13-04-2013, 03:27 PM
Sterilization Methods and the Comparison of E-Beam Sterilization with Gamma Radiation Sterilization
[attachment=53046]
Summary
Sterilization is used in a varity of industry field and a strictly
required process for some products used in sterile regions
of the body like some medical devices and parenteral drugs.
Although there are many kinds of sterilization methods
according to physicochemical properties of the substances,
the use of radiation in sterilization has many advantages
depending on its substantially less toxicity. The use of
radiation in industrial field showed 10-15% increase per every
year of the previous years and by 1994 more than 180 gamma
irradiation institutions have functioned in 50 countries. As
principle radiosterilization utilizes ionizing radiation and is
a terminal sterilization method.
Although gamma irradiation has been used for many years
in sterilization process, electron beam (e-beam) sterilization
is a relatively new process for the sterilization of products,
materials and some pharmaceutical but it is not an official
process yets. Since e-beam was commercialized over 40
years ago, a great deal of research has been performed on its
affects on pharmaceuticals. By products of the process can be
identified and assessed for safety by using some instruments
in analytical chemistry. Consequently radiosterilization is a
better choise for many complex pharmaceutical products that
can not withstand heat or steam sterilization.
STERILIZATION METHODS
Sterilization can generally be defined as any
process that effectively kills or eliminates all
microorganisms like fungi, bacteria, viruses, spore
forms except prions from a surface, equipment, food,
medication or biological culture medium. Although
sterilization can be used in many different fields
of industry, medical and surgical fields are some
of the most important fields that the sterilization is
required but it is strictly required for surgical gloves
and instruments that are used in direct contact with
the blood stream or normally sterile body tissues. It
can also be used for the sterilization of implantable
devices, medical devices (1). Its necessity in using
surgical instruments and medications depend
on their use in body like skin, blood, bone or
some tissues. They should have a high sterility
assurance level (SAL) which is especially important
for parenteral drugs.
RADIATION STERILIZATION
(RADIOSTERILIZATION)
Radiosterilization is a sterilization with an ionizing
radiation (gamma rays) and is a terminal sterilization
method. It has an advantage for applying on drugs
in their final container without any significant rise
in temperature. The first use of ionizing radiation
took place in 1895 and patented in 1921. 25 kGy is
defined as the reference dose that guarantees a
SAL of 10-6 according to Pharmacopoeia. Although
radiosterilization has a variety of advantages, the
mechanism of the formation of final radiolytic
products are still deficient. One of the major drawbacks
of this method is the possible formation of radiolytic
products that leads a change in color and odor of the
product. From pharmaceutical view point, among
different sterilization methods radiosterilization is
the first choice for thermosensitive solid-state drugs.
Chromatographic techniques are the only technique
for determining radiostability of a drug (13, 14).
E-beam sterilization
It is commonly used for the sterilization of medical
devices like gamma radiation sterilization. E-beam
sterilization can be generally made by the use of
e-beams that are obtained from the accelerator and by
isotope method. Its advantage is the need of very short
exposition time depending on the 10 MeV of very
high electron energy. This high energy is fundamental
for an effective sterilization. While 15 min. is sufficient
for the accelerator method, isotope method requires
24 hours. 60Co isotope source is generally used for
the isotope method. The energy of the produced and
accelerated electrons is increased by specially designed
machines. An on-off technology that operates with
electrical energy is used. It is a continuous process. It
can be applied to many materials depending on its
penetration. Immediate release can be done because
it needs no sterilization testing after the completion
of the process. The most important advantage about
e-beam radiation is its having much higher dosing
rate than gamma or X-rays
GAMMA RADIATION STERILIZATION
In the pharmaceutical industry, both the active
pharmaceutical ingredients and the final dosage
forms can be sterilized by gamma radiation
sterilization. The first definition of the sterilization
of pharmaceuticals by gamma radiation sterilization
was declared in USP 30, BP and EP 5 as industrial
sterilization method (2, 3, 4, 22).
E-BEAM RADIATION
E-beam irradiation method is attracting more
attention recently for the sterilization of medical
devices and have many advantages like being safe,
having no emission and high speed processing.
Although low density medical devices be sterilized by
e-beam sterilization generally, high density medical
devices like vessel surfaces can also be sterilized
with high efficiency continuous e-beam sterilization
processing (25).
The ability to control the energy level within the beam
are the reasons for the use of the process commonly.
Although the first use of electron beams had begun
in 1950s in the sterilization, its usage as a sterilization
method in routine became real in 1970s. In 1960s,
e-beam started to be used for medical device packaging
as a safe method. After that time, this process started
to be used more often in medical field depending on
being compatible with a variety of materials. It can also
be used for strengthening some kind of materials. In
this system, electrons are concentrated and accelerated
much higher like speed of light which causes very
quick reactions on molecules or microorganisms on
the product or sample that will be sterilized.
Comparison of sterilization methods and their
applications
When comparing some sterilization techniques,
the doses for the bulk materials for biomedical
applications are in between 10-30 kGy for gamma
radiation sterilization. E-beam radiation has been
successfully used for a large variety of materials
as a bactericide. The only disadvantage for the
sterilization of polymers is that irradiation of them
can cause some molecular bond reactions like chain
breaks, cross-linkings or photo-oxidation reactions.
Besides the radiation sterilization techniques.
CONCLUSION
There is no single sterilization process for all the
pharmaceuticals and medical devices. It is hard to
assess a perfect sterilization method because every
method has some advantages and disadvantages. For
this reason, sterilization process should be selected
according to the chemical and physical properties of
the product. It is fairly clear that different sterilization
processes are used in hospital and in industry
applications. While EtO or autoclave sterilization
is used in hospitals, gamma radiation or e-beam
sterilization is used in industry depending on the
necessity of a developed institution. Superiority of
radiation sterilization to EtO and other sterilization
methods are known by all over the world. These
factors facilitate to understand the reletively fast
increase of the constitution of irradiation institutions.
So, it is unavoidable to become a rapid increase in
the market ratios of radiation sterilization in the
industrial use.
[attachment=53046]
Summary
Sterilization is used in a varity of industry field and a strictly
required process for some products used in sterile regions
of the body like some medical devices and parenteral drugs.
Although there are many kinds of sterilization methods
according to physicochemical properties of the substances,
the use of radiation in sterilization has many advantages
depending on its substantially less toxicity. The use of
radiation in industrial field showed 10-15% increase per every
year of the previous years and by 1994 more than 180 gamma
irradiation institutions have functioned in 50 countries. As
principle radiosterilization utilizes ionizing radiation and is
a terminal sterilization method.
Although gamma irradiation has been used for many years
in sterilization process, electron beam (e-beam) sterilization
is a relatively new process for the sterilization of products,
materials and some pharmaceutical but it is not an official
process yets. Since e-beam was commercialized over 40
years ago, a great deal of research has been performed on its
affects on pharmaceuticals. By products of the process can be
identified and assessed for safety by using some instruments
in analytical chemistry. Consequently radiosterilization is a
better choise for many complex pharmaceutical products that
can not withstand heat or steam sterilization.
STERILIZATION METHODS
Sterilization can generally be defined as any
process that effectively kills or eliminates all
microorganisms like fungi, bacteria, viruses, spore
forms except prions from a surface, equipment, food,
medication or biological culture medium. Although
sterilization can be used in many different fields
of industry, medical and surgical fields are some
of the most important fields that the sterilization is
required but it is strictly required for surgical gloves
and instruments that are used in direct contact with
the blood stream or normally sterile body tissues. It
can also be used for the sterilization of implantable
devices, medical devices (1). Its necessity in using
surgical instruments and medications depend
on their use in body like skin, blood, bone or
some tissues. They should have a high sterility
assurance level (SAL) which is especially important
for parenteral drugs.
RADIATION STERILIZATION
(RADIOSTERILIZATION)
Radiosterilization is a sterilization with an ionizing
radiation (gamma rays) and is a terminal sterilization
method. It has an advantage for applying on drugs
in their final container without any significant rise
in temperature. The first use of ionizing radiation
took place in 1895 and patented in 1921. 25 kGy is
defined as the reference dose that guarantees a
SAL of 10-6 according to Pharmacopoeia. Although
radiosterilization has a variety of advantages, the
mechanism of the formation of final radiolytic
products are still deficient. One of the major drawbacks
of this method is the possible formation of radiolytic
products that leads a change in color and odor of the
product. From pharmaceutical view point, among
different sterilization methods radiosterilization is
the first choice for thermosensitive solid-state drugs.
Chromatographic techniques are the only technique
for determining radiostability of a drug (13, 14).
E-beam sterilization
It is commonly used for the sterilization of medical
devices like gamma radiation sterilization. E-beam
sterilization can be generally made by the use of
e-beams that are obtained from the accelerator and by
isotope method. Its advantage is the need of very short
exposition time depending on the 10 MeV of very
high electron energy. This high energy is fundamental
for an effective sterilization. While 15 min. is sufficient
for the accelerator method, isotope method requires
24 hours. 60Co isotope source is generally used for
the isotope method. The energy of the produced and
accelerated electrons is increased by specially designed
machines. An on-off technology that operates with
electrical energy is used. It is a continuous process. It
can be applied to many materials depending on its
penetration. Immediate release can be done because
it needs no sterilization testing after the completion
of the process. The most important advantage about
e-beam radiation is its having much higher dosing
rate than gamma or X-rays
GAMMA RADIATION STERILIZATION
In the pharmaceutical industry, both the active
pharmaceutical ingredients and the final dosage
forms can be sterilized by gamma radiation
sterilization. The first definition of the sterilization
of pharmaceuticals by gamma radiation sterilization
was declared in USP 30, BP and EP 5 as industrial
sterilization method (2, 3, 4, 22).
E-BEAM RADIATION
E-beam irradiation method is attracting more
attention recently for the sterilization of medical
devices and have many advantages like being safe,
having no emission and high speed processing.
Although low density medical devices be sterilized by
e-beam sterilization generally, high density medical
devices like vessel surfaces can also be sterilized
with high efficiency continuous e-beam sterilization
processing (25).
The ability to control the energy level within the beam
are the reasons for the use of the process commonly.
Although the first use of electron beams had begun
in 1950s in the sterilization, its usage as a sterilization
method in routine became real in 1970s. In 1960s,
e-beam started to be used for medical device packaging
as a safe method. After that time, this process started
to be used more often in medical field depending on
being compatible with a variety of materials. It can also
be used for strengthening some kind of materials. In
this system, electrons are concentrated and accelerated
much higher like speed of light which causes very
quick reactions on molecules or microorganisms on
the product or sample that will be sterilized.
Comparison of sterilization methods and their
applications
When comparing some sterilization techniques,
the doses for the bulk materials for biomedical
applications are in between 10-30 kGy for gamma
radiation sterilization. E-beam radiation has been
successfully used for a large variety of materials
as a bactericide. The only disadvantage for the
sterilization of polymers is that irradiation of them
can cause some molecular bond reactions like chain
breaks, cross-linkings or photo-oxidation reactions.
Besides the radiation sterilization techniques.
CONCLUSION
There is no single sterilization process for all the
pharmaceuticals and medical devices. It is hard to
assess a perfect sterilization method because every
method has some advantages and disadvantages. For
this reason, sterilization process should be selected
according to the chemical and physical properties of
the product. It is fairly clear that different sterilization
processes are used in hospital and in industry
applications. While EtO or autoclave sterilization
is used in hospitals, gamma radiation or e-beam
sterilization is used in industry depending on the
necessity of a developed institution. Superiority of
radiation sterilization to EtO and other sterilization
methods are known by all over the world. These
factors facilitate to understand the reletively fast
increase of the constitution of irradiation institutions.
So, it is unavoidable to become a rapid increase in
the market ratios of radiation sterilization in the
industrial use.