Wikipedia
Spirolactones, also known as steroid-17α-spirolactones, 17α-spirolactosteroids, or simply as 17α-spirolactones, are a group of steroidal compounds which are both spiro compounds and lactones and which feature these two structural properties combined in the form of a spirolactone ring at the 17α position. They are antimineralocorticoids, or antagonists of the mineralocorticoid receptor (which is activated predominantly by the mineralocorticoid steroid hormone aldosterone), and have been employed clinically as potassium-sparing diuretics. Some also possess progestogenic and/or antiandrogen properties, which have both contributed to side effects and been utilized for medical indications (e.g., spironolactone as an antiandrogen, and drospirenone as a progestin). The spirolactones were developed by G. D. Searle & Company in the 1950s and thereafter and were denoted as "SC" compounds (e.g., SC-9420 for spironolactone).
The spirolactones include the marketed drugs spironolactone (SC-9420; Aldactone), canrenone (SC-9376; Cantaren, Luvion), potassium canrenoate (SC-14266; Venactone, Soldactone), eplerenone (SC-66110; Inspra), and drospirenone (ZK-30595; Yasmin). Spirolactones that were not ever marketed include SC-5233, SC-8109, spiroxasone, prorenone (SC-23133), mexrenone (SC-25152, ZK-32055), dicirenone (SC-26304), spirorenone (ZK-35973), ZK-91587 (15β,16β-methylenemexrenone), mespirenone (ZK-94679), and ZK-97894 (7α-thiomethylmespirenone). Oxprenoate potassium (RU-28318) is not a spirolactone by definition but is a closely related antimineralocorticoid that was never marketed.
SC-5233, the propanoic acid lactone of 17β-hydroxyandrosterone, is the unsubstituted parent or prototype compound of the spirolactones, and is one of a few of the simplest members of the series along with SC-8109 (the 19-nor (19-demethyl) analogue of SC-5233) and canrenone (the 1,2-didehydro analogue of SC-5233). Spironolactone is a derivative of SC-5233 with a 7α-acetylthio group (that is, SC-5233 is 7-desthioacetylspironolactone).