Glass containers for pharmaceutical use are intended to come into direct contact with pharmaceutical products. Glass used for pharmaceutical containers is either borosilicate (neutral) glass or soda-lime-silica glass. Borosilicate glass contains significant amounts of boric oxide, aluminum oxide and alkali and/or alkaline earth oxides. Glass is also classified as Type I, II or III based on intended use. These general chapters, USP <660> Containers – Glass and EP (3.2.1) Glass Containers for Pharmaceutical Use deal with the Glass Grains Test and the Surface Glass Test. The Glass Grains Test, combined with the Surface Glass Test for hydrolytic resistance, determines the type of glass being used in the packaging of pharmaceutical preparations.
 

Type I

Borosilicate Glass

This type of glass has borosilicate structure. It is ideal for containing all injectable preparations with acid, neutral and alkaline pH. It has good resistance to thermal shocks and can be sterilized before or after filling. Container of USP type I glass (Neutral borosilicate glass)

Type II

Soda-Lime-Silica Glass but with a suitable treatment on the inner surface to increase the hydrolytic resistance

This type of glass is a soda-lime glass which, by means of a special treatment, reaches the hydrolytic stability of type I glass on its surface layer of 0.1-0.2 um. It is suitable for acidic and neutral parenteral preparations. Type II glass container can be sterilized before or after filling. Container of USP type II glass (Treated soda-lime glass)

Type III

Soda-Lime-Silica Glass

This type of glass has average hydrolytic resistance. It is suitable for containing non-aqueous injectable preparations and those in powder form. It can also be used for non-parenteral preparations. Type III glass container should be sterilized by dry heat before filling. Container of USP type III glass (Soda-lime glass)