Osmotic diuretic

from Wikipedia, the free encyclopedia

Osmotic diuretics (also: osmodiuretics , osmotics ) are high-molecular substances , i.e. those with a high molecular mass that are freely filtered in the glomerulus of the kidney , but cannot be reabsorbed in the further course of the renal tubule . As a result, they osmotically retain water in the urine , which would normally have been reabsorbed from the primary urine.

Because of their high molecular weight, osmotic diuretics can usually not be absorbed through the intestine and must therefore be administered parenterally .


  • Mannitol (mannitol infusion solution, osmofundin)
  • Sorbitol (sorbitol infusion solution)

Another example of an osmotic diuretic is glucose (grape sugar). In people with diabetes , when the blood sugar level reaches a certain level, glucose crosses over into the urine when the filtration capacity of the kidney tubules is exhausted. This triggers an increased flow of urine, as sugar binds water osmotically. This fact gave the diabetes its name: Diabetes mellitus means in German "honey-sweet flow".

The same applies to increased serum concentrations of urea in a protein-rich diet and to bicarbonate in the case of stays at high altitudes.

Application example

Mannitol is used, for example, to treat brain edema . Here, a hypertonic solution of the active ingredient is infused intravenously so that the excess water can flow off following the osmotic pressure and consequently the intracranial pressure in the affected area drops.

See also

Individual evidence

  1. ^ Osmotic diuretic. DocCheck , accessed on December 11, 2019 .
  2. ^ A. Zeeck, S. Grond, I. Papastavrou, SC Zeeck: Chemie für Mediziner , Munich 2010, p. 68.