New Sterilization Technologies

| Home | | Pharmaceutical Microbiology | | Pharmaceutical Microbiology |

Chapter: Pharmaceutical Microbiology : Sterilization Procedures And Sterility Assurance

Heat is the means of terminal sterilization that is preferred by the regulatory authorities because of its relative simplicity and the high sterility assurance that it affords. However, a significant number of traditional pharmaceutical products and many recently developed biotechnology products are damaged by heat, as are many polymer-based medical devices and surgical implants.


NEW STERILIZATION TECHNOLOGIES     

 

Heat is the means of terminal sterilization that is preferred by the regulatory authorities because of its relative simplicity and the high sterility assurance that it affords. However, a significant number of traditional pharmaceutical products and many recently developed biotechnology products are damaged by heat, as are many polymer-based medical devices and surgical implants; for such products alternative sterilization processes must be adopted. Whilst radiation is a viable option for many dry materials, radiation-induced damage is common in aqueous drug solutions, and gaseous methods are also inappropriate for liquids. Aseptic manufacture from individually sterilized ingredients is a suitable solution to the problem of making sterile thermolabile products, but it affords a lower degree of sterility assurance than steam sterilization and is both time-consuming and expensive. For these reasons alternative sterilization strategies have been developed in recent years. Two processes that have progressed to the stage of commercial exploitation are those employing high-intensity light and low-temperature plasma. It must be stressed, however, that although the need to develop alternative strategies for the terminal sterilization of proteinor nucleic acid-containing biotechnology products is one of the stimuli for the investigation of new methods in general, these particular processes are unsuitable for such products.

 
a)   High-Intensity Light

 

UV light has long been known to have the potential to kill all types of microorganisms, but its penetrating power is so poor that it has found practical application only in the decontamination of air (e.g. in laminar-flow workstations and operating theatres), shallow layers of water and surfaces. UV light does not penetrate metal at all, nor glass to any useful degree, but it will penetrate those polymers that do not contain unsaturated bonds or aromatic groups (e.g. polyethylene and polypropylene, but not polystyrene, polycarbonate or polyvinyl chloride). High-intensity light sterilization is based on the generation of short flashes of broad-wavelength light from a xenon lamp that has an intensity almost 100 000 times that of the sun; approximately 25% of the flash is UV light. The procedure has been applied to the sterilization of water and studied as a means of terminal sterilization for injectables in UV-transmitting plastic ampoules in a blow–fill–seal operation. Although pulsed light is unlikely to be useful for coloured solutions or those that contain solutes with a high UV absorbance, it is likely that the procedure will be readily applicable not only to water but to some simple solutions of organic molecules, e.g. dextrose-saline injection.

 

b)  Low- Temperature Plasma

 

Plasma is a gas or vapour that has been subjected to an electrical or magnetic field which causes a substantial proportion of the molecules to become ionized. It is thus composed of a cloud of neutral species, ions and electrons in which the numbers of positive and negatively charged particles are equal. Plasmas may be generated from many substances but those from chlorine, glutaraldehyde and hydrogen peroxide have been shown to possess the greatest antimicrobial activity.

 

Low-temperature plasma is a method of sterilization that is applicable to most of the items and materials for which ethylene oxide is used, i.e. principally medical devices rather than drugs; it cannot be used to sterilize liquids, powders and certain fabrics. Commercial plasma sterilizers, which have been available since the early 1990s, typically consist of a sterilization chamber of about 75 L; this is evacuated, then filled with hydrogen peroxide vapour which is subsequently converted to a plasma by application of an electric field. An alternative commercial plasma sterilizer utilizes alternating cycles of peracetic acid vapour and a plasma containing oxygen, hydrogen and an inert carrier gas. The cycle times are typically from 60 to 90 minutes and the operating temperatures are less than 50 °C. Major benefits of plasma sterilization include elimination of the requirement to remove toxic gases at the end of the cycle (in contrast to ethylene oxide and LTSF processes); there is also no requirement for the treated device to be aired to remove residual gas, and there is no significant corrosion or reduction in sharpness of exposed surgical instruments.

 

Contact Us, Privacy Policy, Terms and Compliant, DMCA Policy and Compliant

TH 2019 - 2022 pharmacy180.com; Developed by Therithal info.