The United States Pharmacopeia (USP) classifies glass containers based on their chemical durability to ensure they meet the necessary safety and quality standards for pharmaceutical use. This classification is crucial for determining the suitability of glass containers for different types of pharmaceutical preparations, based on their potential interaction with the glass. The USP categorizes glass into the following types:

1. Type I: Borosilicate Glass
   – Characteristics: Made from silica and boron trioxide, Type I glass is known for its excellent chemical resistance and minimal interaction with its contents. It has a high resistance to temperature changes and is considered the most inert type of glass.
   – Applications: Ideal for storing products that are sensitive to pH changes or contain strong acids or alkalis. Commonly used for parenteral (injectable) drug packaging, including vials, ampoules, and syringes.

   

2. Type II: Treated Soda-Lime Glass
   Characteristics: This is soda-lime glass that has been treated to improve its chemical resistance, typically by treating the surface with sulfur to reduce alkali leaching.
   Applications: Suitable for packaging acidic and neutral aqueous products not intended for parenteral use. This includes some oral and topical pharmaceuticals.
3. Type III: Soda-Lime Glass
   Characteristics: Made from silica, soda ash, and lime, Type III glass offers good chemical resistance but is more reactive than Type I glass. It has not undergone surface treatment like Type II glass.
   Applications: Generally used for non-parenteral products such as oral and topical medications. It is suitable for products that do not interact aggressively with the glass.

   
   
   

4. Type NP: General-Purpose Soda-Lime Glass
   Characteristics: Also a soda-lime glass, Type NP (Non-Parenteral) is not classified based on chemical durability like the other types. It is considered the least resistant to chemical attack.
   Applications: Intended for dry products or products that are not sensitive to slight interactions with the glass container. At the same time, it is also the type of food storage & cosmetics container used by most on the market.
   
   Each type of glass has been developed to meet specific needs, balancing factors such as cost, durability, chemical resistance, and the physical demands of the product it is intended to contain.