Nystatin, sold under the brandname Mycostatin among others, is an antifungal medication. It is used to treat Candida infections of the skin including diaper rash, thrush, esophageal candidiasis, and vaginal yeast infections. It may also be used to prevent candidiasis in those who are at high risk. Nystatin may be used by mouth, in the vagina, or applied to the skin.Common side effects when applied to the skin include burning, itching, and a rash. Common side effects when taken by mouth include vomiting and diarrhea. During pregnancy use in the vagina is safe while other formulations have not been studied in this group. It works by disrupting the cell membrane of the fungal cells.Nystatin was discovered in 1950 by Rachel Fuller Brown and Elizabeth Lee Hazen. It was the first polyene macrolide antifungal. It is on the World Health Organizations List of Essential Medicines. It is available as a generic medication. It is made from the bacterium Streptomyces noursei. In 2019, it was the 222nd most commonly prescribed medication in the United States, with more than 2 million prescriptions. Medical uses
Skin, vaginal, mouth, and esophageal Candida infections usually respond well to treatment with nystatin. Infections of nails or hyperkeratinized skin do not respond well. It is available in many forms. When given parenterally, its activity is reduced due to presence of plasma.Oral nystatin is often used as a preventive treatment in people who are at risk for fungal infections, such as AIDS patients with a low CD4+ count and people receiving chemotherapy.
The structure of this active compound is characterized as a polyene macrolide with a deoxysugar D-mycosamine, an aminoglycoside. The genomic sequence of nystatin reveals the presence of the polyketide loading module (nysA), six polyketide syntheses modules (nysB, nysC, nysI, nysJ, and nysK) and two thioesterase modules (nysK and nysE). It is evident that the biosynthesis of the macrolide functionality follows the  polyketide synthase I pathway.Following the biosynthesis of the macrolide, the compound undergoes post-synthetic modifications, which are aided by the following enzymes: GDP-mannose dehydratase (nysIII), P450 monooxygenase (nysL and nysN), aminotransferase (nysDII), and glycosyltransferase (nysDI). The biosynthetic pathway is thought to proceed as shown to yield nystatin. The melting point of nystatin is 44 - 46 °C. History
Like many other antifungals and antibiotics, nystatin is of bacterial origin. It was isolated from Streptomyces noursei in 1950 by Elizabeth Lee Hazen and Rachel Fuller Brown, who were doing research for the Division of Laboratories and Research of the New York State Department of Health. Hazen found a promising micro-organism in the soil of a friends dairy farm. She named it Streptomyces noursei, after Jessie Nourse, the wife of the farms owner. Hazen and  Brown named nystatin after the New York State Health Department in 1954. The two discoverers patented the drug, and then donated the $13 million in profits to a foundation to fund similar research. Other uses
It is also used in cellular biology as an inhibitor of the lipid raft-caveolae endocytosis pathway on mammalian cells, at concentrations around 3 μg/ml.