Types of glass

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Types of glass: Glass of the following types are available commercially for making containers.

Types of glass for making containers

  1. Lime-soda glass: It is composed of SiO2 (75%), Na2O (15%), and CaO (10%) along with traces of K2O, MgO, and Al2O3. Lime-soda glass can be manufactured easily. Further, it is not so expensive. It is used for preparing containers that are meant for the storage of solid medicaments. It is however not suitable as a container material for storage of parenteral products because:
    • It liberates alkali in aqueous preparation. On repeated use, its surface loses some of its brilliance. It is not resistant to sudden changes in temperature.
    • Flakes separate more easily as compared to other types of glass.
  2. Borosilicate glass: It is composed of SiO2 (80%), B2O3 (12%), Al2O3 (6%), and a mixture of Na2O, CaO, and other oxides (2%). It is chemically more inert than lime-soda glass. It is highly resistant glass.
  3. Silicone-treated glass: Glass is treated with silicone so that can be used for preparing containers to store alkali-sensitive products.
  4. Sulphured glass: It is a cheaper variety of glass used for the construction of containers for parenteral products. The soda-lime glass is exposed to moist SO2, at about 500°C to get the sulfured glass. It does not liberate alkali.
  5. Neutral glass: It is composed of SiO2 (72-75%), B2O3 (7-10%), Al2O3 (4-6%), Na2O (6-8%), BaO (2-4%) and K2O (0.5-2%). It is used for the preparation of multidose vials, transfusion bottles, and ampoules.
  6. Amber colour glass: Amber colour glass container is used for storage of photosensitive pharmaceutical products because it has the capacity to filter out UV radiations. Containers for injectibles preparations must be made from uncolored glass.

The following two types of glass are used for the preparation of containers meant for storage of parenteral preparations.

Types 1 glass (Borosilicate glass or Neutral glass): It offers a high degree of hydrolytic resistance due to the chemical composition of the glass.

Types 2 glass (Soda-lime suitably de-alkalized): It has a high degree of hydrolytic resistance as a result of appropriate surface treatment.

Advantages, Disadvantages of glass, different types of glasses for making of container

Advantages

  1. They are available in various sizes and shapes.
  2. They are economically available.
  3. They are easy to clean, strong, and rigid.
  4. They are chemically inert.
  5. They are neutral after proper treatment.
  6. Can protect photosensitive drugs from light.
  7. They are transparent and easy to label.

Disadvantages

  1. These containers may release alkali to a group preparation.
  2. Glass containers are increases the cost of transportation.
  3. Glass containers are fragile and easily broken if dropped.

Also read: Pharmaceutical packaging material and types

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