Methods of Analysis: 3. Biological methods: 3.2 Test for sterility: 3.2.1 Test for sterility of non-injectable preparations
The methods are described under 3.2 Test for sterility.
Certain dosage forms such as ophthalmic drops, ophthalmic ointments, topical semi-solid dosage forms to be applied to damaged skin, etc., require specific sampling plans and preparation of samples.
For the membrane filtration method and for direct inoculation of the medium, determine the number of containers according to the sampling method proposed. The quantity taken should be not less than the minimum and not more than the maximum quantity given below. The quantity used for each medium, which should be taken from the mixed sample, is also specified in the table.
Sampling plan
Type of preparation |
Total pooled for each medium |
Quantity to be used |
Membrane filtration method |
||
Aqueous solution |
10 - 100ml |
5 - 10ml |
Preparations soluble in water, isopropyl myristate, or other solvents |
1 - 10g |
equivalent to 0.5 - 1g |
Direct inoculation method |
||
Liquid preparations |
10 - 100ml |
5 - 10ml |
Soluble preparations |
1 - 10g |
equivalent to 0.5 - 1g |
Insoluble preparations to be suspended or emulsified, e.g. creams and ointments |
1 - 10g |
equivalent to 0.5 - 1g |
If the membrane filtration method is used for ointments and creams, the preparation being tested may require additional heating up to 40 °C (or exceptionally up to 45 °C with continuous stirring). The filtration process should be carried out as quickly as possible. If heat is applied and/or a solvent combination is used in the sample preparation, the method should first be validated to ensure that the specific expected bioburden is not affected by these conditions.
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