Why COP Bottles Do Not Change Color After Irradiation Sterilization

 Irradiation sterilization is a critical step in pharmaceutical, medical, and food packaging industries to ensure that products are free from harmful microorganisms. While materials like glass and some plastics can change in appearance or degrade after exposure to radiation, Cyclo Olefin Polymer (COP) bottles remain remarkably stable. This stability makes COP an ideal material for sensitive applications. In this blog, we will explore why COP vials do not change color after irradiation sterilization and why they are preferred for sterile packaging solutions.

after Irradiation Sterilization

What is Irradiation Sterilization?

Irradiation sterilization uses ionizing radiation—such as gamma rays, electron beams, or X-rays—to kill bacteria, viruses, and fungi. This method is particularly effective because it penetrates deep into materials without the need for high temperatures, making it suitable for heat-sensitive products.

However, ionizing radiation can affect some materials by altering their molecular structure. For instance, certain plastics may discolor, become brittle, or lose mechanical strength. These changes can compromise product appearance and integrity, posing risks in applications that require high material performance and transparency.

What is COP?

Cyclo Olefin Polymer (COP) is a high-performance thermoplastic known for several desirable properties:

RTU(ready to use) 2ml COP vial

Optical clarity: Similar to glass, making it suitable for transparent containers.

High chemical resistance: Compatible with sensitive substances, including pharmaceuticals.

Dimensional stability: Resists deformation under varying temperatures and conditions.

Low extractables: Reduces the risk of contamination, making it ideal for medical and biological storage.

COP has become the material of choice for injectable drug containers, pre-filled syringes, diagnostic kits, and laboratory equipment, where sterility and product integrity are critical.

Why Do COP Vials Resist Color Change After Irradiation?

Stable Molecular Structure

COP is engineered with a highly stable carbon backbone. Unlike some polymers, it lacks certain chemical groups—such as aromatic rings or carbonyl groups—that are prone to reacting with radiation energy. As a result, irradiation does not trigger molecular breakdown or rearrangement that would cause discoloration.

100ml polymer vial

Resistance to Oxidation

Oxidation reactions are one of the main culprits behind color changes in irradiated materials. COP’s structure is resistant to oxidation, meaning fewer byproducts form that could affect color or transparency.

Minimal Crosslinking or Chain Scission

In many polymers, irradiation causes crosslinking (linking of molecular chains) or chain scission (breaking of chains), which can alter the material's appearance and performance. COP exhibits minimal crosslinking under radiation exposure, preserving its clarity and physical properties.

Low Additive Content

Some plastics contain additives, like dyes, stabilizers, or plasticizers, which may degrade under radiation and cause discoloration. COP typically has low or no additives, ensuring that it remains stable during sterilization.

Application of HDPE container with desiccant cap in dry syrup

In the pharmaceutical industry, dry syrup is a popular oral dosage form for children and elderly patients due to its high bioavailability and good drug stability. However, the effectiveness of dry syrup depends largely on its storage conditions, especially moisture-proof measures. This article will explore the important application of pharmaceutical HDPE desiccant bottles in the storage of dry syrup and its impact on drug stability.

50ml desiccant bottle with CRC

Characteristics and advantages of dry syrup

Dry syrup is usually in powder form and needs to be mixed with water before taking, which is convenient for patients to take. Compared with traditional tablets and capsules, dry syrup can disintegrate outside the mouth and quickly form a uniform suspension, thereby improving bioavailability. This makes dry syrup the preferred dosage form for many drugs, especially those for pediatric patients.

Storage Challenge: The Importance of Moisture-proof

The storage conditions of dry syrup directly affect its effectiveness. Due to the special nature of its ingredients, once affected by moisture, it may cause the drug to deteriorate, decompose or become ineffective. Therefore, moisture-proof measures are key to ensuring the stability and efficacy of dry syrup.

desiccant bottle with silica gel

Design and materials of pharmaceutical HDPE container with desiccant cap

Pharmaceutical moisture-proof bottles are usually made of polyethylene or polypropylene materials, which have good barrier properties and can effectively isolate external moisture and impurities to protect the drug ingredients in the bottle. In addition, the design of moisture-proof bottles usually takes into account sealing performance to ensure a dry internal environment.

To further enhance the moisture-proof effect, desiccants are generally placed in pharmaceutical moisture-proof bottles, and desiccants are usually placed on the top of the lid. These desiccants can effectively absorb the residual moisture in the bottle to ensure that the dry syrup remains stable throughout the storage period. By maintaining low humidity, desiccants help prevent physical and chemical deterioration of drugs, thereby ensuring that the efficacy is not affected.

Pharmaceutical moisture-proof bottles play a vital role in the application of dry syrups. By selecting the right materials and designs, and combining them with effective desiccants, these desiccant bottles provide a stable storage environment for dry syrups, ensuring the long-term effectiveness and safety of drugs.

DMF Grade HDPE Bottles

 In industries like pharmaceuticals, healthcare, and nutraceuticals, maintaining product integrity is non-negotiable. One critical factor in this process is the choice of packaging. DMF grade HDPE bottles have become a preferred packaging solution for many companies because of their superior quality, regulatory compliance, and reliability. 

HDPE bottle with child resistant closure

What Is a Drug Master File (DMF)?

A DMF is a confidential submission to the FDA (U.S. Food and Drug Administration) containing detailed information about a material, component, or process used in the manufacturing of drug products. It provides supporting documentation to assist companies and regulatory bodies in evaluating the safety and quality of these components.

What Is a Type III DMF?

Type III DMFs focus specifically on packaging materials used in pharmaceutical products. These packaging components ensure that the drug product remains stable, uncontaminated, and effective throughout its shelf life. This type of DMF applies to a wide variety of packaging items used in pharmaceutical applications, including bottles, caps, seals, and other protective materials.

Examples of Packaging Materials Covered Under Type III DMFs

HDPE (High-Density Polyethylene) Bottles

Used for tablets, capsules, and liquid formulations.

FDA-compliant, non-leaching, moisture-resistant material.

Often paired with desiccant caps for moisture-sensitive products.

HDPE containers with desiccant cap

Closures and Caps

Child-resistant caps for safety.

Tamper-evident seals to ensure integrity and prevent contamination.

Flexible Films and Foils

 

28mm child resistant cap 

DMF Grade HDPE (High-Density Polyethylene) bottles are bottles manufactured according to the stringent standards outlined in these submissions. They are widely used in pharmaceuticals, biotech, and medical packaging to ensure compliance with regulatory norms.

Key Features of DMF Grade HDPE Bottles

1.Manufactured with US DMF-approved raw materials to meet the highest regulatory standards.

2.Produced in a cGMP compliance to ensure product purity and safety.

3.100% quality inspection using advanced, highly calibrated inspection systems.

4.All pharmaceutical plastic packaging complies with updated USP <661>& <671> standards for material safety and performance.

5.High-capacity production guarantees on-time delivery and supply consistency.

6.Packaging is designed with uniform wall thickness, minimal taper, and concavity to allow for smooth, wrinkle-free labeling, ensuring a professional presentation.