USP (United States Pharmacopeia) has developed test methodology and specification limits for certain glass types.
Glass Types
There are four types of glass that are classified as USP glass. This glass is commonly found in Amber and Clear colors, but can also be produced in green and blue.
- USP Type I - Highly chemically resistant Borosilicate Glass; often used in pharmaceutical applications where sterilization or lack of reactivity is necessary
- USP Type II - Soda Lime glass that has been treated internally with sulfur compounds in order to mimic USP Type I Glass properties
- USP Type III - Soda Lime glass with moderate chemical resistance
- USP Type NP - General purpose Soda Lime glass that should be used when chemical durability and ability to endure thermal shock are NOT factors
USP Test Methods
The USP test methods that glass should comply with are USP <660, 661> and USP <671>.
- USP <661> - Covers testing to verify that glass meets or exceeds USP requirements for extractables and leachables
- USP <671> - Addresses performance testing of a package for pharmaceutical use
- One of the aspects covered in USP <671> is light transmission. The light transmission test can be performed on any colored container, in any material (glass or plastic). It quantifies the amount of light that can pass through the sidewall of a container (and therefore possibly affect the product contents). This test also covers moisture permeation on a bottle with a closure.
In most cases, glass meeting USP certifications also meets EP (European Pharmacopeia) standards as well. It is important to understand that not all glass manufacturers make glass that complies with USP standards. Understanding your own requirements, the Manufacturers' capabilities, and then making the right "match" is critical to long-term quality. Work with your Qorpak Packaging Consultant to ensure that you understand manufacturing capabilities and limitations.
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