No abstract

N‐Substituted 4‐chloro‐5‐sulphamoylphthalimides showed diuretic activity in the rat. Reduction of the carbonyl group in the position para to the 5‐sulphamoyl group in the phthalimides produced even more active compounds. The relationship between potency and the nature of the N‐substituent was examined in 32 phthalimides and 10 reduced derivatives. Maximum potency was found in the N‐cycloalkyl and N‐cycloalkylmethyl compounds, one of which, 5‐chloro‐2‐cyclohexyl‐1‐oxo‐6‐sulphamoylisoindoline (clorexolone), was 300 times as active as chlorothiazide in the rat. This compound was examined in more detail in both the rat and the dog.