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LEARNING CENTER
STERILIZATION VALIDATIONS: Radiation Sterilization

Several AAMI/ISO methods are available for validation of the radiation dose used to sterilize a medical device. All of the methods use product bioburden enumeration and a bioburden organism resistance sterility test which is referred to as the verification dose resistance experiment.  The most appropriate methodology is selected based on the projecte production schedule and size. The four most commonly used methods are summarized below.

When planning a radiation sterilization validation, be sure to manufacture enough samples for the entire validation study. Depending on the product’s availability and complexity, an initial validation study can generally be completed in 6 to 8 weeks. Cost is contingent on product size and complexity.

ANSI/AAMI/ISO Methods and dose validation requirements


AAMI TIR 33 VDmax (For Frequent or Infrequent Production Batches)

AAMI TIR 33, Sterilization of health care products – Radiation Substantiation of a selected sterilization dose – Method VDmax,is used to establish a minimum sterilization dose for products manufactured frequently or infrequently in large or small batches. A minimum sterilization dose of 15, 17.5, 20, 22.5, 25, 27.7, 30, 32.5, or 35 kGy is selected based on the product’s average bioburden. For the validation of a single lot, 10 products are tested for bioburden and then a verification dose resistance experiment is performed on 10 products irradiated at the calculated verification dose (or 20 products if growth occurs in two of the first 10 tested). For frequently produced lots, the initial validation includes bioburden testing of 10 products from each of three separate lots and then a verification dose resistance experiment on 10 products from one lot. Revalidation consists of quarterly bioburden testing of 10 products followed by a verification dose resistance experiment on 10 products from the same lot.

ANSI/AAMI/ISO 11137-2 Method 1 (For Large and Frequent Production Batches)

Dose Setting Method 1 outlined in ANSI/AAMI/ISO 11137-2, Sterilization of health care products—Radiation-Part 2: Establishing the sterilization dose, is the validation method most commonly used for products frequently manufactured in lots of greater than 1000 products and when a minimum sterilization dose is desired. The initial validation includes bioburden testing of three separate lots and a verification dose resistance experiment on 100 samples from one lot irradiated at the calculated verification dose. Revalidation consists of quarterly bioburden testing of 10 samples followed by a verification dose resistance experiment on 100 samples from the same production lot.

ANSI/AAMI/ISO 11137-2 VDmax (For Frequent or Infrequent Production Batches)

ANSI/AAMI/ISO 11137-2, Sterilization of health care products—Radiation-Part 2: Establishing the sterilization dose, is used to establish a minimum sterilization dose of 15 kGy for products with an average bioburden <1.5 CFU or 25 kGy for products with an average bioburden <1,000 CFU. The number of devices required to conduct a validation is the same as indicated under AAMI TIR 33 – VDmax.

AAMI/ISO 15844 (For Large but Infrequent Production Batches)

AAMI/ISO TIR No. 15844, Sterilization of Health Care Products—Radiation Sterilization—Selection of a Sterilization Dose for Single Production Batch, provides a radiation validation procedure when only one lot of product with a lot size greater than 1000 is produced. This document is used in conjunction with AAMI/ISO 11137 to establish a minimum sterilization dose based on bioburden testing of 10 samples and a verification dose resistance experiment on 100 samples from the single lot.

 

 
 
 
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