Determining the sterilization tolerance of materials requires simulating actual sterilization cycles and systematically evaluating changes in their physical, chemical, and biological properties. The core objective is to verify that the material maintains its functional integrity and safety after undergoing a specified number of sterilization cycles.
1. Define the Sterilization Method and Usage Scenarios
Disposable devices: Typically undergo 1–3 rounds of sterilization (e.g., factory gamma sterilization + terminal steam);
Reusable devices: Require simulation of 5–10 or more rounds of alternating sterilization (e.g., EO ↔ steam) to reflect repeated clinical handling processes;
High-Reliability Implants: It is recommended to test ≥10 rounds, and combine this with accelerated aging models to predict long-term stability.
2. Design a Reasonable Sterilization Cycle Protocol
|
Key Elements |
Recommended Practices |
|
Sequence |
Set according to the actual clinical usage sequence, such as G → EO → S (Gamma → Ethylene Oxide → Steam) |
|
Dosage/Parameters |
Gamma: 25–50 kGy; EO: 450–600 mg/L, 37–55°C; Steam: 121°C, 15 psi, 30 min |
|
Interval |
72 hours per cycle (recommended for Wuhan area), ensuring complete material recovery and EO desorption. |
|
Pretreatment |
Add 24 hours of 75%RH pretreatment to simulate local storage moisture absorption conditions. |
|
Example |
A Wuhan company successfully passed NMPA registration for its infusion connectors using a 3-cycle G→EO→S process. |
3. Multi-dimensional Performance Testing
The following key indicators must be tested after each sterilization round:
|
Test Item |
Acceptance Standard |
Test Method |
|
Appearance Change |
No discoloration (ΔE < 3), no fogging, no cracks |
Visual inspection + colorimeter |
|
Mechanical Properties |
Tensile/impact strength decrease < 15% |
Universal testing machine (ISO 527/179) |
|
Transparency |
Light transmittance > 85% (visible parts) |
Spectrophotometer |
|
Chemical Safety |
No bisphenol A precipitation, EO residue < 10 ppm |
HPLC, GC-MS |
|
Biocompatibility |
Meets ISO 10993 requirements |
Cytotoxicity, sensitization testing |
4. Data Analysis and Judgment
Trend Analysis: Plot performance degradation curves for each round and identify abrupt change points (e.g., a sudden drop in impact strength > 15% triggers an alert);
Compliance Judgment:
All indicators meet the standards;
No irreversible performance degradation;
Chemical residues do not exceed the standard.
Report output: Includes raw data, equipment calibration records, and an audit trail, complying with GMP requirements.
Recommended practice: Combine with an accelerated aging model (Arrhenius) to predict performance trends over 10 cycles or more to improve evaluation efficiency.
