An international view of hydroxyethyl starches

Area of Science:

• Pharmacology
• Biochemistry
• Critical Care Medicine

Background:

• Hydroxyethyl starch (HES) is a widely used plasma volume expander.
• Various HES formulations exist globally, differing significantly in pharmacological characteristics.
• Classification by in vitro molecular weight (MW) alone is insufficient due to in vivo metabolic changes.

Purpose of the Study:

• To elucidate the pharmacological properties of different Hydroxyethyl Starch (HES) preparations.
• To highlight the importance of in vivo molecular weight and degradation rates.
• To inform healthcare professionals about HES advantages and disadvantages for optimal patient care.

Main Methods:

• Analysis of HES classification based on in vitro molecular weight (MW).
• Evaluation of factors influencing HES metabolism: degree of hydroxyethyl substitution and C2/C6 ratio.
• Correlation of in vivo MW and degradation rates with therapeutic and adverse effects.

Main Results:

• In vivo MW, determined by substitution and C2/C6 ratio, dictates HES effects.
• Slowly degradable, high MW HES (e.g., 450/0.7) leads to prolonged volume expansion but risks bleeding complications and rheological issues at high volumes.
• Rapidly degradable HES (e.g., 200/0.5, 70/0.5) offers faster elimination and fewer adverse effects on coagulation and rheology.

Conclusions:

• In vivo HES properties, not just in vitro MW, determine clinical outcomes.
• Different HES formulations (e.g., US vs. Europe) have distinct risk-benefit profiles.
• Awareness of HES pharmacological variability is essential amidst evolving market competition and new product development.