VHP Sterilisation

Hydrogen peroxide vapour is obtained in a generator from a 35% aqueous solution. Such vapour is already very effective at killing spores at the very low concentration of approximately 1500 ppm in the air. 

The sterilisation process takes place at ambient temperature. 

To attain good distribution of the gas, the freeze-drying system is evacuated to a rough vacuum with its own vacuum pump system. After sterilisation, the H2O2 saturated steam is decomposed into water and oxygen with the help of a catalyser. There are no other by-products. For this reason, this process can be considered as completely harmless to the environment. 

After sterilisation and before the freeze-dryer can be opened again, it is important to make sure that the HjOj rest gas concentration has fallen to values 1 ppm. 

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Steiner, R. VHP -Sterilisation of freeze-dryers. ISPE-Seminar Lyophilisation, Antwerp, Nov. 1994. Internnational Society of Pharmaceutical Engineering (ISPE). 

For this, several evacuation and venting cycles must be carried out. The entire sterilisation process is validated as required by the OSHA-Regulations. A VHP sterilisation process is shown in Figure 14.17. 

An alternative to steam sterilisation is the chemical cold sterilisation of surfaces with vaporised hydrogen peroxide (VHP) (Figure 14.16). Hydrogen peroxide vapour is used here as the sterilisation agent. 

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