Dry-Heat Sterilization Methods Focus of Draft Standard

Originally Published MDDI August 2002

NEWS & ANALYSIS

Gregg Nighswonger

A proposed AAMI/American National Standard provides specific requirements and guidance for using a sterilization process for healthcare products that could be adversely affected by more common modalities. The process, dry-heat sterilization, was the subject of previous traditional recommendations, standards, and guidance documents that were developed for clinical applications.

Wayne Rogers, a materials-safety and sterilization consultant in Temecula, CA, says this is an important new standard because it specifically targets medical devices. "Previous standards had been developed for hospitals and dental offices," he says, but not for medical devices. Rogers explains that FDA defines reliable dry sterilization as classic dry-heat processing that occurs at 160° to 180°C. "Anything outside these conditions must be developed, qualified, and validated as a new process," says Rogers.

The use of dry-heat methods to sterilize materials and surfaces has proven effective in both medical and nonmedical applications—including medical prostheses, implants, and even spacecraft. The process involves exposing the product to hot air circulated in a chamber. The effectiveness of the process is based on both temperature and duration of exposure. The method has been shown to be well suited for materials that are heat stable, but that are sensitive to moisture, resistant to penetration by steam heat, or prone to radiation damage.

Rogers suggests, however, that dry heat could be used to treat products with less heat than traditionally recommended (105° to 135°C). "Reducing the sterilizing temperature [allows] many more polymers, materials, and electronics to be processed and sterilized than can be through more traditional methods," says Rogers.

AAMI's proposed draft standard, "AAMI/DS-1 ST63—Sterilization of healthcare products—Requirements for the development, validation, and routine control of an industrial sterilization process for medical devices—dry heat," outlines the requirements and provides guidance for the development, validation, and routine control of a dry-heat sterilization process for medical devices.

"The new standard appears to be flexible enough for new medical device firms to develop, validate, and control," says Rogers. "It's similar to standards for steam and EtO sterilization." Nevertheless, Rogers suggests that those drafting the new dry-heat sterilization standards should consider alternative approaches similar to those developed for radiation sterilization.

Copyright ©2002 Medical Device & Diagnostic Industry