The Aseptic Room
All openings except the openings for entry need perfect sealing and
horizontal surfaces including windows should be eliminated. These
surfaces may allow retention of dust and may create problems.
The structure should be tight enough to prevent infiltration of
uncontrolled air. All exposed surfaces should be smooth and impervious,
easily cleanable and in no way prone to settling of dust upon them.
The surfacing material should not be susceptible to hold dust,
flaking or chalking under normal operative procedures. Uncoated smooth
surfaces e.g. stainless steel, aluminium and chromium plating, plastic
laminates and plastic films make satisfactory surfaces. Cement concrete
is a very undesirable surface.
In view of the sealed structure, preventing any source of entry of
air, air conditioning is essential. Since no special requirement of
temperature and humidity are prescribed, conventional air conditioning
may be suitable enough. It is however preferable to have the humidity on
the lower side to avoid contamination by the perspiration of the
Air cleaning part of the air conditioning system is a critical factor
as the nature of the atmospheric air may differ considerably from time
to time. Cooling and heating coils, humidity control apparatus, reheat
coils; blowers etc. are the equipment that should be of standard
However, the fans selected should be such that can provide high
pressure. The room has to be constantly maintained under positive
pressure to prevent inlet of air from entry point whenever it is opened.
Dust, temperature and humidity control are interdependent functions.
Dust control is impossible without confining the area. Confined space
is unlivable without air-conditioning. If temperature and humidity are
controlled by air conditioning, dust control measures are automatically
taken care of.
Cleaning of Air
Cleaning of air is the key factor of the aseptic processing. The
usual approach is a combination of the conventional cleaners e.g.
regular filters or electronic air cleaners located within the system and
some kind of super-interception or an ultra cleaner located down stream
from all coils, blowers etc.
Bactericidal equipment is incorporated in the assembly for providing
sterile air in addition to be devices stated above. The air in the
aseptic area should be free from fibers, dust and microbes. This can be
conveniently achieved by the use of High Efficiency Particulate Air
(HEPA) filters which can remove particles up to 0.3 µm with an
efficiency of 99.7% or more.
HEPA filters made use of in Laminar Air Flow in which air moves with
uniform velocity along parallel lines with minimum of eddies. The air
flow can be either horizontal or vertical and 100 ± 10 ft/min. is
considered to be the minimum effective air velocity. Such laminar flow
stations and work benches are commercially available and should find
immense use in compounding and dispensing practice.
Materials of construction for the air distribution system should be
made of non-rusting and non- flaking materials (e.g. ducts, air outlets
etc.). Duct insulation, if needed, should be applied on the outer side
and only on the ducts that are located out of the clean area. Joints and
other fittings, if any, should be sealed to prevent leakage and
contamination. Air distribution is also employed for 'washing' the
workers off dust who enter the sterile area. These are called air
showers which are strictly blasts or air directed on the person to
Conventional controls are used in the system for regulating humidity
and temperature. Sometimes greater pressure may have to be maintained in
critical areas and for this purpose additional controls may have to be
installed. Interlocks may be required between the sterile area and the
entrance or passing doors. In a highly elaborate system, alarm circuits
are introduced to warn against the malfunctioning or inadvertent misuse
of the air locks.
Highly sophisticated instrumentation has to be installed which
constantly or intermittently monitors and samples the clean atmosphere
for analyzing its cleanliness. These devices immediately indicate the
contamination, if any.
Seating, work tables, racks etc. are essential requirements of
furniture inside he clean area and have to be specially designed and
built to meet certain rigid specifications. Adjusting mechanisms on the
chairs should either not exist or ought to be sealed. These may be
potential dust setting surfaces.
Conventional upholstering of the chairs is completely out of
question. Dust catching surfaces should be minimum and all parts should
be readily cleanable and resistant to the action of the cleaning agents.
Worker comfort is a very important factor in a confined area. The
requirements of the job in a sterile room keep the workers chained to
the work over long periods of time continuously without leisure and with
minimum exits from the room and thus warrants high degree of comfort
for carrying out the critical operations.
Special jigs, fixtures and tools are developed for specific purposes
but many operations need dust-free hoods-miniature aseptic rooms located
on the working bench. Even when the aseptic hoods or chambers are
located in dust free rooms, they may have to be provided with supply of
pressurized air in each one of them. The air may be either super cleaned
or an inert gas. Further these hoods have to be independently
There are many several important factors to consider when called upon
compounding a sterile ophthalmic preparation. Eyes are very sensitive
to heat, light, drugs and chemicals. In many cases, the drugs involved
have a narrow therapeutic range and even small errors when introduced
have the potential to cause irreversible damage to the eye or loss of
the eye sight. The following considerations are recommended whenever
preparing such a product.
1. Ensure concentration is within the acceptable range or not before dispensing of the product.
2. Sterility of the final product is a must, strictly handled in aseptic area.
3. The pH of the final product must be within an acceptable range.
4. Stability of the final product must be known, as well as the recommended storage requirements.
5. Suitable knowledge of potential diluents or vehicles is required
in order to ensure proper tonicity, viscosity, or dissolution of the
6. Proper documentation of each step is an important consideration to reduce error.
7. If the preparation of a product requires the breaking of an
ampoule or the reconstitution of a powder, it is recommended that the
final product be made in sterile water for injection and free from
8. The preparation of intra-occular products requires the use of
preservative-free ingredients. Many preservatives have been found to be
toxic to the inner ocular tissues.
9. Finally, before dispensing the finished product, always indicate
the storage requirements, concentrations of ingredients, and the
expected expiration date.