STERILIZATION

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Sterilization – Definition Sterilization – 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

Commonly used methods of sterilization:Moist HeatDry Heat(i.e use of sterelizing ovens or depyrogenating

tunnels for contineous sterelization)Gaseous (Ethylene oxide)Radiation (Gamma or Electron)FiltrationOthers - UV, Steam and formaldehyde, hydrogen

peroxide

Note: All sterilizing equipments should be validated before use

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Moist Heat Sterilization Moist 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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Moist Heat SterilizationMoist Heat Sterilization

Not suitable for non-aqueous/dry preparation.

Preferred method of sterilization.

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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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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

Gaseous sterilization: Ethylene Gaseous sterilization: Ethylene Oxide 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 humidity8

Ethylene OxideEthylene Oxide

Used for

◦Heat labile product containers

◦Surface sterilization of powders

Adequate aeration to reduce toxic residues

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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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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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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

Thank You!Thank You!

04/11/23 13