Brief introduction of moulded glass for injection
n Glass Type
Glass in its pure form consists of silicon dioxide with a melting point of approximately 1700°. Added network modifiers, such as sodium and potassium oxides or boric oxide are for lowering the melting point, while other network stabilizers, such as calcium and aluminum oxides are for improving the durability of the glass. Colored glass (e.g., amber glass) is produced by transition metal oxides such as iron oxides. All additives to pure silicon dioxide can be viewed as potential extractables in glass.
Glass compositions do not exist at a stoichiometric chemical composition but rather are expressed over a range of compositions. Thus, there is allowable variation within a glass type, and glass types may vary slightly among glass producers. Soda-lime-silica glass consists of silica (60%–75%), sodium and potassium oxides (12%–18%), and smaller amounts of calcium, magnesium, and aluminum oxides (5%–12%). This glass has a relatively high coefficient of expansion (COE) of 8.4-9.2 × 10?6 per degree and is susceptible to damage by thermal shock. Borosilicate glass consists of silica (70%–80%), boric oxide (7%–13%), and smaller amounts
of sodium, potassium, and aluminum oxides. The presence of boron provides greater resistance to thermal shock and to hydrolytic attack. Type I glass is available in two formulations: 3.3 glass and 5.1 glass, in reference to their individual COEs of 3.25 × 10?6 per degree and 5.1 × 10?6 per degree, respectively.
n Classification of Moulded Glass Vial for Injection
Glass containers for pharmaceutical use
Glass containers for pharmaceutical use are glass articles intended to come into direct contact with pharmaceutical preparations. The hydrolytic stability of glass containers for pharmaceutical use is expressed by the resistance to the release of soluble mineral substances into water under the prescribed conditions of contact between the inner surface of the container or glass grains and water.
The hydrolytic resistance is evaluated by titrating released alkali. According to their hydrolytic resistance, glass containers are classified as follows:
Glass Type | Hydrolytic resistance | Application |
Type I | Neutral glass, a borosilicate glass containing significant amounts of boric oxide. With a high hydrolytic resistance due to the chemical composition of the glass itself. (moulded glass vial, and tubular vial) | Suitable for most preparations whether or not for parenteral use(injection use) |
Type II | Soda-lime glass with sulfur treatment, with a high hydrolytic resistance resulting from suitable treatment of the surface of glass vial (only moulded glass vial) | Suitable for most acidic and neutral, aqueous preparations whether or not for parenteral use. |
Type III | Soda-lime glass, with only moderate hydrolytic resistance (only moulded glass vial). Some factories use amber tubing glass container for oral use. | Generally suitable for non-aqueous preparations for parenteral use, for powders for parenteral use(not including freeze-dried preparations), and for preparations not for parenteral use. |