Types of glass

Glass is an inorganic material that is produced by melting silicon dioxide with additives such as soda, lime and aluminum oxide. Its special properties make it ideal for pharmaceutical applications:

1. Chemical inertness

Glass does not react with most pharmaceutical products, minimizing the risk of interaction or contamination.

2. Transparency

Glass is translucent, allowing easy visual inspection of contents to detect contamination or color changes.

3. Barrier properties

Glass is impermeable to moisture, oxygen and other gases, which ensures the stability of the medicine.

4. Thermal resistance

Glass can withstand high temperatures and is suitable for sterilization processes such as autoclaving.

5. Recyclability

Glass is an environmentally friendly material that can be recycled without loss of quality.

The pharmaceutical standards of the United States Pharmacopeia (USP) and the European Pharmacopoeia (EP) divide glass into three main types:

1. Type I: Borosilicate glass

- This glass contains boron oxide and is extremely resistant to chemicals and temperatures.

- It is used for sensitive pharmaceuticals, injectables and biological products.

2. Type II: Treated soda-lime glass

- The surface is chemically treated to increase resistance to aqueous solutions.

- Often used for acidic or neutral aqueous solutions.

3. Type III: Soda-lime glass

- This standard glass is suitable for solid dosage forms such as tablets or capsules, but not for liquid or parenteral products.

1. Ampoules

- Small glass containers for single-dose injections.

- They are usually made of type I borosilicate glass and are opened by breaking.

2. Vials

- These glass containers can hold single or multi-dose solutions.

- Type I or type II glass is used depending on the type of product.

3. Glass bottles

- Glass bottles are used for oral liquids such as syrups or suspensions.

- They are made of type II or type III glass.

4. Cartridges and prefilled syringes

- Special glass containers for dosing systems such as insulin pens.

- They are made of type I glass to ensure sterility and compatibility.

5. Dropper bottles and tubular glass

- These are often used for ophthalmic and nasal preparations where precise dosages are required.

1. Chemical resistance

Glass prevents chemical substances from being exchanged between the container and the medicine, which preserves the stability of the product.

2. Suitability for sterilization

Glass can withstand high temperatures and sterilization processes, which is particularly important for sterile products.

3. Transparency

Allows visual control of the quality of the product.

4. Recycling and sustainability

Glass is fully recyclable, making it a sustainable packaging solution.

1. Fragility

Glass is sensitive to mechanical shocks and can break if handled incorrectly.

2. Cost

The production and treatment of high-quality pharmaceutical glass, especially type I, is expensive.

3. Weight

Glass containers are heavier than plastic alternatives, which can increase transportation costs.

4. Leaching

Under extreme storage conditions, alkali ions can leach from the glass into the product.

Glass containers are subject to strict regulatory requirements defined by pharmacopoeial standards such as the USP, EP and JP. The most important tests include:

1. Hydrolytic resistance

- This test measures the amount of alkali released when glass comes into contact with water.

2. Thermal shock tests

- Glass containers are tested to ensure that they can withstand rapid temperature changes without breaking.

3. Particle tests

- Visual inspections are carried out to ensure that containers are free from contamination or defects.

4. Chemical resistance tests

- These test how well the glass can withstand aggressive chemicals.

1. Lightweight glass

New manufacturing processes reduce the weight of glass without compromising stability.

2. Coated glass

Special coatings improve resistance to leaching and increase breakage resistance.

3. Intelligent packaging

New technologies integrate sensors to monitor the storage conditions of pharmaceuticals.

4. Optimization for biologics

Biopharmaceutical products place higher demands on glass containers, e.g. for highly viscous drugs or cold storage.

Glass containers are an indispensable part of the pharmaceutical industry as they keep medicines safe, stable and effective. Despite some challenges such as fragility and cost, glass remains the preferred choice for packaging sensitive products. With new innovations and improved technology, the role of glass in pharmaceuticals will continue to be crucial.