How to determine the Protective Properties of Amber Glass Containers?

Colored glass containers are usually used to contain light-sensitive drug products. A previously issued USP Stimuli Article on the measurement of the protective properties of colored glass containers has now been republished in Pharmacopeial Forum (PF) 49(4). The article provides proposed maximum allowed specific transmission values for colored glass containers. The comment deadline is 30 September 2023.


According to the article, the purpose of the proposal is to replace the current approach that determines spectral transmission requirements based on container volume with one that is based on wall thickness. The amount of light that passes through the glass wall depends on the glass composition, the annealing time and temperature, and the wall thickness. "As the market does not use standardized containers, a correlation between the filling volume and the wall thickness cannot be made reliably", the authors of the article state. Thus, it is proposed to correlate spectral transmission to the wall thickness of the glass containers rather than the filling volume. 

Proposed Maximum Allowed Specific Transmission Values for Colored Glass Containers

A lot of data were obtained for ampules, bottles, and vials. However, only a few data were obtained from examples of syringes and none for cartridges. Data for low boron content borosilicate glass vials was obtained from China where it is still widely used.

The Stimuli Article contains a table providing the maximum allowed specific transmission values for colored tubular glass containers based on the nominal wall thickness. For molded glass containers, the maximum allowed transmission should be 10%, regardless of the wall thickness.

For comparison: The previous stimuli article proposed minimum allowed absorbance values.

More information is available in the Stimuli Article "The Measurement of the Protective Properties of Amber Glass Containers" after registration to the Pharmacopeial Forum.

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