VALIDATION OF VAPOR PHASE HYDROGEN PEROXIDE STERILIZATION PROCESS

Vapor phase hydrogen peroxide (VPHP) is a relatively new sterilization gaseous
agent that is rapidly becoming the gaseous sterilant of choice for many applications,
the most well known being the sterilization of barrier isolation systems.
Its advantages over other gases, such as ethylene oxide, peracetic acid, chlorine
dioxide, and glutaraldehyde, include the following:
1. It does not require temperatures above ambient.
2. There is little or no concern about residual by-products.
Vapor phase hydrogen peroxide equipment and process are described elsewhere
[36]. The basic steps in the process are dehumidification, conditioning,
sterilization, and aeration. More specifically, there are five steps that must be part
of the validation protocol [36].
1. Cycle development
2. Temperature distribution
3. Vapor distribution
4. Biological challenge
5. Aeration verification
Cycle development parameters include temperature, airflow rate, humidity, liquid
peroxide concentration, liquid peroxide delivery rate, peroxide vapor delivery
temperature, and peroxide vapor half-life. Temperature distribution qualification
involves the use of temperature sensors located throughout the sterilant
delivery line and throughout the enclosure. Vapor distribution qualification uses chemical indicators to measure VPHP exposure levels. Biological challenges
involve placement of biological indicators, normally Bacillus stearothermophilus
spore strips or stainless steel coupons at many different locations inside the
enclosure, particularly in those areas most difficult for vapor to contact and
sterilize. Aeration verification determines the parameters (e.g., time, air exchange
rates) necessary to reduce VPHP levels within the system to a certain
value, usually ≤5 ppm. Vapor phase hydrogen peroxide sterilization cycles are
ultimately validated in the same way as traditional aseptic validation processes
via the use of sterile media fills.