There are now numerous design iterations available to hospital pharmacies when it comes to the structure, layout, and functionality of pharmaceutical compounding operations. Decisions must be made regarding the various types of compounding being performed specific to the facility, such as high-, medium-, and low-risk, as well as non-hazardous. One design concept to consider is open architecture, which has its own set of pros and cons, but does offer benefits that were not as readily accessible in the past. The fundamental aspect of open architecture cleanrooms is the ability to perform appropriate (ie, non-hazardous) compounding operations without the use of an enclosure, by utilizing engineered airflow to protect products from contamination. This approach has been gaining ground in hospital pharmacy operations for many years now and is often our first suggestion to a client for non-hazardous compounded sterile preparation (CSP) compounding, especially when the project involves new cleanroom construction. If the pharmacy is considering an open architecture approach to a cleanroom build or remodel that includes integrated, unidirectional vertical laminar flow (UVLF) workbenches, there are several important factors that must be taken into account.

While there can be myriad benefits to an open-architecture approach, the inclusion of UVLF workbenches is not a practical choice for all applications. Most obvious, the configuration is not suitable for hazardous drug compounding. Furthermore, such a design likely will not be successful if the target space for construction lacks the proper clearances above the cleanroom ceiling and behind the compounding areas to allow for the correct installation of high-efficiency particulate airflow (HEPA) units. The space also needs the proper number and placements of low-wall returns required to create the unidirectional airflows demanded for ISO-class 5 work zones as the primary engineering control (PEC).

The Benefits of UVLF Benches
Open architecture designs net more usable compounding space per linear foot compared with traditional PECs, such as laminar flow cabinets. A good general rule is that a five-foot UVLF workbench is equivalent to a six-foot traditional PEC device. Another benefit is that open configurations can easily accommodate automated compounding equipment such as TPN compounders and automatic pumps. From a more abstract point of view, open design also provides open lines of sight, providing the pharmacist supervising technical support personnel with a better view of the activities within the compounding suite. Likewise, the value of telepharmacy cameras or electronic data-capture systems can be enhanced by the open view lines afforded by this design approach. These aspects facilitate a greater degree of patient safety and a higher level of information capture in an area that traditionally has been an exclusively manual domain. Finally, since these configurations offer simple, uncluttered spaces, the cleaning, disinfecting, and sanitation of work surfaces, air foils, and the direct compounding areas (DCAs) that make up the overall UVLF set-up is more efficient and saves labor costs over the equipment’s lifespan.



Specific Design Considerations
Integrating ISO-class 5 primary engineering controls directly into a cleanroom’s architecture involves several key design considerations that must be addressed for the resulting project to be successful:

Room characteristics
Generally speaking, this type of construction should not be considered for locations that lack the ceiling height and room width to allow installation of the duct chaseways necessary for placement of the critical low-wall air returns, themselves required for proper airflow around work surfaces.

Air handling, HEPA and HVAC systems 
Properly directing enough HEPA-filtered air over cleanroom work surfaces is essential to the success of open architecture installations and the design criteria should demonstrate a marked increase in the air-exchanges over traditional construction. For example, a standard ISO class 7 cleanroom (a secondary engineering control [SEC]) designed to accommodate an ISO class 5 PEC must enable 30 or more air changes per hour (ACPH); UVLF work benches require double that baseline number. The ability to generate 60 ACPH is key to effective overall room functionality.

Although the delivery velocity of unidirectional air as it leaves the HEPA filters is not mandated in any industry standard, it is still an important consideration when designing a cleanroom. The ultimate goal is to generate a smooth and constantly sweeping action over the entire work surface, with no dead spots. The delivery velocity (measured at six inches from the HEPA filter face) should range between 90 and 110 feet-per-minute (FPM) with a goal of at least 70 FPM at the work surface. Optimal velocities should be validated with airflow visualization studies (also known as smoke tests) as part of the initial certification process. Unlike traditional PECs, which are smoke tested in their pre-marketing and approval processes, UVLF benches must have in-situ smoke testing video recorded during the initial certification process. Recertification of these UVLF benches should be based upon the delivery velocity near the filter face, not the work height velocity, since it is usually more repeatable.¹

Room components and building materials
Certainly, most typical cleanroom construction materials and methods can be used to create integrated UVLF zones, nonetheless, modular cleanroom construction systems can ease the process. The number of low-wall air returns necessary to create the proper airflows are generally more practical when integrated into a modular cleanroom wall panel. 

One of the most recognizable features of UVLF installations are the airfoils, which need to be mounted to the ceiling grid to direct the airflow down from the HEPA filter faces, over the work areas, and to the work surfaces below. These airfoils must be accessible to allow for regular cleaning and sanitization, as well as inspection during semi-annual cleanroom recertifications. Examples of airfoil material include clear sheet vinyl, Plexiglas, and clear polycarbonate—all of which have distinct attributes, price points, and installation variables. Universally, there should be no gaps between the HEPA filters and walls. Furthermore, any time a horizontal surface appears in a vertical flow of air, a low-pressure zone is created, which can cause turbulence. This turbulence can roil the air, which may result in the introduction of non-HEPA filter air into the direct compounding areas.

Choice of accessories and fixtures 
Since the PEC is integrated into the room, the choice of room fixtures, carts, shelving, and accessories, as well as their spacing, placements, and proper installation is crucial. Stainless steel workbenches should be positioned three to four inches from the back wall of the cleanroom; this placement will allow the air to roll off the back of the table and into the low-wall air returns. As a design element, consider including cleanable spacers or bumpers mounted on the backs of the workbenches in order to maintain the proper distance from the walls. Likewise, workbenches with backsplashes must be avoided. Installing tables with locking wheels will enable easy, in-room cleaning and provide the ability to adjust a table’s position in relation to the back walls and air returns.

Carts also should be mobile, cleanable, and contain only critical goods and compounding supplies, since these items must be regularly moved for room cleaning and sanitization. Seating should be minimal, cleanable, and only included if considered essential in the room set-up.

Consider all available project resources
Depending on the complexity of the project and whether pharmacy has direct access to and assistance from facility engineering and design staff, it may be worthwhile to engage an independent cleanroom design and construction consultant to aid in addressing the range of technical performance criteria over the course of the project’s timeline. Due to the unique nature of open architecture cleanrooms and the required precision of airflow dynamics, not all cleanroom installers or architects have experience with this type of assembly. Perhaps the most common challenge is finding qualified component suppliers and room certifiers experienced in testing and certifying these configurations.² The addition of a consultant experienced in these types of installations can help accelerate the projected timeline, reduce the chance of unforeseen rework, and ensure a smooth transition once compounding operations commence in the cleanroom. 

Adapting Staff Training
Compared to traditional cleanrooms, open architecture configurations provide more linear space, greater freedom of movement, and a greater overall feeling of openness. However, in order to fully realize these benefits, compounding staff must be trained to emphasize disciplined, controlled work patterns, and sound aseptic technique. The use of UVLF workbenches in medication compounding is not widely different from the use of traditional PECs, but as with any new technology, accommodations and adjustments must be built into work practices. Proper material introduction into the ISO class 5 spaces, and drug and material transfers during compounding processes are examples of practices that will differ within an open cleanroom configurations. Due to the open architecture and unfettered workspace, compounding personnel must limit their entries and exits from these spaces. Other training specific to open cleanrooms include emphasis on maintaining glove sanitization discipline and not reaching too far into the ISO class 5 zones as to excessively interrupt the unidirectional laminar airflow. Additionally, it may be tempting to simply place compounding components onto the work surfaces without wiping them first. This practice must also be avoided. With proper education, practice, and firm supervision, all these obstacles can be quickly addressed.  

Ongoing Cost Considerations
When forecasting the cost outlay of an open architecture cleanroom configuration, you cannot simply deduct the costs of traditional PECs from the equation, as additional, fixed costs will likely need to be factored in, including:

• Any additional, ceiling-mounted HEPA units
• Upgrades to air handling and HVAC, if required
• The installation of an airfoil, including the costs of reinforcing the ceiling grid, if required
• Newly required accessories, such as a fixed IV bar
• Stainless steel workbenches and carts
• The initial (and follow up) on-site room certifications

The initial certification tests must include an in-situ smoke test as required by USP General Chapter <797>³ and it must be conducted following the guidance provided by the Controlled Environmental Testing Association (CETA).⁴ Working with a qualified and competent certifier who has experience with these designs is key. These installations must be challenged with a proper smoke pattern test, which must be video-recorded, and the results should be detailed in a narrative report noting the successful creation of a unidirectional laminar airflow of sufficient velocity.¹ Engaging the certifier early on in the project can be helpful, as they can assist in the design and build phases of the project.

Conclusion
While not universally applicable, a UVLF-based installation offers some unique advantages and features for cleanroom operations that make it worthy of consideration. The design of an open room containing just stainless steel work surfaces may appear simplistic, but in actuality, the complex airflow engineering can offer more freedom of movement, more compounding space per linear foot, and enable labor and time savings in cleaning processes when compared to standard configurations. Performance is the ultimate quality indicator, and properly engineered and installed open cleanroom configurations can promote compounding excellence. 

References

1. Wagner J. Integrated vertical laminar airflow design considerations. Pharm Purch Prod. 2010;7(6):6. 
2. Gilmore N. Designing a cleanroom with integrated vertical laminar airflow. Pharm Purch Prod. 2010;7(6):4-7.
3. US Pharmacopeia. General Chapter <797> Pharmaceutical Compounding—Sterile Preparations. Facility Design and Environmental Controls. Rockville, MD.
4. Controlled Environment Testing Association [CETA]. Certification Guide for Sterile Compounding Facilities. CETA-003-2006, Ver. 11 (revised January 31, 2012).

Lou Diorio, RPh, is a principal of LDT Health Solutions, Inc, a quality management consulting company. He is a graduate of Long Island University’s Schwartz College of Pharmacy, where he is also an adjunct professor of pharmacy practice and preceptor of pharmacy students.

David Thomas, RPh, MBA, is a principal of LDT Health Solutions having previously served as the director of information technology operations for SoluNet, LLC. In addition, Dave served as a manager of implementation and technology development for Baxter Healthcare. Prior to his 15-year tenure with Baxter, Dave held hospital practice and management positions for five years. He is a graduate of St. Louis College of Pharmacy.