Sample Page

Selenium disulfide is an inorganic compound with the approximate formula SeS₂. Both sulfur and selenium catenate^{[clarification needed]} form chains and rings readily, and mixtures of selenium and sulfur likewise give rise to numerous “alloys”.^[1] This compound is not an analogue of sulfur dioxide.

It is on the WHO Model List of Essential Medicines, the most important medications needed in a basic health system.^[2]

Medical uses

Selenium disulfide is sold as an antifungal agent in shampoos for the treatment of dandruff and seborrheic dermatitis associated in the scalp with Malassezia genus fungi.^[3][4][5] In the United States, a 1% strength is available over-the-counter, and a 2.5% strength is also available with a prescription. At the 2.5% strength, selenium disulfide is also used on the body to treat tinea versicolor, a type of fungal skin infection caused by a different species of Malassezia.

Chemical composition

Structure of 1,2,3-Se₃S₅

Selenium disulfide has a composition that approximates to SeS₂ and is sometimes called selenium sulfide. However, as used in proprietary formulations, it is not a pure chemical compound but is a mixture where the overall Se:S ratio is 1:2. The compounds are cyclic Se–S rings containing a variable number of S and Se atoms, Se_nS_8−n.^[1] Selenium disulfide can cause discoloration of the hair and alter the color of hair dyes. It may also discolor metallic jewellery.

Other selenium sulfides

Many selenium sulfides are known. A useful means for characterization is ⁷⁷Se NMR spectroscopy. Chalcogen ring interconversion pathways.^[6] Selenium monosulfide (SeS) is the only selenium compound so far identified as a carcinogen in animals.^[7] Selenium monosulfide, along with elemental selenium and sulfur, has been used in medicinal preparations in the past,^[8] causing confusion and contradiction^[9] as to exactly what form selenium is in any given topical preparation.^[10]

See also

• Zinc pyrithione, an antimicrobial agent used in some medicated shampoos
• Selsun Blue, a shampoo with selenium disulfide as its active ingredient
• Ketoconazole, another antifungal agent used in shampoos

References

Further reading

• Danby, FW; Maddin, WS; Margesson, LJ; Rosenthal, D (December 1993). “A randomized, double-blind, placebo-controlled trial of ketoconazole 2% shampoo versus selenium sulfide 2.5% shampoo in the treatment of moderate to severe dandruff”. Journal of the American Academy of Dermatology 29 (6): 1008–12. doi:10.1016/0190-9622(93)70282-x. PMID 8245236. 
• Grover, R. W. (1956). “Diffuse Hair Loss Associated with Selenium (Selsun) Sulfide Shampoo”. JAMA: the Journal of the American Medical Association 160 (16): 1397. doi:10.1001/jama.1956.02960510023006. 
• Givens, T. G.; Murray, M. M.; Baker, R. C. (1995). “Comparison of 1% and 2.5% Selenium Sulfide in the Treatment of Tinea Capitis”. Archives of Pediatrics and Adolescent Medicine 149 (7): 808–11. doi:10.1001/archpedi.1995.02170200098016. PMID 7795774. 
• Ransone, James W.; Scott, Norman M.; Knoblock, Edward C. (1961). “Selenium Sulfide Intoxication”. New England Journal of Medicine 264 (8): 384. doi:10.1056/NEJM196102232640806. 
• Laitinen, Risto S.; Pakkanen, Tapani A. (1987). “⁷⁷Se NMR spectroscopic characterization of selenium sulfide ring molecules Se_nS_8-n“. Inorganic Chemistry 26 (16): 2598. doi:10.1021/ic00263a010.