Page 20 - Laboratory manual for students FAR222 2019 20

FAR 222 Dosage Form II Laboratory Manual

complete the pharmaceutical production document and related document e.g. label before
practical class.

General preparation of sterile products in the laboratory is summarised below:

i. Preparation (measurement) of ingredients needed
The amount (volume) of the preparation is usually 3 to 4 times the volume to be dispensed
due to the loss in the filtration and transferring process. The incompatibilities of ingredients
must be checked before preparation. Taring a container may be needed.

ii. Dissolution of solid ingredients in the vehicle

The solubility of solid ingredients must be checked to ensure they solubilise in the given
volume of formulation. It is recommended to dissolve solid ingredients separately or one after
another. Liquid ingredients may be used to help in dissolution of solid ingredients to avoid
exceeding the final volume of formulation. Mild heating of the vehicle may help in dissolving
poorly soluble ingredients such as boric acid.

iii. Dilution of very small quantities solid ingredients

The minimum weighable quantity (MWQ) of electronic balance in the School’s Compounding
Laboratory is 200 mg. Any ingredients with a weight below this MWQ needs to be prepared
using dilution method. The volume of vehicle needed to prepare the stock solution must be
adequate to dissolve the ingredient (check the solubility of the ingredient). At the same time,
it must not affect (usually exceeding) the total volume of formulation.

iv. Mixing of all ingredients

Mixing of ingredients should only be done in beakers but not in calibrated equipment.

v. Topping up with the vehicle

It is very important to use calibrated equipment such as measuring cylinder, conical measure
etc to measure the volume needed for liquid ingredients or to top up the final volume of
formulation. Beakers are not calibrated equipment and shall not be used for measuring an
exact volume of liquid.

vi. Filtration and clarity assessment

Once formulation is prepared, it should be filtered using an appropriate choice of filter e.g.
sintered glass filter grade 3 (15 – 40 µm) repetitively until it is clear (free from particles) upon
checking under liquid inspection viewer or Allen liquid viewer.

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