Aseptic sterilizing agents

Sterilization can be achieved by moist or dry heat, by ethylene oxide (or other suitable gaseous sterilizing agent), by filtration with subsequent aseptic filling of sterile final containers, or by irradiation with ionizing radiation (but not with ultraviolet radiation unless the process is thoroughly validated). Each method has its particular applications and limitations. Where possible and practicable, heat sterilization is the method of choice. 

Ophthalmic ointments usually contain petrolatum as the base. The petrolatum is sterilized by dry heat and combined with the sterile dmg powder under aseptic conditions. Ophthalmic suspensions contain very fine (- 10 ji) particle sized soHds suspended in an aqueous vehicle. The vehicle is adjusted to isotonicity and viscosity-increasing excipients, chelating agents, and surfactants also may be needed. The aqueous vehicle in these cases is generally autoclaved and mixed with sterile dmg powder asceptically (30). 

Depending upon the intended application, the antibody may next be conjugated to specific molecular tags (e.g. a radionuclide or toxin). Finally, stabilizing agents (e.g. buffer components, glycine or sometimes human serum albumin) are added to the product. This is then aseptically filled into the final containers after sterile filtration. The product is then usually freeze-dried and sealed under an atmosphere of an inert gas. 

Another group of blood tests involves bacteriological techniques. Blood and bone marrow samples are obtained under aseptic precautions and introduced into a variety of artificial culture media, with subsequent isolation and identification of the specific microorganism responsible for the illness. Relative susceptibility of the specific strain of bacteria to the available chemotherapeutic and antibiotic agents may then be determined and the effectiveness of such agents in sterilizing the blood-stream can be determined by further blood cultures. 

In general, extensive use of in-process storage areas should be avoided. It is best to operate the aseptic facility in a just-in-time mode in which components and equipment are sterilized shortly before they are required for use in the filling or compounding areas. Some limited storage is necessary for nonproduct contact materials such as sanitizing agents, environmental supplies and equipment, and other items. 

Ethylene oxide (bp, 10.8°C) is a gaseous alkylating agent. It alkylates proteins and ribonucleic and deoxyribonucleic acid in micro-organisms. It replaces labile hydrogen with hydroxyethyl groups. Ethylene oxide is utilized as a surface sterilant. Bulk crystalline materials can occlude vegetative bacterial cells or spores with crystals. Consequently, ethylene oxide does not reach them. The final step prior to sterilization is an aseptic recrystallization step. 

Sterilization in place—Closed systems such as process vessels, dryers, centrifuges, isolators, and other items should be subjected to a validated sterilization procedure, which assures that all internal surfaces have been rendered free of microorganisms. Sterilization-in-place (SIP) procedures reduce the number of aseptic manipulations necessary to ready the equipment for use in the aseptic production processes and as such are considered preferable to aseptic assembly of systems from individually sterilized components (25). The SIP procedure should allow the system to maintain sterility until ready for use without aseptic manipulations. Sterilization-in-place procedures could employ steam, gas, dry heat, radiation, chemical agents, or other validateable sterilization procedure. 

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