Considering Materials of Construction for USP <800> Compliance
USP chapters <797> and USP <800> use similar language with reference to surfaces inside of a cleanroom and hazardous drug compounding room, so when we consult with architects discussions around acceptable materials of construction are a strict focus. First let’s revisit the language of the USP <800> chapter that states this about the room: “Due to the difficulty of cleaning HD contamination, surfaces of ceilings, walls, floors, fixtures, shelving, counters, and cabinets in the nonsterile compounding area must be smooth, impervious, free from cracks and crevices, and non-shedding.”
There are two different flooring systems that are widely accepted in compounding rooms: Sheet vinyl flooring, epoxy painted and even resinous flooring. Vinyl flooring is probably more recognized in laboratory settings, which is a homogenous sheet of vinyl flooring with heat welded seams so there are no crevices. The current USP <797> chapter states this about flooring: “Preferably, floors are overlaid with wide sheet vinyl flooring with heat-welded seams and coving to the sidewall.” Coving vinyl flooring up the wall in both sterile and nonsterile compounding rooms is absolutely the best practice because cleaning is easier and more thorough. If two walls and a floor converge into a hard 90-degree corner the only way to thoroughly clean is to get down on your knee and meticulously wipe, which further justifies coved corners.
The other accepted flooring material is epoxy paint. It is a two-part (or sometimes three-part) mixing/painting process that creates a really hard and impervious surface. It does take time to thoroughly dry and tends to “off gas” (smell bad) for quite a few days after applied down. If you choose epoxy painted floors let us recommend an after-market coving product to create a radius where the floor meets the wall, again so cleaning is a much easier and thorough process.
Consistent with the walls and ceilings, there are two accepted materials of construction: Cleanable ceiling tiles or epoxy paint over gypsum. If your pharmacy has a sterile cleanroom you are familiar with cleanable/washable ceiling tiles. They are commonly fiberglass reinforced panels (FRP) or vinyl facing panels. Most nonsterile compounding rooms are still using the organic materials-based cork/paper-based ceiling tiles that shed, so moving forward those standard commercial organic materials-based ceiling tiles will not be an accepted material. You will need to replace those with the same tiles that are found in cleanrooms.
Here is one quick word of caution about simply buying cleanable ceiling tiles and hanging them on your existing room’s metal support grid. The cleanable ceiling tiles are two to three times heavier than the standard commercial tile and will probably cause the metal support grid to sag. To counter the sagging, you will consider one of two things: Reinforce the grid with more support wires or better yet, buy 2” metal grid which was made specifically to adequately support the heavier cleanable tiles. As a last piece of advice, make sure the ceiling tiles are either clamped and/or caulked to the gridwork because it will help holding negative pressure and possibly keeping unnecessary particles from being pulled into the negative pressure HD room.
As an alternative to the cleanable ceiling tiles it is acceptable to hang gypsum (also called “drywall”) on the ceiling creating what the construction industry calls a “hard lid.” The hard lid will need to be coated with epoxy paint because that surface will need to be cleaned. There are advantages and disadvantages using gypsum and epoxy paint. The advantage is you get a tighter sealed room to better hold the negative pressure. The disadvantage is that the hard lid limits access to servicing engineering controls like fan filter units (FFU). For this reason, a separate access point will need to be located somewhere else in the facility.
There are quite a few materials of construction that will meet the rule of smooth, impervious, and non-shedding, but let’s first talk about those materials common in today’s compounding rooms that need to be retired. Cabinetry is a common staple in nonsterile compounding rooms and those materials of construction are usually melamine and laminates. The core of those products is pressed fiber board. It is not uncommon to see doors delaminating or damaged, exposing the fiber core as demonstrating in the picture illustration. When this occurs, shedding is inevitable.
It is understandable that people like cabinets, but from a cleanliness perspective, it creates both a physical and psychological barrier. One common argument for cabinet doors is that it creates a physical barrier to keep contamination from resonating in, which is simply untrue. The inside of cabinets where dark 90-degree corners reside are easily neglected during the cleaning process. For these reasons, Bryan always recommends open-shelving in his hazardous drug compounding room design-projects.
There is still some research and debate going on about the four-step process defined in USP <800> section 15. Deactivation, Decontaminating, Cleaning, and Disinfecting so this post will not attempt to tackle that process. Instead we will simply caution you about the reactive nature of certain chemicals as it relates to materials of construction. The current USP <797> chapter has this tidbit of advice for us, “The surfaces shall be resistant to damage by disinfectant agents.” When you purchase tables, countertops, casework, flooring, etc. make sure you ask the vendor for manufacturer supported documentation on chemical compatibility. Because certain chemicals require dwell time on the surface for adequate deactivation and disinfecting, it is advisable to do your research to make sure you will not greatly degrade and ruin the materials of construction over time.