Sterilizer s

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Prepared byMs.K.Neelima I . M.Pharm. ,

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Under the guidance of S.CHELLARAM, M.Pharm .,


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Sterilization is an essential concept in the preparation of sterile pharmaceutical products.

It is a process by which all viable microorganisms areremoved or destroyed, based on a probability function.

Sterilization makes object free from all microbial forms,including bacterial spores.

Sterilization aim to provide a product that is safe andeliminates the possibility of introducing infection.

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Ophthalmics Parenterals Surgicals

Clean room garments 04


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The equipments used for sterilization is termed as

sterilizers.

Sterilizers play an important role in the manufacturing of

ophthalmic and parenterals.

Based on the principle of working, the sterilizers areclassified as

Moist heat sterilizersDry heat sterilizers

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Sterilization is done by using saturated steam under

pressure.Moist heat is more effective than dry heat for

sterilization for thermo labile materials like plastics rubberarticles etc.

Factors influencing the sterilization process areTemperatureTime andSteam penetration.

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According to USP XXI and BP 1988 the standardcycle for steam sterilization are given as 15 lbspressure at 121 C for 15 min.

OPERATING CONDITIONS

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S .No

Temperature(c)

Pressure(psig)

Time(min)

1. 121 15 20 - 30

2. 132 28 5 - 10


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For porous loads (dress materials) sterilizers aregenerally operated at a minimum temperature of 134 C .

For bottled fluid, sterilizers are employed at a minimumtemperature of 121 C .

Mechanism of sterilization in moist heat sterilizers

The saturated steam under pressure causes the

denaturation of proteins in viable organisms which leads todeath of microbes.

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Material of construction Structure Ways of feeding stream into jacket and chamber Management system Process

Removal of air from the chamberHeating sterilizationPost sterilization phases

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FEATURES OF SATURATED STEAM AUTOCLAVE


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These are made of class AISI 316 stainless steel

including valves and piping. The gaskets used are made of silicone rubber or Teflon

and their derivatives.

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These generally have aquadrangular or cylindricalchamber.

Saturated stream autoclaves aregenerally jacketed .


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Two door autoclaves areused to separate the loading areaand unloading area.

Loading area- where products to

be sterilized are placed.

Unloading area- where alreadysterilized products are placed.

There may be two ormore doors.

When the autoclave leadsto a sterile room there are alwaystwo rooms.

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Unloading

area orsterile area

Loadingarea

Sterilizedproducts

Productsto besterilized

do

or

do

or

Jacket

Industrial steam

Pure steam

Chamber

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There are 2 ways Single feed:

In this type, the stream circulates first in the jacket

and passes from the jacket into the chamber.

Separate feed:

In this type, usually the chamber is fed pure streamand the jacket is fed industrial stream.

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Pressure and temperature control is performed with aproportional integral derivative method.

Some management systems offers flexibility in composingprograms and in setting parameters even to operators whohave no knowledge of electronic programming.

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Removal of air from the chamber

Heating & sterilization

Post sterilization phases

The steps involved in the process of saturated steamautoclave were as follows


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Removal of air from the chamber:Reason:

The air that are initially present in the autoclavechamber was to be removed since they areincondensable and entrained by the steam.

As the air inside the chamber is 2 times more denserthan the steam, these tend to settle in the lowerportions of the chamber creating temperature

gradients.

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Methods to remove air:

There are 2 methods availablePulsed vaccum:

In this type, once the initial vaccum has beenreached the pump is stopped and steam is introduced

in the chamber then vacuum is produced again.Dynamic vaccum:

In this type, once the initial vaccum has been

reached, the pump continues to run but at the sametime a 5 to 10 mins injection of stream is performed.

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Heating & sterilization:

During heating phase and much less

sterilization phase considerable amounts of condensate form in the chamber which must beremoved from the chamber.

Two extraction methods areA condensate trap located at the bottom of thechamberDynamic steam

During heating and sterilization process thevaccum pump is kept running and draws thecondensate from the chamber through a low capacityvalve.

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Post sterilization phases:parameters change based on the material to

be sterilized

Intensity of vaccum and duration of vaccumcooling by circulating cold water in the jacket

cooling by spraying water on the loadampule tightness with fast vaccumcooling with air counter pressure

spontaneous coolingampule tightness test with dye solutionpenetration

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Structure Schematic diagram Process

Heating phaseSterilizing phase

Cooling phase Limitations

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FEATURES OF SUPERHEATED WATER SPRAY AUTOCLAVE


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The chamber has a circular cross section and has a single wall.

Inside the chamber sprayers are present at the upper side to spraywater on load.

On right portion: It has electronic process controller, air steam drain, air

sterilizing filter and inlet for treated D.I water for chamberrefilling.

Left portion: It has inlet for cool water, removable heat exchanger plate and

water drain. 23


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Heating phase:

At the beginning of the program after the goods have loaded,the lower circular sector is filled with purified water.

This water is drawn by a sanitary type pump, circulates in aheat exchanger which is indirectly heated with industrial

steam.

The water then returns into the upper part of the chamber andis distributed to the load by a system of solid cone spraynozzles.

The uniform redistribution of water on the lower layers of theload is ensured by appropriate perforated racks that support theload.

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Sterilization phase: The heating of the circulation water and the load is gradual and

quite fast.ex: The temperature 121 C is reached in 20-30 minutes.

It depends on the solution, the material and shape of the

containers.Cooling phase: Cold tap water now flows in the plates of the exchanger where

stream was flowing earlier.

In less than 15 minutes the temperature drops to approximately70 C.

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Even through the moist heat sterilization is most

recommended, however the normal moist heat cycles do notdestroy pyrogens.

It is not suitable for moisture sensitive materials like paper,

plastic, oils & dry powders.

When PVC bags are sterilized, the phenomenon of blushing,whitening of the PVC due to water absorption usually occurs.

The clean room garments got wet which may causeinconvenience for immediate use after steam sterilization.

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Structure Schematic diagram Process

Sterilizing phase

Cooling phase

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FEATURES OF AIR OVER STEAM AUTOCLAVE


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Sterilizing phase: The steam enters into the chamber through a sprayer located in

the chambers lower portion. This causes the sterilization of the load placed in the chamber.Cooling phase:

It consist of feeding air into the chamber which replaces all thesteam present in the chamber.

Then cold tap water is fed into the heat exchangers which islocated in the two circular sectors of the sides of the chamber.

The load is thus cooled while constantly maintain a controlledpressure inside the chamber.

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Many objects are best sterilized in the absence of

water by heat sterilization.

It is an alternative for moisture sensitive materials like oiland dry powders.

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FOR STERILIZATION

S . No Temp.

(in c)

Time

(in min)1. 160 120 - 180

2. 170 90 to 120

3. 180 45 to 60

OPERATING CONDITIONS


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S . No Temp.(in c)

Time(in min)

1. 230 60 to 90

2. 250 30 to 60

FOR DEPYROGENATION

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There are various temperatures and periods of treatment fordry heat depending on th e Pharmacopeia .

US Pharmacopeia states that the dry heat sterilization process forcontainers and sterile pharmaceutical products should be at a temp.of 160-170 c for a period of 2-4 hrs.

British Pharmacopeia states that the dry heat sterilization processfor containers and sterile pharmaceutical products should be not lessthan 160 c for at least 1 hr.


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Some of the types of dry heat sterilizers areDry heat batch sterilizer

Dry heat tunnels

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This type of dry heat unit is most widely used inthe industry.

As the name indicates it is used for batchproduction.

Material of construction

Structure Schematic diagram Process of sterilization

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FEATURES OF DRY HEAT BATCH STERILIZER


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The unit is entirely made of stainless steel.

Particularly care must be taken in selecting the

insulating materials.

All the materials used for the construction of

sterilizer should be heat resistant and shouldprovide the satisfactory service life.

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It consist of Two door sterilizer in which the

unloading door leads to the sterilearea

Air circulation fan

Water cooled battery

Circulation HEPA filters

launch\ recovery bulkheads Trolley and load Discharge duct

HEPA filter on the discharge duct toprevent back flow contamination

Variable speed fan for chamberpressurization

Prefilter and HEPA filter on thechamber pressurization loop

Electric heater 37


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It uses the principle of convective heat transfer to heatthe load to get sterilized.

The pressure inside the chamber must be controlledcontinuously so that it is

higher than the pressure in the loading area (non sterile) and

lower than the pressure in the unloading area (sterile).

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It is the only continuous sterilizing apparatuswidely used in the pharmaceutical industry.

Material of construction

Structure

Schematic diagram

Process

FEATURES OF DRY HEAT TUNNEL


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It consist of horizontally rotating transport belt installedin a thermally insulated tunnel that directly connects anupstream cleaning machine to the downstream sterilearea.

It consist of 3 zones

Pre heated zone: where loading takes place

Heating zone: consist of heaters and temperature

sensors that are covered by insulator Cooling zone: consist of HEPA filter for air supply

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Inside the tunnel the product is dried, heat treated

by either by radiant heat or by hot air and finallycooled.

Infrared radiant heat tunnel:

In this type, heat is supplied by resistance in glassheaters located above and below the transport belt.

Hot air laminar flow tunnels:

In this type, heating is provided by heating barspresent above and below the transport belt.

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In both cases the internal part of the tunnel must bepressurized dynamically by ventilation at anintermediate pressure level between the down streamsystem and the loading room.

Pre filtered and HEPA filtered air is fed into the cooling

zone mainly for cooling.

This air slowly flowing through the entire tunnel, has

also an important drying and preheating effect of theload in the feed zone.

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Property Moist heat Dry heat

Penetrating potency higher lower

Temp for protein clotting lower higher

Extra heat released yes nofrom condensation

Sterilizing potency: Moist heat >> Dry heat45


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Sterilizer s