Steroidal, Aldosterone Antagonists: Increased selectivity of 9α,11-epoxy derivatives†‡§

In the search for aldosterone antagonists with an optimal activity profile, twelve 9α, 11-epoxy-steroids were prepared and compared with their 9α, 11α -unsubstituted analogues in terms of steroid receptor binding in vitro and electrolyte excretion in vivo. Substitution of the parent structures by an epoxy group at positions 9α, 11 resulted in marginal effects on mineralocorticoid receptor binding and electrolyte excretion, but greatly reduced androgen and gestagen receptor binding. This finding is reflected in the largely lacking unwanted anti-androgenic and gestagenic side effects in animal models of the three most interesting 9α, 11 -epoxy-spirolactones 4(CGP 33033), 18(CGP 29245), and 25 (CGP 30083).