11-Ketoprogesterone (brand name Ketogestin; former developmental code names Bio 66, U-1258), or 11-oxoprogesterone, also known as pregn-4-ene-3,11,20-trione, is a pregnane steroid related to cortisone (11-keto-17α,21-dihydroxyprogesterone) that was formerly used in veterinary medicine in the treatment of bovine ketosis. It was synthesized in 1940. The steroid has profound effects on carbohydrate metabolism and possesses activities associated with adrenal cortex hormones like cortisone. However, it is non-toxic even in high dosages, suggesting that it lacks conventional glucocorticoid activity, and it does not possess mineralocorticoid activity, unlike other adrenocortical hormones. 11-Ketoprogesterone may act through membrane glucocorticoid receptors.