What Is Sterilization?
Sterilization is any process that removes, kills, or deactivates all forms of life. Sterilization is related to the term sterile, which means a complete absence of viable microorganisms or microbes that have the potential to reproduce.
What is Sterile Filtration?
Sterilization by filtration (also known as sterile filtration) is a “cold” method of sterilization that removes microbes instead of killing them.
How Is Sterile Filtration Performed?
- The sterile filter then removes particulate matter and microorganisms from the non-sterile liquid formulation.
- Particles are collected on the surface of the filter during sieving and screening.
- Membrane filters are used for sterilizing solutions
- Often filter membranes are composed of cellulose esters, nylon, polysulfone, polycarbonate, PVDF, or polytetrafluoroethylene.
- The filter and housing are steam sterilized before product filtration, typically by steam-in-place (SIP) systems. Pressurization during SIP sterilization must be gradual to maintain filter integrity. Often filters are dried with compressed air after sterilization and before use.
Sterile Filtration FDA Guidance Considerations:
1. Type of particle—Particle source (metal, microbe etc.), shape, charge, and size.
2. Filter material—Filter composition affects the charge-related attraction of particles, including microorganisms.
3. Filter membrane thickness—Filter thickness slows the fluid flow and affects the particle adsorption.
4. Filter porosity—The smaller the porosity, the greater the retention of microorganisms and the slower the flow rate.
5. Type of fluid being filtered—Highly viscous products will require applied pressure to move the product through the filter.
6. Applied pressure, flow rate, and usage time—Pressure, flow rate, or usage time increases can harm filter integrity and affect microbe sizes.
Data for filter-product compatibility qualification include:
1. Limits for flow rates, temperature, and pressure
2. Ensure that the filter meets the non-fiber releasing criteria
3. Procedures for filter sterilization
4. Diffusion rate for the in-process integrity tests
5. Integrity test value and the amount of test organism (diminuta) which can be retained
5. Specifications and instructions for the filter integrity test
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Resource Person: Hassan Hussein
