Department of Science and Engineering, Chuo University, Tokyo, Japan
Received date: February 24, 2015; Accepted date: February 26, 2015; Published date: March 05, 2015
Citation: Shintani H (2015) Validation Study of Nitrogen Gas Plasma Exposure Based on ISO Documents (Mainly ISO TC 198 and 194 Documents). Pharmaceut Reg Affairs 4:e150. doi:10.4172/2167-7689.1000e150
Copyright: © 2015 Shintani H. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Visit for more related articles at Pharmaceutical Regulatory Affairs: Open Access
There are so many ISO documents to understand and utilize for validation study and routine control. Biological indicator (BI) is the essential items to conduct sterilization validation and routine control. ISO 11138-1 and ISO 14161 are the major ISO documents to read for both BI manufacturer and BI user, respectively. In ISO 11138-1, BI manufacturer must utilize BI with 106 CFU (colony forming unit)/ carrier as an initial population in validation study. In routine control, it is approved to use 105 CFU/carrier BI in ISO 11138-1.
In ISO 14161 BI user need not imitate BI manufacturer and less than 106 CFU/carrier BI is approved to use for validation study and routine control. According to ISO 14161 for BI user, initial population using validation study and routine control must be identical. To the BI user, there are 4 sorts of sterilization validation procedure and routine control. They are half-cycle methods, over-kill methods, combined BI/ bioburden method and absolute bioburden method (ISO 14161 Annex, Normative). BI with an initial population of 106 CFU/carrier must be used at validation study for BI manufacturer in ISO 11138-1, but BI user can select to use commercial available BI of more than 103 CFU/carrier as BI with an initial population for validation study and routine control in ISO 14161. Approved SAL (sterility assurance level) was defined to be 10-6 and this is unchanged for both BI user and BI manufacturer. In that means, from initial population to SAL of 10-6, survivor curve must be straight and tailing curve should not be observed (Figures 1 and 2). Gas plasma BI, Geobacillus stearothermophilus ATCC 7953 is not the spore causing tailing and present straight survival curve from initial population of 106 CFU/carrier to SAL 10-6, therefore inactivation kinetics is the first order and D (decimal reduction) value can be calculated from the dose or min to decrease 1 log. Chemical indicator (CI) is not approved to use in validation study and only BI is approved to use for evaluation of sterilization validation study. CI is not approved to use in validation study and only approved to use as a support in routine control in ISO 11140-1 and 14161.
I am a Japan delegate of ISO TC 198 and 194. TC means Technical committee. TC 198 covers sterilization of healthcare products. TC 194 covers biological and clinical evaluations of medical devices. As I have been discussed and published ISO relative books and papers, so based on these experience and knowledge, this editorial is prepared. In the current status there is no ISO document covering gas plasma sterilization.
Gas plasma sterilization is useful sterilization procedure to easily attain sterility assurance level (SAL) of 10-6 and material/functional compatibility simultaneously. This is because gas plasma penetration depth is quite shallow (10-20 nm), so material does not deteriorate so easily contrary to the existing sterilization procedures . Current sterilization validation requires SAL of 10-6 and material/functional compatibility simultaneously. If this requirement strictly addresses to the existing sterilization procedures, no sterilization procedures are available, so this requirement of simultaneous attainment of SAL of 10-6 and material/functional compatibility is tentatively neglected. For example, our experiment comparing material compatibility among gamma-ray, autoclaving and ethylene oxide gas sterilization was also significant deterioration of the material of polyurethane  and if this result addresses to the real requirement of sterilization validation, no sterilization procedure was available right now, therefore sterilization validation is the results of compromise.
Therefore, if gas plasma sterilization can be realized, the existing sterilization procedures must be strictly addressed to obtain both SAL of 10-6 and material/functional compatibility. In that meaning inspection is more strict and sterilization validation will be more tough because gas plasma sterilization has a benefit to obtain both in success.
Make the best use of Scientific Research and information from our 700 + peer reviewed, Open Access Journals