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A2 Barrier Isolators as an Alternative to a Cleanroom

The processes used by pharmacist to develop a compounded sterile preparation (CSP) have been criticized over the years because of correlations between the processes and patient injury and death. In particular, methods of sterilization, transfer of CSPs and delivery of CSPs are under scrutiny. Ongoing efforts to reduce the risk to patients and improve the quality of sterile preparations have meet resistance of one form or another. In January 2004, the first enforceable requirements for compounding sterile preparations was published as Chapter <797> of the U.S. standards document, United States Pharmacopeia 27/ National Formulary 22 (USP27/NF22). The requirements insist that a compounding environment be a sterile environment in which the pharmacist is capable to control the risk of microbial contamination as well as the cross contamination of mixtures and compounds. The requirements specifically address the use of cleanrooms and barrier isolators for providing such environments. The differences between cleanrooms and the A2 Pharmacy isolator are as specified below.

Design Differences

Cleanrooms have been used, traditionally, to control the quality of hospital environments, particularly operating room environments. These rooms are designed to minimize and/or eliminate bacteria and bacterial infections in hospital environments. Cleanrooms may include a biological safety cabinet (BSC) of ISO Class 5 (formerly, Class 100) classification or a horizontal laminar airflow workbench (LAFW) to perform compounding processes. The BSC or LAFW is enclosed in a separate room with a Class 1,000 pharmacy classification. Traditional cleanrooms are designed such that they are quite capable to meet the requirements established in Chapter <797>. Cleanrooms, however, are relatively expensive to build and maintain.

As an alternative to cleanrooms, the requirements also specify barrier isolators as units capable to meet compliance. The A2 Barrier Isolator is such a unit. It consists of two chambers. One chamber, the transfer chamber, is used to prepare the background environment of items taken from the general pharmacy area for use in the isolator unit. The transfer chamber is used to clean the air to ISO Class 5 classification. The other chamber, the isolation chamber, is used to actually perform compounding processes. The isolation chamber also provides an ISO Class 5 environment. The door to the transfer chamber and main isolator door are interlocked to prevent both doors from being open at once. The A2 Barrier Isolator incorporates a turbulent airflow system, which allows vertical airflow in the main isolation unit through a high-efficiency particulate air (HEPA) filter and horizontal airflow in the transfer chamber through a second HEPA filter.

The primary design difference between a cleanroom and the A2 Barrier Isolator can be summed as the difference between having to build a specially designed room inside of a specially designed room versus placing a pre-constructed unit inside of a specially designed room. Both systems are capable to provide safe environments for compounding sterile items at risk levels two and three.

Access Methods

A cleanroom offers to minimize outside contamination, not contamination within the room. The front opening of a cleanroom's BSC allows for the entrance of both items and the worker's arm. Access through the opening presents a risk to the worker since residue may escape through the opening. The LAFW, when placed in a cleanroom and operating properly, provides HEPA filters that remove about 99.97% of the internally generated particulate matter, particularly, that which is generated by humans. A motionless human may generate 100,000 particles, per cubic foot, per minute into the cleanroom while a walking person may generate 10,000,000 particles, per cubic foot, per minute. The A2 Barrier Isolator's dual chamber offers glove port access, interlocked doors and negative pressure, which eliminate contamination to and from humans and all other outside sources.

Maintenance

The A2 Barrier Isolator is constructed of one piece of stainless steel with rounded corners for easy sterilization. The glove ports allow access to all internal components of the unit. The unit has an adjustable height system and roller frame, which allows access to all exterior components. The portable isolator unit is much easier to clean than an entire room and all of its components.

Preparations

A report in the American Journal of Health-System Pharmacists, dated July 1999, indicates that the time necessary to prepare items for use in a cleanroom or barrier isolator was not significantly different, once procedures and processes were fully understood. In the documented assessment of oncology products, the turnaround time was approximately 30 minutes. A noted difference was in the cost of supplies necessary to perform level 3, cytotoxic and hazardous drug preparations. The barrier isolation offered cost savings due to a reduced need for gowns and gloves.

The following table summarizes differences between cleanrooms and the A2 Pharmacy Isolator.

Differences Between Cleanrooms and the A2 Pharmacy Isolator

The A2 Barrier Isolator offers electronic controls to monitor the functioning of the unit. An uninterrupted power supply (UPS) backup is used to maintain key isolator functions. Electronic controls are used to monitor:

1. The electrical supply - an audible alarm indicates failure
2. The integrity of vacuum systems - a back up pump is used in the case of failure.
3. The opening and closing of chamber doors
4. Air change rates in both the transfer and compounding chambers
5. Both positive and negative air pressure
6. Leaks in the unit

The A2 Barrier Isolator is also equipped with the following unique components:

1. An adjustable foot pedal for comfort in resting the foot
2. An electronic height adjustment, rather than a manual crank or shaft, which self adjusts each side of the unit.
3. Chambers angled toward the user rather than flat planes
4. Quick release, vacuum-sealed main window and doors rather than hinges or clamps
5. Chambers that automatically adjust to required levels before permitting access
6. Built in validation ports to assess air quality
7. Test points for electronic monitoring and validation and a visual display of results