The heterocyclic sulfonamide, 5-acetylamido-1,3,4-thiadiazole-2-sulfonamide, which inhibits the action of carbonic anhydrase in the kidney, causing an increase in the urinary excretion of sodium, potassium, and bicarbonate, reduced excretion of ammonium, a rise in the pH of the urine, and a fall in the pH of the blood; used in respiratory acidosis for diuresis and control of fluid retention, in glaucoma to reduce intraocular pressure, and in epilepsy. Acetazolamide sodium has the same actions and uses as acetazolamide, but is more soluble and suitable for parenteral administration.