Specific Gravity test standard for topical cream and gel



I am trying to find the Specific Gravity test standard for topical cream and gel.

Does anyone know if any test standards or pharmacopeial may apply?

Thank you very much in advance.


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A basic search on the "web" using "Microsoft Copilot found this:
  1. Description: This test involves a qualitative description of the drug product, including its appearance and packaging. Manufacturers specify the acceptable appearance of the finished dosage form.
  2. Identification: Identification tests establish the identity of the drug(s) present in the article. These tests help differentiate between compounds with closely related structures.
  3. Assay (Strength): A specific and stability-indicating test determines the strength (content) of the drug product. Manufacturers use a variety of analytical procedures to achieve overall specificity.
  4. Other Quality Attributes: Additional tests cover impurities, physicochemical properties, uniformity of dosage units, water content, pH, apparent viscosity, microbial limits, antimicrobial preservative content, antioxidant content, sterility (if applicable), and other product-specific attributes.
In summary, while specific gravity isn’t part of the standard tests, these other assessments ensure the quality and performance of topical medications."

I did not find any references to a specific gravity test. Why do you need that?



Hi, Jason,

Our products subject to specific gravity are cosmetics.

On the drug side, specific gravity has always been an important part of characterisation of a topical or transdermal delivery system. USP General Chapters: <841> is SPECIFIC GRAVITY for liquids. There are other FDA guidances on specific gravity requirements for topical drugs.

On the other hand, ASTM has several test methods on specific gravity for petroleum, types of commercial pastes but not specifically for topical cream and gel for human use. I have not looked into military standards yet.

It is a very simple test to characterise the mixture. You can use a "gourmet" apparatus or pycnometer, for a cheaper instrument solution but longer man-hour or a high-end density meter, expansive but happier lab technician. Either will be suitable for cosmetic GMP once it is calibrated.

However, I am interested in whether there is a STANDARD out there or we are just following the scientific principles to get the specific gravity results traceability to national or international standards.
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