Hydroxyethyl starch in balanced electrolyte solution (Hextend®)-pharmacokinetic and pharmacodynamic profiles in healthy volunteers

Hextend® is a new plasma volume expander containing 6% hydroxyethyl starch (HES) in a physiologically balanced medium of electrolytes, glucose, and lactate (weight average, molecular weight 670 kDa, molar substitution 0.75). This open-label study was designed to investigate the pharmacokinetic and pharmacodynamic profiles of Hextend® in 21 healthy volunteers. We infused Hextend® 10 ml/kg IV over 20 min and determined serum concentrations of HES at selected intervals over a 7-day period. Serum concentration-time curves indicated mixed pharmacokinetic behavior reflecting a two-compartment model in most subjects. The median serum half-life over 7 days was 38.2 h. The balanced formulation of the suspension medium did not seem to affect distribution, metabolism, or excretion of Hextend® when compared with similar HES. Pharmacodynamic analysis demonstrated decreases in some plasma components compatible with the infusion of that volume of fluid and the duration of plasma volume expansion. Other plasma components remained unchanged, reflecting the benefit of a balanced electrolyte solution. Hemodilution was observed for 24-48 h after short-term infusion of Hextend®. Some hemostatic indices showed moderate changes, and serum amylase demonstrated a temporary increase. Our study suggested that Hextend® has pharmacokinetic and pharmacodynamic profiles that are similar to those of other HES.