Dextran

الوصف

Dextran is a complex, branched glucan (polysaccharide made of many glucose molecules) composed of chains of varying lengths (from 3 to ***0 kilodaltons). It is used medicinally as an antithrombotic (anti-platelet), to reduce blood viscosity, and as a volume expander in anemia.

The straight chain consists of α*1,6 glycosidic linkages between glucose molecules, while branches begin from α*1,3 linkages. (For information on the numbering of carbon atoms in glucose, see the glucose article.) Dextran is synthesized from sucrose by certain lactic-acid bacteria, the best-known being Leuconostoc mesenteroides and Streptococcus mutans. Dental plaque is rich in dextrans. Dextran is also formed by the lactic acid bacterium Lactobacillus brevis to create the crystals of tibicos, a water kefir fermented beverage which supposedly has some health benefits.

It is used in some eye drops as a lubricant, and in certain intravenous fluids to solubilize other factors, e.g. iron (=iron dextran such as Cosmofer) or as a derivative in Monofer.

Intravenous solutions with dextran function both as volume expanders and means of parenteral nutrition. Such a solution provides an osmotically neutral fluid that once in the body is digested by cells into glucose and free water. It is occasionally used to replace lost blood in emergency situations, when replacement blood is not available, but must be used with caution as it does not provide necessary electrolytes and can cause hyponatremia or other electrolyte disturbances.

It also increases blood sugar levels.