The application of radiation to drug products is long overdue and it is refreshing to see it proposed in Chapter 1229.10. Radiation has been used for decades to sterilize medical devices and its benefits include simplicity, reliability and particularly the elimination of sterility testing. The sterility test is known as one of the least reliable, and statistically inaccurate, test methods and any method that could replace it is a major improvement. Since radiation relies on bioburden enumeration, resistance and an established dose, it does not require testing products for sterility.
Despite these benefits there is a major detriment to radiation that was not included in the chapter, that is free radical generation. It has been established that gamma radiation generates free radicals (1)which may deleteriously affect the product, container or container closure. Many years ago free radical generation obviated the use of gamma irradiation to sterilize drug products and it is curious that this chapter did not emphasize the importance of determining the effects of free radicals on sterilized drug products, containers and closures.
The draft of proposed chapter 1229.10 Radiation Sterilization is available for comment (free) at http://www.usppf.com/. After signing in to the Pharmacopeial Forum website, follow the links to issue 39,number 2 (March/April) and it will be in the “General Chapters” section. It is worth checking it out, as there is also a draft of 104 4 Cryopreservation of Cells [NEW] (USP37-NF32 1S) and 1229.4 Sterilizing Filtration of Liquids [NEW] (USP37-NF32 1S) available for comment. USP relies on input from the field, and this is our best chance to make sure upcoming chapters are well-written.
A great review article on the application of gamma radiation for single-use disposables was recently published by Sandle and Saghee (2) and is recommended to the interested reader.
(1) Akkus O, Belaney RM, Das P. 2005. Free radical scavenging alleviates the biomechanical impairment of gamma radiation sterilized bone tissue. J Orthop Res. 2005 Jul;23(4):838-45. http://www.ncbi.nlm.nih.gov/pubmed/16022998
(2) Sandle, T and MR Saghee. 2012. Application of Sterilization by Gamma Radiation for Single-Use Disposable Technologies in the Biopharmaceutical Sector. Pharmaceutical Technology 36(5):s20-s30. http://www.pharmtech.com/pharmtech/article/articleDetail.jsp?id=771889