1. Sterile preparation Facilities and Equipment Biological Safety Cabinet
Laminar Airflow Hood
Biological Safety Cabinet

2. Why Laminar Flow Cabinets?
Laminar Flows
Laminar air flows can maintain a working area devoid of contaminants.
Many medical and research laboratories require sterile working environments in order to carry out specialized work.
Why Laminar Flow Cabinets?
Laminar Flow Cabinets create particle-free working environments by projecting air through a filtration system and exhausting it across a work surface in a laminar or uni-directional air stream.
They provide an excellent clean air environment for a number of laboratory requirements.

3. All operations and manipulations must be performed under a certified laminar flow hood equipped with HEPA filtered air.
Working in a laminar airflow (LAF) environment can never replace the necessity for rigid clean technique in sample preparation and analysis.
Prior to conducting a test, the hood must be cleaned with an appropriate solvent, preferably 70% ethanol or 70% isopropyl alcohol.
The HEPA filter itself is not cleaned because of potential damage to the filter surface.

4. HEPA filters It used to clean the air entering the clean room .
These filters remove all airborne particles 0.3 nm or larger, with an efficiency of 99.97%.
HEPA filtered room are classified as ISO class 3-8 .
An ISO class 8 room contains no more than 3,520,000 particles of 0.5mm or larger per cubic meter of air.

5. Positive pressure airflow
It is used to prevent contaminated air from flowing in to the clean room.
The air pressure inside the clean room must be greater than the pressure outside room, so that when a door or window to the clean room opened, the air flow is outward.
The air flow moves with a uniform velocity along parallel lines. The velocity of the air flow is 27m/min ( 90 ft/min).

6. How They Work?
Laminar Flow Cabinets work by the use of in-flow laminar air drawn through one or more HEPA filters, designed to create a particle-free working environment and provide product protection.
Air is taken through a filtration system and then exhausted across the work surface as part of the laminar flows process.
Commonly, the filtration system comprises of a pre-filter and a HEPA filter.
The Laminar Flow Cabinet is enclosed on the sides and constant positive air pressure is maintained to prevent the intrusion of contaminated room air.

7. The Use of Equipment in the Laminar Airflow Hood
The USP demands the use of “scrupulously” clean glassware and equipment.
The word “scrupulous” means the following:
1. Rinse glassware and equipment successively with (i) warm detergent solution, (ii) hot water, (iii) water, and (iv) isopropyl alcohol. The first supplement of the 19th edition of the USP listed a fifth rinse with trichlorofluoroethane (Freon 113). Freon was eliminated in the 20th edition procedure because of concern about its toxicity in a closed environment, and harm to the ozone layer.

8. 2. Rinsing technique is important
2. Rinsing technique is important. Glassware and equipment must be rinsed starting at the top of the vertically held object and working downward in a back-and-forth manner.
Water rinsing may be done outside the LAF hood, but the final isopropyl alcohol rinse must be performed within the hood.
3. After rinsing, all objects must dry under the HEPA filter air in hood. This helps to remove extraneous particles adhere to the drying object.

9. Types of Laminar Flow Cabinets
Laminar Flow Cabinets can be produced as both horizontal and vertical cabinets. There are many different types of cabinets with a variety of airflow patterns for different purposes.
Vertical Laminar Flow Cabinets
Horizontal Laminar Flow Cabinets
Laminar Flow Cabinets and Hoods
Laminar Flow Benches and Booths
All ensure a work space devoid of contaminants and may be tailored to the lab requirements.

10. Horizontal Laminar Flow Cabinets
Horizontal Laminar Flow Cabinets receive their name due to the direction of air flow which comes from above but then changes direction and is processed across the work in a horizontal direction. The constant flow of filtered air provides material and product protection.
Vertical Laminar Flow Cabinets
Provide two major advantages over horizontal flow hoods:-
Air flow is vertical, flowing down on the work space. This airflow pattern protects the operator against potential hazards from the products being prepared .
A portion of the HEPA filtered air is recalculated second time through the HIPA filter. The remainder of the filtered air is removed through an exhaust filter, which may be vented to the outside to protect the operator from chronic concentrated exposure to hazardous materials.

11. Laminar Airflow Hood Basics
A laminar flow hood has three basic functions.
The first is to provide clean air in the working area by passing room air through a bacteria-retentive filter to provide a continuous flow.
Second, the constant flow of air out of the laminar flow hood prevents room air from entering the work area.
Last, the air flowing out suspends and removes contaminants introduced in the work area by material (such as IV bags, syringes, and drug packaging) or personnel.
Thus, the laminar flow hood provides an environment virtually free of airborne contaminants, in which procedures can be safely performed.

12. Laminar flow hoods may be used in the pharmacy to perform the following procedures:
Preparations of IV admixtures
Preparations of ophthalmic solutions
Reconstitution of powdered drugs
Filling unit dose syringes
Preparation of miscellaneous sterile products.
Laminar flow hoods come in various sized and models. One model, called a console model, sits on the floor. The other common model is called a bench or countertop model, because it sits on top of the counter, and the space underneath it can be used for storage space.

13. Both the console and bench models are available with vertical rather than horizontal airflow.
Precautions
Laminar airflow hoods are usually kept running continuously. If the hood is turned off, it is recommended to run for at least 30 minutes before using the work surface area in order to replace the room air with clean, filtered air.
Laminar flow hoods should be inspected and certified every six months to assure that the HEPA filter is intact, unclogged, and has no holes, leakage in it.
The prefilters in the hoods should be changed monthly.

14. Cleaning Laminar Airflow Hoods
Cleaning the laminar airflow hoods may be done with a non-shedding wipe or sponge dampened with Water for Injection, with or without mild detergent.
This should be followed by:
70% of isopropyl alcohol (or another appropriate disinfecting agent) should be used to clean all interior working surfaces before each use.
A clean, lint-free cloth should be moved in a side-to-side motion, beginning at the rear and moving toward the front of the LAH.

15. 3. The walls of the LAH also must be cleaned from top to bottom with 70 percent isopropyl alcohol.
This procedure should occur often throughout the compounding period and whenever the work surface becomes dirty.
Because some materials require water to remove them, these materials may be first cleaned off with water, followed by the alcohol or other disinfecting agent.

16. Laminar flow cabinets may have a UV-C germicidal lamp to sterilize the interior and contents when not in use. (It is important to switch this light off during use, to limit exposure to skin and eyes as stray ultraviolet light emissions can cause cancer and cataracts

17. Biological Safety Cabinets
Since horizontal laminar-airflow hoods blow air toward the operator, So, vertical laminar airflow hoods are preferred when working with hazardous substances.
Vertical flow hoods are part of a family of equipment called biohazard cabinets or biological safety cabinets.

18. Three types of biohazard cabinets are available:
1. Class I cabinets have a HEPA filter on their exhaust outlet but not for inward airflow. They protect personnel and the environment but do not prevent contamination of compounded preparations. This class of hoods has no application in compounding sterile preparations.

19. 2. Class II cabinets have HEPA filtered inward air for protection of compounded preparations and HEPA filtered exhaust air to protect personnel. They are suitable for compounding sterile preparations.
Class II cabinets are classified according to how their exhaust air is vented.

20. 3. Class III cabinets are totally enclosed, vented, and gastight units
3. Class III cabinets are totally enclosed, vented, and gastight units. Operations are conducted through attached rubber gloves, and the cabinet is maintained under negative pressure. These cabinets have limited applications in the preparation of sterile products and are intended for the handling of extremely hazardous substances.

21. A biological safety cabinet functions by having air taken into the unit at the top, where it passes through a prefilter to remove large contaminants.
Air then passes through a HEPA filter and is directed down toward the work surface, just as with a vertical laminar flow hood.
The filter forms the ceiling of the work area in the biological safety cabinet and removes bacteria to provide ultraclean air.
A major portion of the contaminated air is recirculated back into the cabinet, and a minor portion is passed through a HEPA filter before being
exhausted into the room.

22. Hood Selection.
Vertical laminar airflow hoods are the preferred choice. These cabinets prevent cumulative exposure to potentially toxic medications, especially if the staff routinely compound hazardous preparations for a long time.
When sterile preparations are compounded, aerosols can form and be blown toward the operator using a horizontal hood.
Long-term exposure to cytotoxic agents as well as other drugs, especially antibiotics, is a great concern. Vertical airflow hoods minimize such exposure.
The disadvantage of vertical airflow versus horizontal airflow hoods are expense and ease of use. Class II hoods are more expensive than horizontal hoods and can be very costly to install due to venting requirements. Furthermore, vertical airflow hoods generally are more restrictive and may slow workflow.