The Gamma Sterilization Process
Gamma is a very effective method for
sterilization of both low and high density
products.
It is especially recommended for products that
are impermeable to air exchanged like pre-filled
syringes.
The failure of gaseous exchange would otherwise
make methods like Ethylene Oxide (EO)
sterilization ineffective.
The Gamma process is confirmed by verifying the
dosimeter reading following exposure.
This is considerably quick in relation to the
use of biological indicators as is used in EO. Additionally, the Gamma process does not result in residues.
Prior to determining if Gamma is right for your
product you should send several samples to get
irradiated to determine compatibility.
Validating The Gamma Sterilization Cycle
The current method for validating the Gamma
process can be found in the standard
ANSI/AAMI/ISO 11137, "Sterilization of
Healthcare Products—Requirements for Validation
and Routine Control—Radiation Sterilization."
As in EO Sterilization the Gamma process
requires that you establish a Sterility
Assurance Level (SAL).
A recognized SAL is
10-6,
or a one in a million chance that a product will
remain non-sterile.
The objective is to establish the minimum dose
required to bring about the required SAL.
The two basic methods used in Gamma
sterilization validation are bioburden and bioburden resistance methods. The former is a quantitative method that relies on the number
of microorganisms on the product.
The later is based on the qualitative resistance
of the microorganisms to gamma radiation.
The bioburden resistance method is preferred
since it is based on the types of microorganisms
on the product, whereas the bioburden method
relies on a theoretical determination of
sterility.
As in any good sterilization program regular
determination of bioburden from non-sterilized
products should be conducted regularly.
Population deviations should be investigated to
determine the likely cause.
The manufacturer may have to revalidate the
sterilization process to take into account this
change in the product life cycle.
Standards for Gamma Sterilization
|
Standard
|
U.S.
|
Europe
|
ISO Standard
|
|
Validation Sterilization Methods 1
and 2
|
AAMI |
EN 552
|
11137
|
|
Validation sterilization small lots
and |
AAMI/ISO TIR |
N/A
|
N/A
|
|
Microbiological sterility
|
AAMI TIR |
N/A
|
11737-2:
|
|
Estimation of population
|
AAMI TIR |
EN 1174
|
11737-1
|
