Coatings for effective surface protection

It is critical to achieve and maintain the highest standards of cleanliness and sterility in the pharmaceutical sector. Although many different factors obviously need to be taken into account, one of the most important considerations is keeping walls and ceilings free from bacterial contamination.

Keeping these surfaces hygienic ensures stringent legislation is adhered to and also avoids the risk of cross contamination, as airborne bacteria present during the manufacturing process pose a distinct threat. Pharmaceutical products can be adversely affected if negligible levels of pathogenic micro-organisms or pathogens, toxic microbial metabolites are present, or even if microbial growth has initiated physical or chemical deterioration of the products concerned. The consequences of such contamination can be very serious, and if not detected early, may not be limited to the loss of the product batch in question. Basic building materials, such as cement renders, plaster and brickwork, do not come with surfaces which are easily maintained in a hygienic condition. They are difficult to clean and susceptible to bacterial proliferation between cracks and irregularities in the surface. So to provide the interior of a structure with effective protection against the development of micro-organisms, a wall or ceiling finish must have a surface that is impervious, easy to clean, hard-wearing and free from joints, seams and other features that might harbour dirt and bacteria.

Regulatory demands Indeed, the European Hygienic Equipment Design Group, Directive 93/43/EEC and the Code of Federal Regulations of the Federal & Drug Administration (US) Part 211.42 of the cGMP regulations indicates that walls and ceilings in drug manufacturing premises must have smooth, hard surfaces that are hygienic and easy to clean. In general, this cannot be achieved using open-jointed panels or traditional non-elastic paints or tiles. Because of the joints, panelled systems tend to trap dirt, while non-flexible paints crack and flake when subjected to substrate movement, repeated cleaning or extreme temperature changes. Conventional paints can literally break down after a few months – or even weeks – of application, and they do little to impede mould growth. Even tiles, for so long a natural choice in hygienic environments, are generally avoided due to the difficulty of maintaining the grouting and the health hazards associated with failed grouting and cracked or damaged tiles. Although manufacturers of pharmaceutical products disinfect their premises as a matter of course, most manufacturers like to have the additional assurance that spore lodgement and colonisation simply cannot take place on walls and ceilings. This is done by specifying an aseptic coating with an in-built – but completely safe – film protectant. One company which manufactures an extensive range of waterborne hygiene coatings for application to internal walls and ceilings is Pentagon Plastics, based in Belgium, and part of the UK Iotech Group. These coatings, used by a number of major pharmaceutical companies including Johnson & Johnson (through Janssen Pharmaceutica), Eli Lilly, GlaxoSmithKline and Merck Sharpe Dohme, are designed to meet the highest possible standards of hygiene and decoration for both refurbishment and new works. The coatings contain an anti-microbial system which protects against bacteria, mould (fungus) and yeasts. Independent tests confirm that they protect against bacterial and fungal strains relevant to the pharmaceutical industry, such as MRSA (Methicillin resistant Staphyloccocus aureus), Escherichia sp, Salmonella sp, Penicillin sp, Aspergillus sp and Listeria. Pentagon Plastics' coatings – Steridex, Sterisheen and Sterisept – are quick and easy to apply by brush, roller or airless spray. They do not need any fixings and provide a seamless finish regardless of the shape or complexity of the substrate. This means that there are no joints or fixings in which bacteria can thrive. Furthermore, as the coatings are water based they are hazard-free, as there is no contamination from solvents or strong odour, and they can therefore be used in enclosed locations. These durable, elastomeric membranes are suitable for application to most common substrates including plaster, painted surfaces and ceramic tiles. They are also highly resistant to moisture and can absorb thermal and structural movement without cracking or flaking. With an exceptionally hard-wearing finish much thicker than conventional paints – the film of Steridex is eight times thicker than conventional paint – they can withstand impact from heavy objects and resist massive temperature changes ranging from -50°C to +80°C without impaired performance or cracking. By comparison, ordinary paints are often hard and brittle and are therefore prone to cracking and flaking. As ordinary paints do not have the rubbery properties of Pentagon's membranes, they cannot absorb the movement caused by natural circumstances, such as cleaning regimes.

No leaching In addition, unlike conventional fungicidal paints, the non-toxic fungicidal system in Pentagon Plastics' hygiene coatings will not leach out when subjected to intensive cleaning or humid conditions, and so remain effective against micro-organisms throughout the life span of the coating. The coatings function by acting against airborne spores or colonies; through contact with the hygienic coating, minute amounts of surface active ingredient are absorbed, to ultimately interfere with the enzymatic reproduction process and render the spores invalid. However, as reported by a number of independent laboratories, no active components are released into the atmosphere, ensuring the coatings are safe for use in pharmaceutical environments. The coatings also have the additional benefit of a long life span. With typical life expectancies of at least 10 years – three to four times longer than traditional paints – the coatings do not need replacing at the end of their design lives. When maintenance is eventually needed, their original performance and life span can be maintained by simply applying an additional coat. Resultant cost savings in regular maintenance are significant. All three of Pentagon's hygiene coatings are suited for application to internal walls and ceilings in hygiene sensitive areas, but the choice of product depends upon substrate condition, environmental demands and the preferred surface finish. The main distinction between the three formulations is the range of matt, mid-sheen and gloss options, with total inter-product compatibility to allow total freedom in design and specification. Steridex is a tough, durable, elastomeric, styrene acrylic coating which produces a hard-wearing, high-build matt finish that will tolerate harsh cleaning agents and other chemicals. It can accommodate substantial shrinkage and movement, making it also suited to refurbishment situations where cracks or gaps are in existence. In addition, the product has USDA authorisation and various European registrations. Sterisheen is a medium-build, modified acrylic coating which can be used in areas where a low glare, mid-sheen finish is desired. It has similar biostatic properties to Steridex, but differs in appearance and film build, being closer in consistency to a typical emulsion. Sterisheen is ideal in new build situations, and is also well suited for application to ceramic tiles to provide a totally seamless, hygienic, easily wipeable finish.

Recent launch The company's most recently launched product, Sterisept, a polyurethane/acrylic gloss coating was developed in response to the latest user research. It is extremely fast drying – often curing within 45 minutes – and two coats can be applied on the same working day to achieve a dense, glossy finish which is tough yet flexible. It is therefore ideal for use wherever hygiene is a priority but where work must continue while the application is undertaken. Like Steridex and Sterisheen, Sterisept is available in a wide range of colours, but special colours can also be made to suit specific design/aesthetic requirements. Recent applications for Steridex in cleanrooms and other sterile areas include several tens of thousands of square meters currently being applied at Janssen Pharmaceutica in Beerse, Belgium. While in the Ireland, Steridex was specified for a 15,000m² application at the Pfizer Chemical plant in Ringaskiddy, County Cork and a 4,500m² application has also been completed on behalf of Merck Sharpe Dohme at Clonmel in County Tipperary. In addition to coatings, Pentagon also manufactures a range of ancillary systems, such as bioactive pre-treatment solutions, primers, cleaning agents and a sealant.