The Primary Engineering Control (PEC) provides an ISO Class 5 environment for compounding sterile preparations. A PEC is commonly a hooded work area within an ISO Class 7 buffer room that uses HEPA filtration to maintain ISO Class 5 air quality. There are three main types of PECs: laminar airflow workbenches with horizontal airflow; biological safety cabinets with vertical airflow; and compounding aseptic isolators or containment isolators, commonly called "glove boxes," which have enclosed compounding chambers that can be accessed through gloves. The key difference between compounding aseptic isolators and containment isolators is that containment isolators use negative pressure and can be used for hazardous compounding, while isolators use positive pressure and

1. Primary Engineering Controls
THE BASICS

2. The area required to accommodate the
preparation of CSPs is the Direct Compounding
Area (DCA) located within the Primary
Engineering Control Area (PEC)

3. A PEC is a device or room that provides an ISO
Class 5 environment for compounding CSPs.

4. While a PEC can be a room, it is commonly a
hooded area that is certified to ISO 5 standards
found within the ISO Class 7 Buffer area

5. Conceptual representation of PEC in relationship
to the DCA and Buffer area
Dirtiest
Cleanest
Buffer area
ISO Class 7
PEC
ISO Class 5
DCA

6. PECs rely on high efficiency particle air (HEPA)
filters to maintain ISO Class 5 standards

7. HEPA filters are >99.99% efficient in removing
particles as small as 0.3 microns in size

8. The unidirectional (horizontal or vertical) HEPA-
filtered air provides enough velocity to sweep
particles away from the DCA and maintain
unidirectional flow during preparation of CSPs.

9. PECs typically include
3 types of “hoods”

10. Laminar Airflow Workbenches (LAFWs) – “Horizontal Hood”
Horizontal airflow
Air is drawn in through a
pre-filter before passing
through the HEPA filter.
Filtered air is blown
horizontally across the
hood work surface
Most common “hood”
found in pharmacy IV
rooms

11. Biological Safety Cabinets (BSCs) – “Vertical Hood”
Vertical airflow
Air is drawn in through a
pre-filter before passing
through the HEPA filter.
Filtered air is blown
vertically onto the hood
work surface
Often referred to as a
“chemo hood”

12. Compounding Aseptic Isolators (CAIs) and
Compounding Aseptic Containment Isolators
(CACIs)

13. CAIs and CACIs are commonly referred to as
“glove boxes”

14. CAIs and CACIs have an anti chamber (pass-
through chamber) and a completely enclosed
compounding chamber

15. The anti chamber allows access to compounding
material without exposing contents to outside air

16. CAIs and CACIs are fitted with gloves to
manipulate compounding material inside "the
box“

17. What’s the difference between a CAI and a CACI?

18. CACIs use negative pressure and can be used for
hazardous compounding, while CAIs use positive
pressure and cannot be used for hazardous
compounding

19. USP Chapter <797> states that CAIs and CACIs shall be
placed in an ISO Class 7 buffer area unless they meet
all of the following conditions:
Provides isolation from the room and maintains ISO Class 5 during
dynamic operating conditions
Particle counts sampled upstream of the critical exposure site shall
maintain ISO Class 5 levels during compounding operations
Not more than 3520 particles (0.5 mm and larger) per meter shall
be counted during material transfer

20. JERRY FAHRNI, PHARM.D.