2. Sterilization – DefinitionSterilization – Definition
Sterilization is defined as the process by
which an article, surface, or medium is
free of all living organism either vegetative
or spore form.
17/10/2013 2
3. Commonly used methods of sterilization:
Moist Heat
Dry Heat(i.e use of sterelizing ovens or depyrogenating
tunnels for contineous sterelization)
Gaseous (Ethylene oxide)
Radiation (Gamma or Electron)
Filtration
Others - UV, Steam and formaldehyde, hydrogen
peroxide
Note: All sterilizing equipments should be validated
before use
3
4. Moist Heat SterilizationMoist Heat Sterilization
(Saturated Steam)(Saturated Steam)
Common cycles:
121°C for 15 minutes
134°C for 3 minutes is required but 121°C for 30
minutes is used in practice
The special precaution taken – air must be displaced
from the chamber & from the materials within the
chamber before the cycle begins
Terminal sterilization of aqueous injections,
ophthalmic preparations, irrigation & haemo dialysis
solutions, equipment used in aseptic processing
4
5. Moist Heat SterilizationMoist Heat Sterilization
Not suitable for non-aqueous/dry preparation.
Preferred method of sterilization.
5
6. Dry Heat sterilizationDry Heat sterilization
Lethality due to oxidative processes
Higher temperatures and longer exposure times required
Typical cycles:
◦ 160°C for 120 minutes
◦ 170°C for 60 minutes
◦ 180°C for 30 minutes
◦ Tunnels used for the sterilization of glass vials may use
much higher temperatures (300°) for a much shorter
period
6
7. Dry Heat sterilizationDry Heat sterilization
Used for
Glassware and product containers used in aseptic
manufacture, non aqueous thermostable powders
and liquids
Used for depyrogenation of glassware (≥250°C)
7
8. Gaseous sterilization: Ethylene OxideGaseous sterilization: Ethylene Oxide
Either pure or in mixtures with other inert gases
Requires presence of moisture
Complex process because direct contact between microbial cell &gas
must be eshtablished.
Each sterilization cycle monitored with suitable biological indicators
which are appropriatly distributed
◦ 1-24 hours
◦ 25-1200 mg/L gas
◦ 25-65°C
◦ 30-85% relative humidity
8
9. Ethylene OxideEthylene Oxide
Used for
◦ Heat labile product containers
◦ Surface sterilization of powders
Adequate aeration to reduce toxic residues
9
10. Radiation sterilizationRadiation sterilization
During sterilization radiation dose should be measured
Gamma rays generated by Cobalt 60 ( dosimetry indicators)
Accelerated electrons from an electron generator
25 kilograys (kGy) usual dose
Resistance of organisms not predictable
10
11. Process must be properly validated
Used for:
◦ Dry pharmaceutical products
◦ Heat sensitive materials & product containers
Total radiation dose should be admin. Within pre-
determined time span
11
12. FiltrationFiltration
Removes organisms from liquids and gases sterilized by
sterile filter
0.2 - 0.22 micron for sterilization
Composed of cellulose esters or other polymeric materials
Filter material must be compatible with liquid being filtered
Sterilizing filters considered as starting material &
subjected to quality control test before being used
12