Cyclic olefin copolymers make strong inroads in pharmaceutical packaging.

Traditional pharmaceutical packaging materials have been refined over decades to provide a high degree of protection for sensitive goods. However, with technological advancement, new packaging challenges have arisen which are better solved with the use of a new generation of materials.

One of the newer materials finding favor in the packaging of modern pharmaceuticals is the family of cyclic olefin polymers and copolymers. These ultra-pure, high-clarity products deliver a new level of safety and purity, which is ideally suited for the increasingly complex and sensitive active pharmaceutical ingredients (APIs) entering commercial use today.

Wide Range of Industry Offerings with Distinct Performance

In healthcare applications, cyclic olefin-based polymers and copolymers (COPs and COCs, respectively) are available from several manufacturers. These cyclic olefin materials share similar monomeric building blocks, and although each is made via a unique process, the resulting materials are similar in many ways.

All cyclic olefin plastics share backbones composed only of carbon and hydrogen, and thus are intrinsically very inert and non-reactive. Extractable and leachable profiles of this class of materials are typically excellent. Optical properties of cyclic olefin resins are as close to glass as those of any known plastic. Almost all are very rigid thermoplastics which can be injection-molded or extruded to produce packaging items.

Selection of specific cyclic olefin materials is often based on heat resistance, processing and property parameters, and cost. In all cases, cyclic olefins are significantly less prone to breakage than glass in container applications, while weighing much less and enabling greater design flexibility.

Sterilization is of critical importance to pharmaceutical packaging, and cyclic olefin materials are compatible with many leading sterilization techniques. In general, COCs and COPs are not impacted by ethylene oxide. All makers offer grades that can withstand the temperatures of steam sterilization (at least 121°C/250°F and in some cases higher). Some grades also tolerate radiation sterilization techniques, such as gamma or beta processes. It is important to confirm specific technique compatibility with the resin supplier.

Cyclic olefin resins have been extensively tested for regulatory compliance in pharmaceutical applications with excellent results. Many grades are compliant with U.S. and EU Pharmacopoeia, while suppliers have established drug and device master files with the FDA. As with sterilization compatibility, regulatory compliance for specific grades should always be reviewed with the supplier.

Syringes, Vials, and Wearables: Targeted Applications

Among the leading applications for cyclic olefins is pre-filled syringes. The high purity of these resins and the close dimensional tolerances they deliver are often superior to glass-based alternatives, resulting in longer shelf life and more consistent performance. The high moisture barrier of these polymers also contributes to excellent shelf life and formulation stability. The physical stability of some APIs in silicone-lubricated glass syringes can be a vexing problem, but silicones can be avoided in cyclic olefin systems. Many suppliers offer cyclic olefin syringes today. Some syringe makers explicitly cite their resin source, while others have coined a brand of their own to delineate their cyclic olefin line.

Another similar application is vials and bottles for drug storage. The exceptional clarity of cyclic olefin resins results in a container that visually resembles glass, but is lighter and less likely to shatter. Inertness, low extractables and leachables, and strong moisture barrier all serve to protect APIs from loss of potency to a greater degree than plastics, such as PP and PC, can hope to achieve. For situations where the API also requires protection from oxygen ingress, leading industry suppliers have developed multilayer plastic bottles and vials that combine the purity of cyclic olefin plastics with an oxygen barrier resin layer for a powerful protective combination.

Of particular interest in the healthcare field is the recent development of wearable drug delivery devices for chronic conditions. A leading example is insulin delivery systems. Wearable devices require low profile and light weight, along with high precision and ruggedness. Cyclic olefin resins are a perfect fit for these devices, with several commercial examples today and a multitude of developmental applications in the pre-commercial pipeline.

Packaging Films

Not all the action is in rigid containers, however. Flexible and rigid packaging films can also benefit from the unique attributes of cyclic olefin resins. The amorphous nature of these polymers puts them in the same class as well-known thermoforming materials such as PVC and PETG, with similar performance in blister forming equipment. And there is a growing market for pharma companies seeking the combination of crystal clear appearance, good blister forming, and halogen-free moisture barrier provided by cyclic olefins.

These materials also offer film manufacturers the opportunity to make a complete multilayer barrier blister film in a single pass via coextrusion, avoiding the lamination and coating processes required with older barrier technologies. Solid oral dose packaging with COC- or COP-based blister films has achieved regulatory compliance and commercial success in major global markets, with new applications constantly emerging. These films also deliver an extra level of performance in the packaging of functional devices, particularly those of a large enough size that traditional barrier materials such as PVDC and PCTFE fail to retain their barrier performance at the depth of thermoforming required to package the device.

Cyclic olefin materials are also used in flexible packaging as sealant layer components in the packaging of pharmaceutical ingredients that tend to readily adsorb and permeate through more common sealant resins. A prime example is pouch packaging of nicotine-containing products such as patches. The low adsorption of many pharmaceutical compounds by cyclic olefins enables potency to be maintained, while enabling conventional heat sealing for maximum product protection. This has become an especially acute need with the impending market withdrawal of sealant films made from polyacrylonitrile (PAN) resin.

Many healthcare-related items are packaged in flexible, thermoformed plastic packages for shipping and handling. These plastic films need to be durable without adding excess weight and cost. Polyethylene (PE) is an inexpensive solution, but it is not a high-performance material. When PE is enhanced with cyclic olefin resins, stiffness and thermoforming performance are improved in these applications. Cyclic olefin/PE films can compare favorably in both cost and performance to packages made with nylon or ionomer resins, as well as PE-only films.

Other significant and growing healthcare-related applications for cyclic olefin materials include high-performance consumables such as microfluidic devices for analytical and diagnostic testing; mold components for contact lens manufacturing; and various components of medical devices ranging from optical scanners to bone cement mixers used in joint replacement procedures.

The unique properties of cyclic olefin resins have enabled development of a broad range of pharmaceutical packaging applications. As performance and regulatory demands on packaging grow ever more difficult in the coming years, cyclic olefin-based products will continue to increase their share of this important market.

About Timothy Kneale

Trained as a chemical engineer, Timothy Kneale has held a variety of plastics industry product development and technical leadership roles. During the last 10 years, he has served as President of TOPAS Advanced Polymers and overseen sales and market development activities in North America. For more information, visit www.topas.com.

This article can also be found in the April 2016 edition. 

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