IV Room

Class 100 Conditions by Henry Rahe, Technology Advisor, Containment Technologies, Inc.

Sterile products should be prepared in class 100 conditions as defined by Federal Standard 209E (Airborne particulate cleanliness class in cleanrooms and clean zones). We have read this statement many times in publications such as ASHP Technical Assistance Bulletin on Quality Assurance for Pharmacy-Prepared Sterile Products but what does it mean and how can today's hospital pharmacy or home health care facility comply in a cost effective manner? 

The Guideline on Sterile Drug Products Produced by Aseptic Processing, June 1987 prepared by the Center for Drugs and Biologics and Office of Regulatory Affairs, Food and Drug Administration defines two key elements for establishing a quality environment for the handling of sterile products. The first is high microbial quality that is achieved through sanitizing techniques that eliminate microbes present both in the air and on surfaces. This article is focused on the second element, the air particulate quality that is achieved by HEPA filtration of the air to remove particles. 

HEPA filters have the capability of removing 99.997% of the particles of 0.3 micron or larger. A HEPA filter operating in the typical air quality found in a pharmacy (100,000 to 150,000 particles per cubic foot) will produce Class 100 quality air (less than 100 particles per cubic foot). To achieve and maintain Class 100 quality air requires not only the moving of the air through a HEPA filter but also protection of the area from the influx of additional particles that are generated in the surrounding envirotunent. The traditional technique for protection of the critical area is called laminar flow. This is used in hoods and cleanrooms to circulate air in a defined direction which passes through a HEPA filter to remove the particles generated within the controlled environment. 

People generate the most particles in controlled envirorunents. Protection from this contamination source is achieved through protective clothing. 

Today's pharmaceutical operations using cleanrooms require operators to wear protective clothing in the Class 10000 environment that contains the Class 100 critical zones where open product is exposed. The protective clothing consists of a complete gown, mask, goggles, hood and foot covering to reduce particle shedding by the operators. The term "bunny suits" was coined to describe the head to toe appearance of people wearing this type of covering. 

Many pharmaceutical companies are moving away from the traditional laminar flow technology to the use of barrier/ isolation technology because of the cost and procedural problems associated with laminar flow. Barrier/isolation technology achieves Class 100 conditions through the use of HEPA filtration in a closed system with reduced air flow and does not expose the operators to the product zone. 

The use of barrier/isolation technology was introduced into the hospital pharmacy and home health care areas through utilization of equipment such as the Mobile Isolation Chamber approach. This approach has three key elements. The first element is a closed environment that uses solid walls rather than air movement to create a critical zone for product handling. The second is a HEPA filtration system that conditions the air flowing through the unit to remove initial particles and particles that may be generated by the materials being used in the unit. The third is the means by which materials are introduced and people interact with the product being prepared within the unit. 

The closed system created by hard barriers such as stainless steel and plastic for viewing of operations provide an area for preparing IV admixtures and cytotoxics that is contained, protecting both product and pharmacist. The solid barrier eliminates the procedural requirements of a set back from the face of a hood and the placement of materials within the work zone in a manner which does not block the laminar flow. This freedom of placement allows more efficient work flow and productivity equal to, or exceeding traditional hoods. 

The air filtration system of such a closed system is not required to maintain a high velocity to improve a barrier thereby reducing energy cost and noise levels when compared to conventional hoods. The air quality is maintained through the use of HEPA filtration of both entering and exiting air and in many cases the air is recirculated within the unit. A small quantity of air is discharged to maintain a pressure differential between the interior of the unit and the environment in which it is located. This pressure differential is used as a backup if the security of the system is breached. The pressure differential can be positive where product protection is the highest priority or negative as in the case of handling cytotoxic preparations where the protection of the pharmacist is the most critical. This type of unit does not require outside venting for cytotoxic applications. 

The interaction techniques that make a system such as the Mobile Isolation Chamber equivalent to a stand alone cleanroom containing a laminar flow hood, are based on the unit being a closed system during operation. The two elements that make this possible are the airlock and the glove ports. The product introduction using an airlock system to separate the critical area and the outside while allowing additional items to be introduced during operations make the system practical. The glove ports allow the required manipulation of product to take place without exposing either product or pharmacist. 

What is Class 100? is it simply the number of particles of a given size per volume of air. How can a hospital pharmacy or home health care facility meet the requirement for 100 conditions? There are two techniques; laminar flow or barrier/ isolation technology. The decision on which method to use should be based on cost effectiveness and flexibility. 

Lehigh Valley Industrial Park #4
The Micro-Clean Company ®
54 South Commerce Way, Suite 160
1-800-523-9852