Obtaining the highest confidence that aseptic cleanrooms and other critical manufacturing/quality control (QC) environments are properly disinfected is paramount in assuring the production of safe and effective pharmaceutical products or medical devices. The microbiological safety of these products is primarily determined by the quality of raw materials used, the integrity of the manufacturing process, and the effectiveness of the disinfection procedures performed in the facility. It is for this reason that the U.S. FDA requires that manufacturers of pharmaceutical and other critical products qualify the disinfection agents and procedures used in these clean environments.

Disinfection in the pharmaceutical, controlled cleanroom space refers to the killing, inactivation, removal or reduction of contaminating microorganisms to levels considered safe per industry standards and regulations. The effectiveness of these disinfectants and procedures is determined by conducting qualification studies in a laboratory setting, which simulate the use procedures and utilize the disinfectants, contaminants and surfaces found within the facility. These qualifications are critical to assuring microbial control in the environment.

How are Disinfection Qualification Studies Regulated?

The success of disinfection procedures used in an aseptic manufacturing environment and the qualification of such processes to complying with GMP’s are not detailed in a simple guidance document. Although there is no harmonized protocol addressing the regulatory requirements associated with disinfection qualification studies, there are several approaches, principles and methodologies outlined in a variety of published sources. Such sources include USP chapters <1072> and <797>, ISO /DIS 14698-(1-3), ASTM E2614 and FDA’s Guidance for Industry: Sterile Drug Products Produced by Aseptic Processing—Current Good Manufacturing Practice.

When Should Disinfection Qualification Studies be Conducted?

The ideal time to conduct a disinfection qualification study is at the construction of the manufacturing/cleanroom facility, prior to operation, when disinfection processes and products are being considered. At a minimum, a qualification should be performed prior to starting full scale GMP manufacturing operations and prior to a regulatory audit. 

How is a Disinfection Qualification Study Executed?

In general, disinfectant efficacy evaluations are made using either suspension-based methods or coupon/surface-based methods.

Suspension-Based Testing

Suspension methods evaluate the reduction of a known organism population inoculated directly into a sample of the liquid disinfectant. Following a predetermined contact time, samples of the inoculated substance are removed, neutralized and evaluated for survivors as compared to an untreated control suspension to provide initial efficacy results.

Coupon-Based Testing

In contrast to suspension-based tests, coupon or surface-based testing is more rigorous and involves the creation of a dried organism film onto 2×2 coupons of each surface type encountered in the manufacturing environment. In the study, the coupons containing the dried organism films are exposed with the disinfectant in a simulated-use procedure. Following a pre-determined contact time, each surface is neutralized and the surviving organisms are enumerated in a quantitative fashion for comparison to untreated surfaces. Survivors found on the treated coupons are compared to survivors recovered on the untreated control coupons to determine the log10 reductions. The level of reduction observed can then be used to assess the success of the disinfection procedure.

Overview of Study Execution

The overall coupon-based testing process is generally executed in six steps:

• Inoculation: Each surface coupon is inoculated with a test organism.
• Drying: Inoculated coupons are placed into an incubator to allow the test organism to dry as a film.
• Treatment: Once dried, each coupon is exposed to the disinfectant by simulating product application.
• Neutralization: Following careful monitoring of the exposure, each coupon is transferred to a preselected solution designed to neutralize the disinfectant and elute, or rinse off, any surviving test organisms.
• Quantitative Recovery: The solution is quantitatively evaluated to enumerate the number of survivors onto an appropriate agar plate medium.
• Analysis: After incubation, the recovery plates are enumerated and the study controls evaluated to assure study validity and calculate log reductions.

Untreated, inoculated, coupons are similarly enumerated to determine the starting level of test organism on each surface type prior to treatment. Appropriate controls should be included with the study to assess the sterility of the materials used in testing and to confirm the adequacy of the neutralization techniques used.

Conclusion

Properly designed, consistently executed disinfection procedures are critical to the production of safe and effective biopharmaceuticals, medical devices and other products. Qualification of these disinfection procedures is required by regulatory agencies as outlined in guidance documented and demonstrated in various warning letters provided by the FDA. Manufacturers ensure the successful design and execution of a disinfection qualification study. Careful review of the data collected in these qualification studies will help facilities monitor potential deficiencies in their disinfection program ultimately ensuring a safer product for the end user or patient.

[Editor’s Note: ATS Labs will be exhibiting at Booth #209 at the 2014 PDA Annual Meeting.]

About the Author

Dave Rottjakob is Director of Business Development and over sees antimicrobial efficacy and disinfection qualification study design at ATS Labs.