Aseptic Compounding Isolators

Restricted-access Barrier System (RABS) formerly known as
Aseptic Compounding Isolators (CAI’s & CACI’s)


There are two types of RABS.

  • Compounding Aseptic Isolator (CAI) is specifically designed for compounding pharmaceutical ingredients or preparations. It is designed to maintain an aseptic compounding environment within the isolator throughout the compounding and material transfer processes via positive pressure utilizing a cascading concept. Air exchange into the isolator from the surrounding environment should not occur unless the air has first passed through a HEPA filter.
  • Compounding Aseptic Containment Isolator (CACI) is designed to provide worker protection from exposure to undesirable levels of airborne drug throughout the compounding and material transfer processes and to provide an aseptic environment for compounding sterile preparations via negative pressure. Air exchange with the surrounding environment should not occur unless the air is first passed through a HEPA filter system capable of containing airborne concentrations of the physical size and state of the drug being compounded. Where volatile hazardous drugs are prepared the exhaust air from the isolator should be appropriately removed by properly designed building ventilation.RABS have become an alternative choice for compounding facilities that do not have enough of a budget to turn their entire facility into an appropriate cleanroom suite to meet USP 797 specifications. According to USP 797-2016 isolators shall be placed in an ISO Class 7 buffer area unless they meet all of the following conditions:
    • The isolator shall provide isolation from the room and maintain ISO Class 5 during dynamic operating conditions, including transferring ingredients, components, and devices into and out of the isolator and during preparation of CSP’s.
    • Particle counts sampled approximately 6 to 12 inches upstream of the critical exposure site shall maintain ISO Class 5 levels during compounding operations.
    • Not more than 3,520 particles (0.5 micrometer and larger) per meter cubed shall be counted during material transfer, with the particle counter probe located as near to the transfer door as possible without obstructing the transfer.

    Most manufactures are aware of these guidelines and facilities looking for a more economical way of maintaining USP 797-2016 compliant and have designed their units to perform well within these specifications.

    RABS under the USP 797-2019 version outside of a cleanroom suite can only be used for category 1 CSPs (12 to 24 hour BUD).