The Advantages of Restricted-Access Barrier Systems - Pharmaceutical Technology

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The Advantages of Restricted-Access Barrier Systems
Filling machines often are installed in sterile rooms and separated by isolators to prevent contamination. These methods have certain drawbacks, including making interventions more difficult. Restricted-access barrier systems are an alternative that ensures sterility and facilitates interventions.


Pharmaceutical Technology


Appropriate guidelines, manuals, and drafts for isolators are available in the three major pharmaceutical markets: the United States, Europe, and Japan. The recently rewritten FDA guidelines, Annex 1 of the European Union good manufacturing practice guidelines, and the detailed PIC/S recommendations are helpful for the planning and use of an isolator (3, 4, 8). The Japanese admission authority also is presently working on an appropriate document.

Classifications of RABS


Figure 4: Machine in an active RABS. The RABS has its own air-handling system that draws air from the area and through openings below the product transport.
RABS are more than just a safety covering for production machines. Incoming air passes through suspended high-efficiency (of at least HEPA Class H14) filters and is distributed evenly by a sterile manifold. The doors of the RABS are locked, and the gloveports are the only means of access. Users must transfer materials and components by means of special aseptic transfer systems. Air flows out of RABS the same way it does with simple barriers: through openings underneath the doors or through holes in the lower sections of the doors. The air returns to the same room from which it came. In a closed RABS, air is prefiltered and recirculated through ducts.

RABS can be classified as either active or passive systems. A passive RABS does not have its own air recirculation, filtering, or conditioning. Its high-purity air supply comes from the cleanroom. Air flows downward from the ceiling and returns to the surrounding room through openings under the doors. The air from the room returns through air ducts to the room air-handling unit (see Figures 3 and 4).


Figure 5: Machine in a passive closed RABS. Air is recycled from the room air-handling system. A prefilter also is used, which helps prevent contamination of the air-handling system.
An active RABS typically has an air-handling unit directly attached to it. This unit always contains a HEPA filter and provides even air-flow distribution with the help of a sterile air manifold. A cooling system also can be integrated for temperature-critical products. Air-conditioning expenditure is limited because fresh air is drawn from the cleanroom (see Figure 4).


Figure 6: Aseptic powder-filling line in passive closed RABS.
A closed RABS is different. Closed RABS also may be passive systems that use the cleanroom's ventilation system and filter ceiling. The air does not return to the surrounding area, it passes through prefilters and ducts into the room's airconditioning system (see Figure 5). Because closed RABS concepts are used with toxic and dusty product applications, operators must pay special attention to cleaning the return air ducts and changing the prefilters without contaminating them (see Figure 6).

Active closed RABS have air-filtration and air-conditioning systems (see Figure 7), which are needed to keep conditions constant within the aseptic area, especially when air cooling is required.


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