Page 14 - Quality control of pharmaceuticals (07-PA 704) practical

B) Sterility test can be carried out by using one of the following two method:

1. Membrane Filtration Sterility Testing

Membrane filtration sterility testing is the regulatory method of choice for filterable
pharmaceutical products, as cited in the USP <71>. Samples are passed through a 0.45 µm
membrane filter in a filtration canister and culture medium is added for incubation. This method
of sterility testing can provide increased sensitivity in comparison to other methods as the whole
sample, or a composite sample is passed through a single filter. Filtration also provides an
opportunity to rinse away components in the sample that may cause turbidity or inhibit growth,
such as antibiotics or preservatives.

Apparatus

The sterility test apparatus consists of a closed reservoir and a container to collect the filtrate,
between which a property supported membrane of appropriate porosity is placed. Membrane
generally suitable for sterility testing has nominal porosity of 0.45 micrometer, diameter about
50 mm, flow rate 55-75 ml of water. minute at a pressure of 70 mm of mercury. Cellulose nitrate
membranes are used for aqueous, oily, and weakly alcoholic solutions and cellulose acetate
filters for strongly alcoholic soln. complete unit should be free from microganism including the
membrane, and operation should be carried out aseptically. Preferably assemble and sterilize the
entire with the membrane in place prior to use.

2. DIRECT INOCULATION

In direct inoculation, a small volume of sample is removed aseptically from the sample unit and
inoculated directly into a suitable volume of growth medium before incubation. While simple,
this method of testing can have some significant limitations. Only small volumes of product can
be inoculated into the culture medium, limiting the test sensitivity. If the sample appears cloudy
or turbid after inoculation, it can be challenging to detect turbidity from microbial growth at the
end of the incubation period. Additionally, if the product has antimicrobial properties, the sample
must be neutralized so that microbial growth is not inhibited.

C) Procedure for sterility Testing by Membrane Filtration Method

1. Set up the Millipore filtration system under LFH.
2. Remove the outer covering of aluminum foil in the hatch and then transfer the

apparatus under LFH with the inner covering.
3. Before the start of the test remove the inner covering of aluminum foil and set the assembly

to make it ready for filtration process.
4. Centre a sterile membrane filter, aseptically, using a fine sterile flat tipped forceps on each of

the filter holder to be used and clamp the funnel tight.

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