In the pharmaceutical packaging industry, pharmaceutical aluminum foil plays a vital role due to its excellent barrier properties. It is widely used in the packaging of solid dosage forms such as tablets, capsules, and powders. It effectively blocks light, water vapor, oxygen, and microorganisms, thereby protecting the stability and shelf life of pharmaceuticals.
In practical applications, pharmaceutical aluminum foil is primarily divided into two categories: thermoformed and cold-formed. These differ significantly in production processes, performance characteristics, and application scope.
The Importance of Pharmaceutical Aluminum Foil
Pharmaceutical packaging demands extremely high standards: it must block water vapor, oxygen, and light to prevent degradation; it must also be convenient to carry and use; and it must meet the high-speed automated production needs of pharmaceutical companies. Globally, the majority of solid dosage form packaging utilizes aluminum-based composite films, particularly thermoformed and cold-formed aluminum foil. It offers the following features:
High barrier properties: It almost completely blocks gas and light, ensuring drug stability;
Physical protection: It is strong and formable, protecting tablets from external forces;
Lightweight and environmentally friendly: Aluminum is lightweight and recyclable, meeting green development requirements;
Processability: It can be easily printed with text and images, enhancing brand image and providing anti-counterfeiting capabilities.
Thermoforming Pharmaceutical Aluminum Foil
Thermoforming, also known as PTP (Press Through Pack) foil, softens PVC, PVDC, or PP plastic film by heating. It is then pressed using a mold and pressure to form tablet pockets, which are then covered with aluminum foil to create a sealed blister pack.
PTP aluminum foil generally consists of a protective layer, a printed layer, an aluminum foil backing, and a heat-sealing layer. It requires moderate strength and ductility, with a focus on heat-sealing performance with the plastic backing.
Thermoformed foil is commonly used for packaging tablets, capsules, and common oral solid dosage forms, such as vitamin tablets, painkillers, and cold medications.
Advantages
Lower cost : compared with cold forming, the process is more mature and cost-effective.
High production efficiency : fast sealing speed, suitable for large-scale, high-speed automated production.
Transparency : the plastic blister base is usually transparent, allowing consumers to see and count tablets directly.
Disadvantages
Limited barrier properties of plastic substrates, relatively weaker moisture resistance.
Unsuitable for drugs highly sensitive to humidity and light.
Typical shelf life of 1-2 years, shorter than cold forming foil.
Cold Forming Pharmaceutical Aluminum Foil
Cold-formed pharmaceutical aluminum foil, also known as Alu-Alu packaging, is typically constructed from a three-layer laminate of nylon (OPA), aluminum (Alu), and PVC. These three layers work in tandem: nylon provides strength and formability; aluminum foil offers superior barrier properties; and PVC provides inner support and heat-sealing properties.
Cold-formed aluminum foil relies solely on mold pressure to form the aluminum-plastic composite film into a drug channel, without the need for heat. The aluminum foil can be stretched and deformed at room temperature, ultimately forming a three-dimensional drug channel structure that is then sealed with a sealing layer.
As a result, cold-stamped aluminum foil is widely used for high-value-added pharmaceuticals and those that are extremely sensitive to moisture and light, such as hormonal drugs, antibiotics, anticancer drugs, and cardiovascular medications.
Advantages
Superior barrier properties : nearly complete protection against water vapor, oxygen, and light.
Ideal for sensitive drugs : ensures stability of moisture- and light-sensitive medicines.
Extended shelf life : up to 3-5 years or longer.
High safety : aluminum shielding effectively isolates drugs from environmental influence.
Disadvantages
Higher cost and slower processing speed than thermoforming.
Non-transparent packaging, making it impossible for consumers to visually inspect drugs.
Slightly heavier, leading to increased transportation costs.
Thermoforming vs. Cold Forming: A Comparison
| Dimension | Thermoforming Pharmaceutical Foil (PTP) | Cold Forming Pharmaceutical Foil (Alu-Alu) |
| Process principle | Plastic film heated and softened, then molded and sealed with aluminum | Aluminum-plastic laminate directly molded under pressure |
| Transparency | Transparent, allows visual inspection of drugs | Completely opaque, no direct identification |
| Barrier performance | Moderate, depends on plastic film properties | Excellent, nearly complete barrier to gas, moisture, and light |
| Water vapor barrier (WVTR) | Usually > 0.1 g/m²/day | Usually < 0.01 g/m²/day |
| Cost | Lower, suitable for mass-market drugs | Higher, suited for high-value medicines |
| Shelf life | Around 1-2 years | 3-5 years or longer |
| Applications | Common tablets, capsules | Light-sensitive, moisture-sensitive, expensive drugs |
| Ease of use | Easy, foil is easily punctured for access | Less convenient, requires more force to peel |
| Appearance | Glossy, clear blister | Matte silver blister |
Conclusion
Thermoforming (PTP foil) is an economic and efficient solution, suitable for the majority of conventional medicines where barrier requirements are not extremely strict.
Cold forming (Alu-Alu foil) provides the highest level of protection, making it the ideal choice for sensitive and high-value pharmaceuticals.
When selecting pharmaceutical foil, manufacturers must carefully consider drug properties, packaging costs, production efficiency, and required shelf life to make the most appropriate decision.