The plasma volume expansion produced by HEXTEND approximates that produced by 6% Hetastarch in 0.9% Sodium Chloride Injection and the plasma volume expansion of 6% Hetastarch in 0.9% Sodium Chloride Injection in turn approximates that of 5% Albumin (Human).1-4 In randomized, double-blind studies of HEXTEND versus control (6% Hetastarch in 0.9% Sodium Chloride Injection) for the treatment of hypovolemia in elective surgery, 60 patients were infused with a mean of 1596 mL of HEXTEND and 59 patients were infused with a mean of 1428 mL of 6% Hetastarch in 0.9% Sodium Chloride Injection without any serious related adverse events. 59% of the HEXTEND patients and 59% of the control patients required packed red blood cells and other blood-derived products either intraoperatively or postoperatively.
Intravenous infusion of 6% Hetastarch in 0.9% Sodium Chloride Injection results in expansion of plasma volume that decreases over the succeeding 24 to 36 hours. The degree of plasma volume expansion and improvement in hemodynamic state depend upon the patient's intravascular status. When administered intravenously, HEXTEND provides sources of water and electrolytes. Its electrolyte content resembles that of the principal ionic constituents of normal plasma.
Hetastarch molecules below 50,000 molecular weight are rapidly eliminated by renal excretion. A single dose of approximately 500 mL of 6% Hetastarch in 0.9% Sodium Chloride Injection (approximately 30 g) results in elimination in the urine of approximately 33% of the dose within 24 hours. This is a variable process but generally results in an intravascular hetastarch concentration of less than 10% of the total dose injected by two weeks. A study of the biliary excretion of hetastarch in 10 healthy males accounted for less than 1% of the dose over a 14 day period. The hydroxyethyl group is not cleaved by the body but remains intact and attached to glucose units when excreted. Significant quantities of glucose are not produced as hydroxyethylation prevents complete metabolism of the smaller polymers.