Disinfectant selection

Maintaining the cleanliness of a pharmaceutical manufacturing cleanroom is paramount if the products being made are not to be compromised.

The selection of an appropriate disinfectant for critical areas should not be like picking a product from a supermarket shelf, nor undertaken as a knee-jerk reaction to a problem. It should be made on the basis of: • An environmental survey of the facility and historical environmental data • An understanding of the chemistry of disinfection • Efficacy data supplied by the manufacturer and generated in-house • Compliance with standard testing procedures, like the new harmonised European Standards • Quality control, documentation and certification • Performance in terms of ease-of-use and speed of action • Health and safety

Efficacy, performance and assured sterility are essential for controlling contamination. Current regulatory standards now stipulate that disinfectants used to control contamination in Grade A and B pharmaceutical preparation and filling areas must be sterile prior to use.¹ Many institutions still produce sterile disinfectants in-house. There is a hidden cost for the pharmaceutical manufacturer in this however, because running costs, cleanroom time and "missed opportunities" are all expensive. There is much to be gained from purchasing disinfectants manufactured to GMP guidelines either in a ready-to-use format or a format requiring minimal end-user processing. It is now possible to select disinfectants specifically designed for cleanroom use that have been subjected to the necessary rigorous manufacturing protocol and quality control checks. Moreover, these disinfectants are presented in a variety of formats most suited to the cleanroom environment and are packaged for easy introduction into the cleanroom without risking the entry of externally borne micro-organisms. The following example of a recently conducted selection and validation process by a unnamed but major pharmaceutical company for a facility in Europe provides information that is relevant to any organisation operating cleanroom environments. This particular facility was undergoing expansion of its manufacturing areas with a brand new Grade B cleanroom. The company was unhappy with the established disinfection protocol and the microbiologist was under pressure to initiate a change; mainly on the basis of health and safety, but also because the existing contamination control procedure incurred lengthy production downtime. It had already been criticised in an FDA audit for not undertaking independent evaluation of its current disinfectants by standard methods and against facility isolates.

Existing procedure The procedure historically employed by this facility was three weeks of using an amphoteric disinfectant at 0.5% v/v concentration, then swtiching to 1% v/v concentration of a formaldehyde/ glutaraldehyde/ quaternary ammonium compound mixture on week four. When there were conditions of heavy soiling then the formaldehyde/glutaldehyde/quat blend was utilised by fogging at a concentration of 8% v/v. This is much higher than the recommended 3% v/v because it was found to be ineffective against the B.licheniformis isolate. The fogging process was costly in terms of production time and presented a considerable health hazard. Extensive rinsing was also required between the rotational products, because a sticky residue was being generated. The process of agreeing a new disinfection policy was divided into four steps:

Step 1 – Environmental history: Air and surface testing of an aseptic area is required under GMP. This information identifies the organisms present in the various areas of the aseptic manufacturing environment. In this facility, the data indicated routine observation of a Micrococcus species, S.epidermidis and two Bacilli species, one of which appeared to be the particularly resistant B.licheniformis. No moulds or fungi were observed.

Step 2 – Prime requirements from a disinfectant: Armed with the environmental information, the facility formulised the points it required of a disinfection protocol and what its ideal would be. These included: • A rotational system • One of the rotations including a sporicide • Safety for their operators • Residues and compatibility of materials • Ongoing manufacturer's support

Step 3 – What choice does the microbiologist have? A shortlist of three rotational combinations was drawn up for further consideration: A. The current disinfectants: an amphoteric and formaldehyde/ glutaraldehyde/quaternary ammonium compound B. A rotational pair consisting of acid and alkaline phenolics, with occasional use of a hydrogen peroxide/peracetic blend as a sporicide C. A rotational pair consisting of a quaternary ammonium compound blended with a biguanide, and stabilised chlorine dioxide blended with a quaternary ammonium compound (this being a sporicidal substance)

Details of the chemistry and efficacy of these agents are shown in table 1. The inclusion of a sporicide was important to this company. The advantage of the stabilised chlorine dioxide/quat blend is that it is very fast-acting and can be used at concentrations that are safe to handle, meaning it can be used on a routine basis with little loss of production time. In option B, the peroxide/peracetic agent was found to be expensive and could only be considered for use on an occasional basis, therefore three agents would have to be approved. The formaldehyde/glutaralde-hyde blend was considered to be harmful to the operators and the company aimed to stop using the product. Further technical information was requested from the manufacturers and they found that the presentation of the material was of variable quality; in some cases it was difficult to extract the relevant data. Technical information should include: • Product specifications • Examples of certificates • Sterility assurance • Material safety data • Raw materials specification • The production process • Validation • Efficacy • Residues • Materials compatibility

Step 4 – Testing: All the shortlisted options were evaluated in-house to assess their effectiveness and ease-of-use. By far the most popular combination was option C – the stabilised chlorine dioxide/quaternary ammonium blend and the quaternary ammonium / biguanide blend. This option was considered to be far safer and more pleasant to handle than some of the other disinfectants available. A sporicide was part of the rotation, unlike option B, which required an additional agent. The preference was to move away from fogging as this would significantly reduce lost production time: this could be achieved with option C. The disinfectants were tested against European standard methods EN1276 and EN1650, both of which are suspension tests carried out with an interfering substance of bovine serum albumin. Under the conditions of EN1276, the disinfectant must demonstrate at least a log 5 reduction against P.aeruginosa, E.coli, S.aureus and E.hirae. The contact time for the test was five minutes at 20°C.

Testing scheme To be considered fungicidal, the conditions of BS EN1650 require demonstration of at least a log 4 reduction against C.albicans and A.niger. The test contact time was 15 minutes at 20°C. The facility isolates submitted were identified as Micrococcus species, S.epidermidis, B.cereus, and the resistant B.licheniformis. Against the referenced strains, the disinfectants achieved the required log reduction in viable count in five minutes. A log 5 reduction was also achieved against Micrococcus species and S.epidermitidis isolates. At the time of testing there was no European Standard for determining sporicidal activity. However, considered opinion suggested that, for a disinfectant to be considered sporicidal, it should achieve a greater than a log 3 reduction within 15 mins at 20°C and in the presence of 0.3g/l bovine albumin in suspension. The Bacillus species were tested under these criteria but with a contact time of only five minutes. A log 3 reduction was achieved. The test clearly indicated that the product consisting of a stabilised chlorine dioxide blended with a quaternary ammonium compound was not only an extremely effective sporicide, but also that it became effective quickly and at concentrations that presented no hazard to the operators. At the time this study was carried out there was no published European surface test method. The EN testing programme has now been extended to include a suspension test for spores (EN13704). There is also now a surface test which can be used for bacteria, fungi and moulds (EN 13797), but still no surface test for sporicidal activity. A test programme should now include surface testing, as well as the suspension tests mentioned above, as it gives a more accurate representation of how the product would be used in practice. Having received a comprehensive test report and considered all the issues, the pharmaceutical facility concluded that option C was the most effective – namely the rotational pair consisting of a quaternary ammonium blended with a biguanide, and stabilised chlorine dioxide blended with a quaternary ammonium compound. A protocol was prepared for the commissioning of the new facility. Following this and adequate ongoing environmental monitoring, the new protocol will be incorporated throughout the site. This case shows that a new disinfection protocol can be established in a relatively quick timeframe, if: • The companies' requirements are clearly established at the onset • The steps required are clearly identified and followed • Good quality information and support is provided by disinfectant manufacturers • A reliable, accredited test-house is included in the evaluation.