Sterilization is defined as removing all living organisms from a surface or medium. Common sterilization methods include moist heat, dry heat, gases like ethylene oxide, radiation, and filtration. Moist heat sterilization using saturated steam at 121°C for 15 minutes is preferred and used for aqueous solutions and equipment. Dry heat at higher temperatures like 160°C for 120 minutes is used for non-aqueous items and glassware. Ethylene oxide gas is used below 50°C and 85% humidity for heat-sensitive items. Radiation doses of 25 kGy are used for dry pharmaceuticals. Filtration with 0.2 micron filters removes organisms from liquids and gases. All sterilization

1. STERILIZATION
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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.
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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
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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
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5. Moist Heat SterilizationMoist Heat Sterilization
 Not suitable for non-aqueous/dry preparation.
 Preferred method of sterilization.
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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
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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)
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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
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9. Ethylene OxideEthylene Oxide
Used for
◦ Heat labile product containers
◦ Surface sterilization of powders
Adequate aeration to reduce toxic residues
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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
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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
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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
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13. Thank You!Thank You!
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