Acetazolamide. This drug works in the kidneys by inhibiting an enzyme called carbonic anhydrase. Carbonic anhydrase is the enzyme responsible for moving bicarbonate (sodium bicarbonate) (a base) from the kidney back into the blood stream. Acetazolamide blocks this action, resulting in more acidic blood/more basic urine. This drug has a half-life of 15 hours, so depending on the dose may take a few days to clear.