Reevaluation of ethylene oxide hemolysis and irritation potential

Area of Science:

• Biocompatibility testing
• Medical device materials science
• Toxicology

Background:

• Ethylene oxide (EO) is a common sterilant for medical devices.
• Assessing EO residue biocompatibility is crucial for patient safety.
• Standardized in vitro and in vivo tests are used to evaluate medical device materials.

Purpose of the Study:

• To investigate the in vitro hemolytic potential of ethylene oxide (EO).
• To assess the in vivo mucosal irritation potential of EO.
• To determine safe EO residue limits for medical devices based on biocompatibility.

Main Methods:

• Prepared serial dilutions of EO in saline (25–10,000 µg/mL) to simulate medical device extracts.
• Conducted in vitro hemolysis assays using red blood cells exposed to EO solutions.
• Performed in vivo mucosal irritation tests on hamster cheek pouches using EO-soaked cotton pellets.

Main Results:

• EO concentrations up to 500 µg/mL did not cause significant hemolysis (<5% after 4h).
• Hemolysis was significant at EO concentrations ≥1250 µg/mL.
• No significant irritation was observed in hamster cheek pouches at EO concentrations up to 2500 µg/mL.
• Significant histomorphological alterations occurred at EO concentrations ≥5000 µg/mL.

Conclusions:

• EO solutions up to 500 µg/mL are not hemolytic.
• EO concentrations up to 2500 µg/mL do not cause significant mucosal irritation.
• Medical devices with EO residue up to 2500 µg/g can be considered safe regarding hemolysis and irritation.