Pharmacokinetics of hydroxyethyl starch in normal subjects

To determine the elimination of high-molecular-weight hydroxyethyl starch (HES, Mw 450,000) in normal subjects, ten volunteers were given 500 ml 6% HES solution by intravenous infusion, and serial blood and urine samples were collected for nonglucose total carbohydrate determination. On the average, 46 and 64 per cent of the dose was excreted in the urine within two and eight days, respectively. The plasma concentration declined rapidly during the first week after infusion. The average terminal half-life was 17 days during the first 42 days, which accounted for elimination of about 90 per cent of the dose. The remainder was eliminated with a terminal half-life of 48 days determined between days 42 and 83 of the study. As expected, the infusion of HES resulted in plasma volume expansion over a 48-hour period during which time levels of nonglucose carbohydrates were above 3.5 mg/ml. HES is metabolized by alpha-amylase in the body. During the first 48 hours after infusion of HES, plasma alpha-amylase activity was significantly increased over control. Concomitantly, alpha-amylase activity in urine was also elevated but not significantly so.