Sterile preparation Facilities and Equipment

Laminar Airflow HoodBiological Safety Cabinet

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.

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.

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.

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).

How They Work?

oLaminar 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.

oAir is taken through a filtration system and then exhausted across the

work surface as part of the laminar flows process.

oCommonly, the filtration system comprises of a pre-filter and a HEPA

filter.

oThe Laminar Flow Cabinet is enclosed on the sides and constant

positive air pressure is maintained to prevent the intrusion of

contaminated room air.

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.

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.

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.

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:-

1. Air flow is vertical, flowing down on the work space. This airflow pattern

protects the operator against potential hazards from the products being

prepared .

2. 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.

Laminar Airflow Hood Basics

A laminar flow hood has three basic functions.

1.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.

2.Second, the constant flow of air out of the laminar flow hood prevents

room air from entering the work area.

3.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.

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.

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.

Both the console and bench models are available with vertical rather

than horizontal airflow.

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:

1.70% of isopropyl alcohol (or another appropriate disinfecting agent)

should be used to clean all interior working surfaces before each use.

2.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.

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.

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

Biological Safety Cabinets

oSince 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.

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.

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.

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.

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.

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.