Writer： admin Time：2022-06-08 10:28 Browse：℃
Glass containers are among the primary packaging material that has found use in the pharmaceutical industries. A large number of pharmaceutical formulations have been packaged using glass containers glass containers and they are usually the first choice of packaging materials. Glass is an inorganic material (mostly silicates) or mixture of materials which when heated up and then cooled, solidifies without crystallization.
Composition of glass
Glass is principally made up of silica (59-80%) with varying degree of calcium oxide (5-12 %) sodium oxide (12-17 %) aluminium oxide (0.5-3.0 %), barium oxide, boric oxide, potassium oxide, and magnesium oxide. The high melting point of glass is due to the presence of silica. The melting point and melt viscosity of the glass is modified by the addition of oxides.
Classification of Glass
Glass containers are classified into Type I glass, Type II glass, Type III glass and Type IV glass based on their degree of chemical/hydrolytic resistance to water attack. The degree of attack is dependent on the degree of alkaline release under the influence of the attacking media.
i. Type I glass containers (Borosilicate glass / Neutral glass)
This is a type of glass container that contains 80% silica, 10% boric oxide, small amount of sodium oxide and aluminium oxide. It is chemically inert and possess high hydrolytic resistant due to the presence of boric oxide. It has the lowest coefficient of expansion and so has high thermal shock properties.
Uses of Type I glass containers
Type I glass is suitable as packaging material for most preparations whether parenteral or non-parenteral.
They can also be used to contain strong acids and alkalis
ii. Type II glass containers (soda-lime-silica glass/ treated soda-lime glass/ De alkalized soda lime glass)
This is a modified type of Type III glass container with a high hydrolytic resistance resulting from suitable treatment of the inner surface of a type III glass with sulfur. This is done to remove leachable oxides and thus prevents blooming/weathering from bottles. Type II glass has lower melting point when compared to Type I glass and so easier to mould.
Uses of Type II glass containers
They are suitable for most acidic and neutral aqueous preparations whether parenteral or non-parenteral.
iii. Type III glass containers (Regular soda lime glass)
This is an untreated soda lime glass with average chemical resistance. It contains 75% silica, 15% sodium oxide, 10% calcium oxide, small amounts of aluminium oxide, magnesium oxide, and potassium oxide. Aluminium oxide impacts chemical durability while magnesium oxide reduces the temperature required during moulding.
Uses of Type III glass containers
They are used as packaging material for parenteral products or powders for parenteral use ONLY WHERE there is suitable stability test data indicating that Type III glass is satisfactory.
They used in packaging non-aqueous preparations and powders for parenteral use with the exception of freeze-dried preparations
It is also used in packaging non-parenteral preparations.
Type IV glass containers (Type NP glass/General-purpose soda lime glass)
This type of glass container has low hydrolytic resistance. This type of glass containers are not used for products that need to be autoclaved as it will increase erosion reaction rate of the glass container.
Uses of type IV glass containers
It is used to store topical products and oral dosage forms
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