Glass as a packaging material

By – Maniz, Sushana, Sandip, Ishwor and Shrijana.

Packaging

In the pharmaceutical industry, it is vital that the package selected adequately preserve the integrity of the product.

The selection of package therefore begins with a determination of the product’s physical and chemical characteristics, it’s protective needs, and it’s marketing requirements.

Packaging materials in pharmaceutical industry are: Glass, Metal, Plastic, Paper and Rubber.

The materials selected must have following characteristics:

a) They must protect the content from environmental condition.

b) They must not be reactive to the productc) They must not impart to the taste or odor of

product.d) They must be non toxic.e) They must be FDA approved.f) They must meet applicable tamper resistance

requirements.g) They must be adaptable to commonly employed

high speed packaging material.

Protective functions of packs Environmental protection : Temperature,

moisture and humidity, light, gases and volatile materials

Mechanical protection : compression, impact, vibration

Biological hazards : Microbiological, other infestation, Humans

Introduction Glass is composed principally of sand, soda

ash, limestone and cullet. The sand is almost pure silica, the soda ash is

sodium carbonate, and the limestone, calcium carbonate.

Cullet is a broken glass that is mixed with the batch and acts as a fusion agent for the entire mixture.

The composition of glass varies and is usually adjusted for specific purposes.

The most common cations found in pharmaceutical glassware are sodium, calcium, magnesium, zinc and potassium.

Colored glass

Glass containers for drugs are generally available in clean flint or amber color.

The amber coloration results from the addition of iron oxide to the glass.

For decorative purposes, special colors such as blue, emerald green and red may be obtained from the glass manufacturer.

Colored glasses are effective in protecting the content from the effect of sunlight by screening them.

Types of glasses Type I : Borosilicate glass Type II : Treated soda lime glass Type III : Regular soda lime glass Type IV : NP- general purpose soda lime glass

Type I : Borosilicate glass

It is least reactive. A substantial amount of alkali or earth cations are

replaced by boric oxide. This type of glass has higher ingredient like aluminium

and zinc and higher processing costs and is therefore used primarily for more sensitive pharmaceuticals such as parenteral or blood products eg. Ampoules and vials.

Type II : Treated soda lime glass

When a glass is stored for several months in damp atmosphere or with extreme temperature variations, the wetting of surface results in slats being dissolved out of glass in the form of fine crystals. This is called ‘BLOOMING OR WEATHERING’. At this stage these salts can be washed off with water or acid.

Commercial soda lime glass is dealkalized or treated to remove surface alkali to prevent the weathering of empty bottles. This treatment is known as ‘SULPHUR TREATMENT’.

SULPHUR TREATMENT involves treating the glass surface with sulfur dioxide or ammonium sulfate.

It also has a high chemical resistance but not as much as type I.

It is cheaper than type I glass, however, and is acceptable for most products and aqueous pharmaceuticals with a pH greater than 7.

Type III : Regular soda lime glass

Types III and Type IV glass have similar compositions and distinguished from each other by their hydrolytic resistance.

Containers are untreated and made of commercial soda-lime glass of average or better than average chemical resistance.

Suitable for non aqueous parenterals and non parenteral products.

Type IV : NP- general purpose soda lime glass These have lowest hydrolytic resistance,

which can sometimes be seen as a surface bloom if the glass is stored in damp conditions for prolonged periods, and is suitable for solid products, some liquids and semi-solids, but not for parenterals.

Advantages Versatile and attractive. Can be moulded into many shapes, sizes and

colours of container. It is hygienic and suitable for sterilization, it

has excellent barrier properties, it is relatively non reactive, it can accept a variety of closures, and glass containers can be used on high speed packaging.

It can be colored to protect light sensitive materials.

It can be reused.

Disadvantage

It is fragile. It is heavy. Hence, difficulty in transport. It is harder to dispose. It is expensive.

Referencea) The theory and practice of industrial

pharmacy by Leon Lachmannb) Aulton’s Biopharmaceutics