Prefilled syringes are ready-to-use devices that contain a precise dose of medication. They offer safety, accuracy, and convenience for healthcare providers and patients. Sterilization is a crucial step in their production. It ensures that each prefilled syringe is free of microbes and safe for injection.
Ethylene Oxide (EtO) gas sterilization is the leading method for empty prefilled syringes. This post explores how EtO works, why it matters, and what makes it ideal for prefilled syringe packaging.
What Is Ethylene Oxide (EtO) Sterilization?
Ethylene Oxide sterilization uses a colorless, flammable gas to destroy all forms of microbial life. It works by penetrating packaging and syringes. Once inside, EtO alkylates microbial DNA and RNA. This stops replication and kills bacteria, fungi, and viruses.
Key Features of EtO Sterilization:
Low temperature: Operates between 30 °C and 60 °C.
Deep penetration: Gas reaches hidden surfaces.
Material compatibility: Safe for many plastics and rubbers.
Validated cycles: Consistent and repeatable results.
Why Choose EtO for Prefilled Syringes?
Protects Sensitive Materials
Prefilled syringe components often include plastics like High-polystyrene (Nest box. High-heat methods can warp or degrade these materials. EtO works at low temperatures. It preserves material clarity and strength.
Ensures Package Integrity
Prefilled syringes arrive sealed in protective pouches. EtO gas penetrates these pouches without opening or damaging them. Sterilization happens inside the final package. This sterilization reduces contamination risk during filling.
Broad-Spectrum Efficacy
EtO kills spores, bacteria, fungi, and viruses. It offers a high sterility assurance level (SAL) of 10⁶. This means there is less than a one-in-a-million chance of a viable microbe surviving the cycle.
Regulatory Acceptance
Global health agencies, including the FDA and EMA, recognize EtO sterilization. ISO 11135 sets international standards for EtO processes. Companies validate their cycles to meet these guidelines.
How the EtO Sterilization Process Works
The EtO sterilization cycle has four main phases. Each phase is carefully controlled for safety and effectiveness.
- Preconditioning
- Purpose: Equilibrate load temperature and humidity.
- Process: Packages enter a chamber set to 30 °C–40 °C. Humidity rises to 40–80%.
- Why it matters: Moisture improves EtO penetration.
- Gas Exposure
- Purpose: Kill microbes on all surfaces.
- Process: Introduce EtO gas at 450–1200 mg/L.
- Duration: 2–6 hours, depending on load size and material.
- Aeration
- Purpose: Remove residual EtO and byproducts.
- Process: Transfer syringes to an aeration room or chamber.
- Conditions: 30 °C–60 °C for 12–48 hours.
- Goal: Reduce EtO and ethylene chlorohydrin levels to safe limits.
- Quality Testing
- Bioburden Verification: Confirm initial microbial load.
- Biological Indicators: Verify cycle kill efficacy.
- Chemical Indicators: Ensure proper gas exposure.
- Residual Testing: Measure EtO and byproduct levels on syringes.
Why Sterilization Matters
- Patient safety: Any contamination can lead to infection.
- Product integrity: Microbes can degrade sensitive biologics.
- Regulatory compliance: Standards require validated sterilization processes.
- Shelf life: Proper sterilization extends product stability.
Manufacturers follow strict safety rules to make sure syringes are clean and safe for use. As more people use prefilled syringes, EtO sterilization will keep improving to make drug packaging safer, more efficient, and better for the environment.
