October 05, 2020
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Spironolactone is a steroidal aldosterone blocker that was first reported in 1959 by John A. Cella and Robert C. Tweit at G. D. Searle & Co.1 (Skokie, IL). Aldosterone is an essential corticosteroid hormone that conserves sodium in the kidneys and other organs and regulates blood pressure. But it must be suppressed to treat fluid buildup in patients with heart failure, high blood pressure, and other conditions.

Cella and Tweit’s article was the second in a series on novel aldosterone blockers. In the first article, they reported compounds that worked best when administered parenterally. Spironolactone and similar compounds showed improved blocking activity when administered orally.

Spironolactone is on the World Health Organization's List of Essential Medicines. To this day, it is prescribed more than ten million times a year in the United States. The drug, however, has numerous adverse side effects, including high blood potassium, nausea, frequent urination, and dehydration. It also has estrogen-like effects, which can decrease sex drive in men. In recent years, this estrogenic property has been useful in feminizing hormone therapy for transgender women.

1. Searle was acquired by Monsanto in 1985 and was eventually absorbed into Pfizer.

Spironolactone hazard information

Hazard class*Hazard statement
Acute toxicity, oral, category 4H302—Harmful if swallowedChemical Safety Warning
Reproductive toxicity, category 1BH360—May damage fertility or the unborn childChemical Safety Warning

 *Globally Harmonized System of Classification and Labeling of Chemicals.
Explanation of pictograms.

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Spironolactone fast facts

CAS Reg. No.52-01-7
Pregn-4-ene-21-carboxylic acid, 7-(acetylthio)-17-hydroxy-3-oxo-, γ-lactone, (7α,17α)-
Empirical formulaC24H32O4S
Molar mass416.57 g/mol
AppearanceWhite to light tan crystalline powder
Melting Point134–135 ºCa
Water solubility 22 mg/L

a. Resolidifies and decomposes at 201–208 ºC.

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