ABSTRACT
The organic mercurials dominated the field of diuretics for many years but were far from ideal since they required parenteral administration, caused metabolic acidosis that limited their activity, and were associated with renal, hepatic, and cutaneous toxicity. A whole new spectrum of diuretics emerged following the introduction in 1953 of the antibacterial agent sulfanilamide. Osmotic diuretics are substances that are freely filterable by the glomerulus but not reabsorbed. After conservative attempts to manage patients with excessive salt and water, a potassium-sparing agent should be employed in preference to a standard diuretic. Ethacrynic acid is used less than furosemide because of an occasional instance of irreversible hearing loss, and a narrow dose-response curve. Other compounds that are under clinical investigation are bumetanide, azosemide, piretanide, and indepamide. Administration of metolazone also has a distal tubular effect but lacks the strong kaliuresis seen with thiazide diuretics and chlorthalidone. Hypercalcinuria and lowering of serum calcium is an effect opposite to that of the thiazides.
