Acetazolamide: a forgotten diuretic agent.

Acetazolamide is the only carbonic anhydrase inhibitor with significant diuretic effects. It is readily absorbed and undergoes renal elimination by tubular secretion. Its administration is ordinarily marked by a brisk alkaline diuresis. Although carbonic anhydrase inhibitors are proximal tubular diuretics (where the bulk of sodium re-absorption occurs), their net diuretic effect is modest in that sodium re-absorption in more distal nephron segments offsets proximal sodium losses. Acetazolamide use is limited by both its transient action and the development of metabolic acidosis with extended administration. Acetazolamide can, however, correct the significant metabolic alkalosis which occasionally occurs with loop diuretic therapy.