Sterilization methods used in pharmaceutical industry

1. Presented By:
Owais Ahmed
Manager QA (Validation)
Dated: Sep 07 , 2022

2. What is Sterilization?
 Sterilization describes a process that destroys or eliminates all forms of
microbial life and is carried out by physical or chemical methods.
Methods:
 Moist or dry heat,
 Irradiation with ionizing radiation.
 Ethylene oxide (or other suitable gaseous sterilizing agents)
 Filtration with subsequent aseptic filling of sterile final containers.
Method of Choice:
 Where possible and practicable, heat sterilization is the method of choice.
In any case the sterilization process must be in accordance with the
marketing and manufacturing authorizations

3. MOIST HEAT STERILIZATION
 The process of thermal sterilization employing saturated
steam under pressure is carried out in a chamber called
an autoclave.
 It is probably the most widely employed sterilization
process.
 The basic principle of steam sterilization, as accomplished
in an autoclave, is to expose each item to direct steam
contact at the required temperature and pressure for the
specified time.
Parameters :
 Minimum 121°C for 15 minutes at 15 PSI

5. MOIST HEAT STERILIZATION
 Apart from that description of sterilization cycle
parameters, using a temperature of 121°, the F0 concept
may be appropriate. The F0, at a particular temperature
other than 121°, is the time (in minutes) required to provide
the lethality equivalent to that provided at 121° for a stated
time.
 Lethality (L) is defined as the relative effect of each
temperature in relation to the microbial inactivation of the
temperature of reference.
 F0>15 minutes

6.  z-value is the number of degrees the temperature is
required to be increased which will cause a 10-fold
variation in the D-value.
 D-value is the time (t) required at a specified
temperature (T) to reduce the microbial population
from 100% to 10% (i.e. 90% or 1 log reduction).

7. F0 value is the equivalent exposure time at 121.1°C to that of the actual
exposure time at a variable temperature calculated with a temperature
coefficient of the destruction of 10°C.
F0 Value Definition
F0 Value (Equivalent E
where,
Δt – the time interval between two temperature readings
T – the temperature at time t of the product under sterilization
z – temperature coefficient (assumed as 10°C)

8. Consider sterilization hold time of 30 minutes at constant 110°C instead of 121.1°C, in a
similar manner as above,
Solving we get, F0=2.33 min.
Hence, 30 minutes of sterilization at 110°C is lethally equivalent to 2.33 min. of sterilization at
121.1°C.
EXAMPLE # 1

9. Consider sterilization hold time of 30 minutes at constant 125°C instead of
121.1°C, in a similar manner as above,
Calculate the F0 value.?
Question

10. Answer
Solving we get, F0=73.64 min.
Hence, 30 minutes of sterilization at 125°C is lethally
equivalent to 73.64 min. of sterilization at 121.1°C.

11. Question
 How long will it take to complete the sterilization?”
for this condition. Meaning, if we maintain
temperature 125°C constantly, how much hold time
is required to achieve an F0 value of 30 minutes.

12. SOLUTION
By reverse calculation, we can do this. Let’s fix the F0 value to 30 min. The unknown part then
would be Δt.
Data we have now is F0=30 minutes and Temperature T=125°C
Putting these values in equation (2),

13. ANSWER
 Solving we get, Δt = 12.24 min.

14. QUALIFICATION OF AUTOCLAVE
 The different tests are follows for qualification of
autoclave are
 Vacuum leak test
 Bowie-dick test
 Heat distribution study
 Heat penetration study
 Biological Challenge Test

15. QUALIFICATION TESTS
Vacuum leak test:
Objective:
To verify the leakage in sterilization chamber during vacuum
hold time when the sterilizing chamber is empty.
Bowie- Dick test:
Objective:
To ensure that the vacuum pulses applied before the
sterilization hold period are sufficient to remove the
entrapped air or non-condensable gases so as to facilitate the
event and rapid steam penetration into all parts of load and
maintaining this condition during sterilization holding time.

16. BOWIE DICK TEST

17. QUALIFICATION TESTS
Heat distribution study (loaded chamber)
Objective: To verify the temperature uniformity throughout the
chamber and to locate the cold spot in loaded Chamber. The
sterilizer is capable attaining a temperature of 121°C throughout the
sterilizing hold period in loaded Chamber.
Heat penetration study
Objective In order to verify sterilizing temperature has been
reached in each load subjected to moist heat sterilization, it is
necessary to conduct heat penetration studies. This study is
conducted to ensure that the coolest unit within a pre-defined
loading pattern (including minimum and maximum loads) will
consistently be exposed to sufficient heat lethality (minimum
"F0").

18. BIOLOGICAL CHALLENGE TEST

21. DRY HEAT STERILIZATION
 A hot air oven is a type of dry heat sterilization. Dry heat sterilization is used on equipment
that cannot be wet and on material that will not melt, catch fire, or change form when
exposed to high temperatures
 A dry-heat sterilization/depyrogenation system is supplied with heated, HEPA filtered air,
distributed uniformly throughout the unit and employing a blower system with devices for
sensing, monitoring, and controlling all critical parameters
 Acceptance Criteria:
A typical acceptable range in temperature in the empty chamber is ±15° when the unit is
operating at not less than 250°C.
Endotoxin Challenge Test:
A 3 log cycle reduction or greater is a suitable acceptance criterion for depyrogenation
Fd Value > 30 minutes

22. FH VALUE
The following formula is used to calculate the Fh value in dry
heat sterilization.
Formula: Fh Value (Heat Penetration Factor)
Where,
Δt – Sterilization Hold Time in Minutes
T – Average Temperature of all probes during a sterile hold in °C
z – Temperature Coefficient in °C (20 °C)
The term next to Δt in the above equation is lethality rate.
For steam sterilization, the term right to “T” was 121.1°C
whereas, in dry heat sterilization, it is 170°C.

23. QUESTION
Consider sterilization hold time of 30 minutes at
constant 180°C instead of 170°C, in a similar manner
as above,
Calculate the FH value.?

24. ANSWER
FH Value = 95 minutes

27. CRITICAL PROCESS PARAMETERS FOR
DEPYROGENATION TUNNELS
 Critical process parameters that should be considered during validation and/or
routine processing should include, but are not limited to:
 i. Belt speed or dwell time within the sterilizing zone.
 ii. Temperature – minimum and maximum temperatures.
 iii. Heat penetration of the material/article.
 iv. Heat distribution/uniformity.
 v. Airflows determined by air pressure difference profiles correlated with the heat
distribution and penetration studies.

28. CRITICAL PROCESS PAREMETERS FOR DHS OVENS
 Critical process parameters that should be considered in qualification and/or routine processing
should include, but are not limited to:
 i. Temperature.
 ii. Exposure period/time.
 iii. Chamber pressure (for maintenance of over pressure).
 iv. Air speed.
 v. Air quality within the oven.
 vi. Heat penetration of material/article (slow to heat spots).
 vii. Heat distribution/uniformity.
 viii. Load pattern and configuration of articles to be sterilised/depyrogenated including minimum and
maximum loads.

29. STERILIZATION BY FILTRATION
 If the product cannot be sterilised in its final
container, solutions or liquids should be sterilised by
filtration through a sterile sterilizing grade filter (with
a nominal pore size of a maximum of 0.22 μm that has
been appropriately validated to obtain a sterile filtrate)
and subsequently aseptically filled into a previously
sterilised container.
 The selection of the filter used should ensure that it is
compatible with the product

30. VALIDATION OF FILTRATION
METHOD

31. STERILIZATION BY H2O2
 Sterilization with H2O2 is a low-pressure, low-temperature,
nontoxic process with temperatures typically between 6 °C
and 60 °C that uses vaporized Hydrogen Peroxide to reduce
the level of infectious agents.
 A hydrogen peroxide sterilization process involves filling the
sterilizer chamber with H2O2 vapor. Once the sterilization cycle
is complete, the vapor is vacuumed from the chamber and
converted to water and oxygen.
 The total length of the process can vary depending on the
goods, but typical cycles are between one and two hours.

32. THANKS