Spirobutyrolactones

Thiazide diuretics, typified by hydrochlorothiazide, tend to cause excess urinary excretion of potassium over sodium ion, upsetting the normal semm concentration of these ions. Administration of spirobutyrolactones, on the other hand, leads to a more physiological balance of those ions in urine. As a result, these dmgs are often termed potassium-sparing diuretics. The pioneer orally active spirobutyrolactone (37-2) is still on the market as a diuretic under the generic name spironolactone and the trade name Aldactone. Now that the patent has expired, the agent is now sold as a generic dmg by many manufacturers, and as a result is available under a plethora of trade names. 

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A small set of steroids prepared from androstanes feature a spirobutyrolactone at C17. These agents act as antagonists of aldosterone, the highly oxygenated steroid that controls serum electrolytes and blood volume. The antagonist action of the spirolactones is manifested as diuretic and antihypertensive activity. 

Aldosterone, essentially a corticosteroid in which the methyl group at Cjg is oxidized to a carboxaldehyde, was the last endogenous steroid to be isolated in a form suitable for structural studies. This hormone controls via its action on the kidney both body electrolyte balance and blood volume. A number of modified androstanes, all of which feamre a spirobutyrolactone at C17, act as aldosterone antagonists Those 17-spirobutyrolactones consequently show diuretic and... 

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