This third paper on the history of isolators describes the development and use of non-flexible film isolators including restricted access barrier systems (RABS). By non-flexible is meant that type of unit that has a metal or a rigid plastic structure. These are referred to as conventional isolators. Many of these models have been designed to enclose various types of filling machines for processing vials, ampoules, cartridges or syringes and are the descendants of glove boxes or safety cabinets for aseptic processing.
RABS appear to have been largely devoted to aseptic filling of various forms of vial and syringe or filling products for terminal sterilisation and are dependent on unidirectional airflow as in conventional clean rooms. Other such isolator models have been used for handling, processing and compounding pharmaceutically active materials and for enclosing small tanks, washing utilities, analytical instruments, etc. Some of the flexible film units such as sterility testing or for hospital pharmacy use have also been replaced by rigid versions. One addition to mention is the preparation and compounding of radio-active products.
As can be seen in Figure 1, early aseptic filling was primitive by today’s standards.
It was in the 1930s and afterwards that glove boxes came into use for similar purposes as shown in Figure 2.
Glove boxes continued to be used with modifications that eventually included some form of air filtration.
It was not until after World War II that HEPA filters became available and the traditional cleanroom concept emerged. The cleanrooms were based upon unidirectional airflow over the filling area and have remained so ever since. Improvements to avoid the effect of air displacement by operator movements led to screening with sheets of hanging flexible plastic, see Figure 3.
“The cleanrooms were based upon unidirectional airflow over the filling area and have remained so ever since.”[…]
A courtesy of ‘Clean Air & Containment Review’ – www.cleanairandcontainment.com
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- author: Thorogood Doug