder having not more than a faint odor and is practically insoluble in water and organic solvents. Selenium sulfide may be prepared by adding an aqueous solution of selenious acid to an aqueous solution containing a stoichiometric excess of hydrogen sulfide. Selenium sulfide contains 52-55.5% selenium. Selenium sulfide lotion is an aqueous, stabilized suspension of the drug. The lotion and shampoo may also contain a suitable buffer, detergent, and dispersing agent. Selenium sulfide lotion has a pH of 2-6.

Stability

Selenium sulfide lotion should be protected from heat. The lotion should be stored in a tight container at a temperature less than 40°C, preferably between 15-30°C; freezing should be avoided.

Additional Information

The American Society of Health-System Pharmacists, Inc. represents that the information provided in the accompanying monograph was formulated with a reasonable standard of care, and in conformity with professional standards in the field. Readers are advised that decisions regarding use of drugs are complex medical decisions requiring the independent, informed decision of an appropriate health care professional, and that the information contained in the monograph is provided for informational purposes only. The manufacturer's labeling should be consulted for more detailed information. The American Society of Health-System Pharmacists, Inc. does not endorse or recommend the use of any drug. The information contained in the monograph is not a substitute for medical care.