[Intravascular persistence, tissue storage and excretion of hydroxyethyl starch (HAS)]

Hydroxyethyl starch is a derivative of amylopectin, the branched glycogen-like alpha-1,4-glucose polymer, the amylase hydrolysis of which is retarded by hydroxyethylation. If 70 to 90 per cent of the glucose polymer units contain hydroxyethyl groups, the intravascular persistence and urinary excretion of hydroxyethyl starch of a molecular weight of 435,000 is similar to that of Dextran 70. Hydroxyethyl starch and Dextran 70 are stored briefly in reticuloendothelial and hepatic cells, and cause swelling and vacuolation of renal tubules with little alteration of renal function. Elimination of hydroxyethyl starch from sites of tissue storage is much faster than elimination of the non-metabolized polymers acacia and polyvinylpyrrolidone. The distribution and excretion kinetics of hydroxyethyl starch are thus appropriate for a plasma substitute.