Plasma extender, 0- -starch

Polysaccharides such as starch and vegetable gums have important pharmaceutical uses as excipients, binding agents for tablets, emulsifying agents and demulcents. Dextran finds employment as a plasma extender to maintain the osmotic pressure of blood. 

Hydroxyethylation of starch, which is obtained from starch and ethylene oxide. This compound has been utilized in papermaking for sizing and coating, in textile manufacturing, and as a blood plasma extender. Hydroxypropylated starch has also practical applications. 

Nonfood hydroxyethyl starch applications are in the paper industry for surface sizing and coating, as quality enhancer for pigmented papers, as wet-end additives in textiles for warp sizing as an adhesive component for bag pastes, case sealing and enveloping materials. Hydroxypropyl starches with higher DS are used routinely in pharmacy as a blood plasma extender. 

The etherified starches are used in solution as plasma substitutes. They are good alternatives to albumin, because they have an extended shelf-life, carry no risk of transmitting blood-borne diseases, and can be infused into patients who refuse blood products on religious grounds. 

Hydroxyethylstarch (HES) is prepared from the amylopectin of waxy maize starch by hydrolysis and subsequent treatment with ethylene oxide. Amylopectin is a branched polyglucose composed of chains of a 1-4 linked glucose residues, to which a number of branches are attached by a 1-6 linkages (Aspinall 1970). When soluble amylopectin is intravenously injected into animals, it is rapidly degraded by a-amylase and is therefore unsuitable as a plasma substitute. For this reason Wiedersheim (1957) suggested substitution of amylopectin with hydroxyethyl groups to slow down the action of amylase and so extend its persistence in the circulation. He showed that such HES preparations had useful properties as plasma expanders and were relatively nontoxic. These results were subsequently confirmed and extended (Thompson et al. 1962, 1964, 1970). 

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