The document outlines aseptic techniques essential for preventing contamination in pharmaceutical preparations and testing. It defines various sterilization processes, including dry heat and moist heat sterilization, alongside their methods, advantages, and disadvantages. Additionally, it details sources of contamination, terms related to sterilization, and the design and operation of sterilization equipment like hot air ovens and autoclaves.

1. Aseptic Techniques
Prepared by
Apu

4. Overview
 To prevent contamination during the preparation and testing of pharmaceutical
products.
 Prevent contamination of the specific microorganism we are working with.
 Prevent contamination of the room and personnel with the microorganism we
are working with.
What is the Aim of Aseptic Technique?
 Aseptic technique refers to a procedure that is performed under sterile
conditions.
 This includes medical and laboratory techniques which deal with cultures and
human cells and tissue for transplantation, etc.
 It is a procedure that does not allow the access of micro-organisms from
possible sources such as ingredients, solvents, mixing equipment , final
containers , working area, the operators hand and other contact parts.

5. Sources of Contamination
 The Atmosphere
 The Breath
 The Hands
 Clothing
 The Hair
 The Working Surface
 Equipment

6. Some Basic Terms
 Sterilization: It is the process by which article, surface or medium is made
free from all microorganisms either in the vegetative or spore state.
 Spore is a reproductive structure that is adapted for dispersal and surviving
for extended periods of time in unfavorable conditions. of the lifecycles of
many bacteria, plants, algae , fungi and some protozoa.
 Sterile/Sterile products: A products is said to be sterile when it is free from
all living microorganisms.
 Disinfection: It is the process by which an article, surface or medium is made
free from all pathogenic microorganisms (that is organisms that are capable
of giving rise to infection).
 Antisepsis : It is the process by which the growth of bacteria is inhibited but
they are not killed (chemicals or disinfectants that can be safely applied on
skin or mucous membrane)
 Decontamination: It is the process of rendering an article or area free of
contaminants, including microbial, chemical, radioactive and other hazards.

7. Other Terms Used in Relation to
Sterilization
 Bactericides : These are the substance used to kill bacteria.
 Bacteriostatic agents : These are the agents which inhibit the growth of
bacteria ( only prevent multiplication of bacteria, but they remain alive)
 Fungicides : These are the agents which kill fungi.
 Germicides: These are the substance which kill germs.
 Mycocides: These are the agents which kill molds.
 Viricides: These are the agents which kill viruses.

8. What need to be sterilized in the
process of aseptic technique?
 Culture media
 Fluids used in the labs
 Reagents
 Laboratory containers
 Laboratory equipment
 Medical and surgical instruments
 Vaccine and biological products
 Parental pharmaceutical products
 Certain foods

9. Methods of Sterilization
Physical
Method
Dry Heat
Hot Air Oven
Flaming
Moist Heat
Radiation

10. Methods of Sterilization
Chemical Method
Gaseous Sterilization
Sterilization by
Disinfectants
Mechanical Method Filtration

11. Sterilization by Dry Heat
 All microorganisms including bacterial spores can be destroyed by heat.
 Sterilization by dry heat is usually carried out in a apparatus known as hot air
oven.
 Heat is transferred from its source to the load by radiation, convention and to
a lesser extent conduction.
 During this process the microorganisms are killed by oxidation.
 It is a function of time temperature combination.
 It is the simplest and most economical method of sterilization.
 It is less effective than moist heat because higher temperature and longer
periods of exposure are required.
 Therefore, The economy must be considered during the time temperature
relationship.

12. Design of Hot Air Oven
 Hot air oven or dry heat sterilizer
consists of a metallic chamber of
aluminium or stainless steel, which
is electrically heated and
thermostatically controlled.
 The chamber of the oven has
double walls which are separated
from each other by thick layer of
glass-fibre insulation.
 The hollow flanged door is also
filled with glass fibre insulation.
 The inner side of the door is fitted
with asbestos gasket that provides
a tight seal to prevent heat loss.

13. Design of Hot Air Oven
 Depending on the size of the oven 3-4
perforated salves are provided in the
chamber which can be removed as and
when desired.
 A good quality of thermometer is fitted in
front of the chamber for noting the
temperature the process.
 A fan is provided for air circulation in the
oven.
 A vent is fitted at the top of the oven .
 A on-off switch is provided along with
green and red indicators.
 The heating elements are fitted on the
lower side of chamber.

14. Method of Use
 Articles are to be arranged in a manner to allow free circulation of air. (For
getting good results the oven should be properly loaded so that all the articles
are exposed to uniform heat for required time.)
 Care should be taken that the oven is not opened in between the sterilization
operation.
 Generally, the oven can be operated fron 50⁰ to 300⁰ C (122 to 572 F)
 Precautions :
- Glass wares should be dry.
- Oven should not be over loaded
- Door of oven should be opened after it cools down (2 hr.)
Applications
 Glassware, eg. Volumetric flask, Pipette, All- glass syringes
 Other instruments, eg. Forceps, Scissors, Scalpels
 Oil and Similar Anhydrous Material, eg. Liquid paraffin
 Powders, eg. Dusting powder

15. Advantages and Disadvantages
 Advantages
1. It is the most suitable method of sterilization for moisture sensitive material. Example : Oily
substance and dry powders
2. It is suitable for assembled equipment providing sufficient time for penetration. Example : All
glass, syringes, test tube etc.
3. It is less damaging to glass and metal equipment than moist heat.
4. The method is economically safe.
 Disadvantages
1. It requires high temperature and long exposure time.
2. Most medicaments ,rubber and plastic articles which are thermolabile get destroyed by this
method.
3. Preparations containing H2O, alcohol, other volatile substances cannot be sterlized,
sterilized by this method because the liquid may evaporate at high temperature.
4. It is unsuitable for surgical dressing because the natural moisture of the fibers quickly
vaporizes which leads to deterioration and ultimately charring may take place.
5. Drastic nature may appear in high temperature, eg. A tube cannot be sterilized after filling
because, if closed it many burst from expansion of contents.

16. Sterilization by Moist Heat
 Moist heat sterilization: Moist heat sterilization is also known as steam
sterilization.
 Microorganism can be exposed to moist heat by using
• Hot water
• Boiling water
• Steam at atmospheric pressure
• Steam under pressure
 Moist heat is believed to destroy microorganisms by causing protein coagulation or
denaturation.
 It can kill microorganisms at lower temperature and in shorter times than dry
heat.
 For example, all vegetable bacteria are destroyed by 1 hour at 80⁰C and very few
will survive 10 minutes at this temperature.
 The spores of pathogens, however require 30 minute at 115⁰C will also destroy
easily the vegetative forms of molds, yeasts and yeast spores.

17. Factors affecting sterilization by moist heat
 pH
 Inhibitory medicaments
 Protective substances
 Initial number of organisms
 Inactivation factor of the process

18. Principle of sterilization by stem under
pressure
 Steam under pressure is allowed to penetrate through the materials.
 Pressure itself has no sterilizing power.
 Steam is under pressure to obtain temperatures high enough to destroy micro-
organisms quickly.
 Greater the pressure applied Higher the temperature obtained
Lesser the time required.
 Steam for Sterilization can be obtained in two ways:
1. Wet Saturated Steam
2. Dry Saturated Steam

19. Principle of sterilization by stem under
pressure
 The apparatus for sterilization by steam under pressure is called an autoclave
or steam sterilizer.
 Autoclaving is the process of heating in an autoclave in which saturated steam
under pressure is allowed to penetrate through the materials for at least 15
minutes at a minimum temperature of 1210C.
 The amount of time begins when the temperature of the material being
sterilized reaches at 1210C.
 Autoclaves mainly are of two types:
1. Portable
2. Large Sterilizes

20. Key Features of Portable Autoclave
 A portable or bench autoclave is quite similar to pressure cooker.
 It is a hollow cylindrical vessel of about 15 liters capacity.
 Made of aluminum or stainless steel, fitted with a lid which can be firmly secured.
 In one type of autoclave the lid is fitted with eight screw clamps, a pressure gauge
an air vent and adjustable safety valve .
 The externally fitted lid has the advantage that whole capacity of the vessel can
be used but at the same time.
 It has disadvantage also that even if one clamp is damaged or left loose, the
pressure imposed on others may lead to explosion.
 Therefore it is essential that all the clamps should be secured and carefully
maintained.
 The autoclave is electrically heated, the electric elements are fitted at the
bottom of the autoclave.
 It is provided with a perforated metallic basket fitted with legs, in which the
material to be sterilized is placed.

21. Operation of Portable Autoclave
 The perforated metallic basket is taken out of
the vessel.
 A bucket full of water is put in the vessel so that
the heating elements get completely immersed
in water.
 The material to be sterilized is loosely packed in
the basket which is then kept in autoclave.
 Care should be taken that the basket should not
touch the water.
 After sometimes the water in autoclave starts
boiling and steam generated in the body of
autoclave.
 When the steam is passed freely through the
autoclave the vent for minute, close the vent.
 As the pressure inside the autoclave increases
the temperature also increases and reaches to
the sterilization point controlled by thermostat
which is generally, 10 pounds per square inch at
1150C for 30 minutes 15 pounds per square inch
at 1210C for 20 minutes.

22. Advantages and Disadvantages
 Advantages
1. The penetrating power of steam is much more than that of dry heat. So
microorganisms are killed more efficiently in lesser time at lower
temperature than dry heat.
2. In large size autoclaves large quantities of materials can be sterilized in one
batch.
3. Solutions packed in sealed containers as ampoules are readily sterilized by
this method.
4. Bulk solutions, glassware, surgical dressings, rubber gloves and surgical
instruments are effectively sterilized by this method.
 Disadvantages
1. This method is unsuitable for materials which cannot withstand the heating at
1150C or more.
2. This method is not useful for oils, fats, ointments, powder , oily injections
and other preparations through which steam cannot penetrate

23. References
 Test Book: COOPER and GUNN’S “Dispensing for Pharmaceutical Students”;
Twelfth Edition; Edited by S J Carter
 Web resources

24. Thank you