Sterilisation is essential for the breakdown of all microorganisms, such as spore-forming and non-spore forming bacteria, viruses, fungi, and protozoa, that may create health threats from pharmaceutical and other material contamination.
The most reliable and commonly used classical sterilisation techniques are those that use either hot air or saturated steam under pressure. Additional methods for sterilisation include filtration, ionizing radiation (gamma and electron-beam radiation), and gas (ethylene oxide, formaldehyde).
Subjecting microorganisms to saturated steam under pressure in an autoclave ultimately allows for the recording of their breakdown by the irreversible denaturation of enzymes and structural proteins. Therefore, sterilization in saturated steam needs strict control of pressure, temperature and time.
The key lethal process in dry-heat methods is the oxidation of cell constituents. This particular dry-heat method requires a higher temperature than moist heat, as well as a longer exposure time.
Sterilisation of particular active ingredients, drug products and medical devices in their final packaging can be achieved through the exposure to gamma radiation from appropriate radioscopic sources such as 60CO (cobalt 60) or of electrons energized by a suitable electron accelerator.
The active agent of gas sterilization process is ethylene oxide as well as other highly volatile substances. Unless these agents are mixed with suitable inert gasses that will minimise toxic properties as well as possibilities of toxic residues remaining in treated materials, the flammable and potentially explosive nature of agents may be a disadvantage.
