Trinseo explains how polymers are boosting quality in drug delivery devices, enabling patients to lead an active lifestyle.
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As the healthcare market continues to evolve to meet the needs of patients, providers and our global healthcare system, self-administered therapies are growing in popularity. This is due to a number of factors: The desire to drive healthcare costs down; the emphasis on improving the quality of medical therapies, and the emphasis on treating chronic conditions at home to accommodate patients who want to self-administer treatment and continue their active lifestyles.
Drug delivery devices, also known as combination devices, provide the answer to self-administered therapies. Not only are they convenient and easy to use, they offer more precise dosage than the traditional provider-administered method, improving the efficacy of treatment.
The drug delivery devices market is segmented eg. nasal, oral, transdermal, topical and ocular. Both traditional medical devices manufacturers and pharmaceutical companies are involved in bringing the devices to market with medical device companies incorporating pharmaceuticals into portable housings, and pharmaceutical companies encasing their therapies.
A common concern of these manufacturers is being able to offer their customers – healthcare professionals and the patient – drug delivery devices that are effective therapeutically and safe, and offer functionality, convenience, haptics and aesthetics. This applies to all sorts of devices including auto injectors, insulin pens, inhalers, prefilled syringes and wearables, and is vital to ensuring patient use of the often lifesaving devices.
Polymers provide a solution
One of the key considerations in balancing therapeutic effectiveness and safety with functionality, convenience, haptics and aesthetics is the material that goes into the application. Polymers have provided an important solution to the marketplace in that they offer characteristics such as portability, durability and appealing aesthetics which can result in overall patient acceptance.
Typical materials for drug delivery devices include acrylonitrile butadiene styrene (ABS) and a polycarbonate (PC) blend; PC/ABS for housings, transparent ABS and PC for windows; polystyrene (PS) for secondary packaging; PC that can be sterilized for needle caps, and soft thermoplastic elastomers (TPEs) for comfort grips. Each one of these materials can be customised to meet the specifications of an application delivering critical properties such as:
- High impact resistance and stiffness
- Styling and appearance
- Fatigue resistance
- Chemical resistance
- Low coefficient of friction and resistance to wear
A thorough understanding is key
Ideally, polymers should be selected upfront, when an application is being designed. It is important at this stage to gain an understanding of how a device will be used. This will prevent delays in commercialising the device and provide the best chance of patient acceptance when the device is finally introduced to the market. What are the needs of the patient? What are their demographics? What are the stages of proper functionality? How will the patient prepare the device? How will he or she administer the dose? How will the device be disposed? All of these questions are important to determine the best material solution.
From an aesthetic perspective, consider a property such as colour. This can address a number of usability and acceptance issues, not only making devices more attractive but also providing important indicators of function. Colour has long been known to impact emotions. While bright, vivid colors can tend to be attractive and invigorating, cooler colors such as blue and green, have a calming effect. This is important to remember, especially when considering somewhat stressful activities as self-injection. Colour can alert a patient to proper functionality, or the correct way to administer a therapy. For example, what is the top of the device; what is the bottom? Opposing colours can provide this clue. Instructions can also be indexed with colour to ensure proper understanding. It is important to minimise error in drug administration to avoid dosage problems and risks to patient safety. Colour can be a big help in this area.
The challenge when considering colour is to create parts in their ‘true’ colours, consistently. Trinseo offers a solution with its, Magnum ABS resins, which are produced using the company’s proprietary mass polymerisation technology, rather than the usual emulsion process. This method of production results in exceptional whiteness in base resins which is ideal for colouring. It also results in superior lot-to-lot consistency, excellent processability and lower residual monomers and oligomers. Whether pure ABS is used or if it is blended with polycarbonate, the Trinseo material provides the advantages that mass polymerisation offers.
Colouring also can be a big expense. Those who have used Magnum ABS resins have experienced significant cost savings on colouring due to less pigment required, while increasing efficiency, yielding richer colours, and enabling a wider range of appearance options.
Growth in drug delivery devices
One of the fastest growing areas in drug delivery devices is self injectables. This trend began as a market in the early 1980s with applications including auto-injectors, pens and prefilled syringes.
Due to the efficacy of injectables, there are more injectable drugs in the pipeline than oral medications.
Another area to keep an eye on is wearable injectors. As patients receive at-home treatments for a longer duration, they need to rely on items such as patch devices, prefilled cartridges, controlled injections, and wearables that can be worn for infusions from five to 10 minutes.
In the future we’ll see more connectivity. Leveraging expertise from the consumer electronics industry we’ll see connectivity of drug delivery device with the healthcare provider providing the ability to monitor, evaluate and manage therapies remotely.
Breakdown of a drug delivery device
When selecting materials, it is important to analyse the various parts of a device to determine materials needed. Following is an example of a breakdown of one of the most common devices, an auto-injector pen. A materials supplier can specially engineer resins to meet application requirements, considering regulatory requirements and global harmonisation objectives, to help plan for cost-effective production. The intricacy of this particular device highlights the importance of considering the total device upfront to make sure all areas of the device are considered and parts are consolidated where possible.
A breakdown of an auto-injector pen:
Upper casing and parts
- Depending on the requirements for stiffness and aesthetics, ABS resins or ABS compounded with polycarbonate can be ideal for application areas ranging from outer housings to internal components. If colour is a consideration, mass polymerisation ABS, such as that offered in Trinseo’s Magnum ABS resins, should be considered resulting in exceptional whiteness and lot-to-lot consistency. The material can also meet the typical requirements of biocompatibility and sterilisability. Adding PC to the ABS enhances the material with physical properties of polycarbonate while maintaining the processability, toughness and flow of ABS.
Internal components
- The internal mechanics can be made from a variety of materials. Typical applications may call for polycarbonate resins that offer durability, biocompatibility, and/or transparency. Glass-filled polycarbonate resins can be used for parts requiring enhanced stiffness. Trinseo, for example, offers a glass-filled polycarbonate, its Calibre 5000 series, with glass content of up to 30% while maintaining biocompatibility. Polycarbonate resins can also feature colour compensation technology, such as Trinseo’s Calibre Megarad, for applications needing to be sterilised with gamma radiation
Lower casing including needle caps
- Similar to the upper casing, depending on the requirements for stiffness and aesthetics, an ABS resin or an ABS compounded with polycarbonate can be used for the lower casing. Polycarbonate resins with colour compensation technology, such as Calibre Megarad, can be used for needle caps requiring sterilisation as well.
Packaging
- Polystyrene resins are ideal for secondary packaging applications. If medical certification is needed to reduce risk, a general purpose polystyrene with biocompatibility, specifically for the market, might be considered. Trinseo has a polystyrene designated Styron MED polystyrene that features the stiffness and chemical resistance of general purpose polystyrene with the advantages of biocompatibility and a medically-focused notification of change of up to three years. When soft touch grips are needed for safety or comfort, a soft thermoplastic polymer can be used to enhance haptics. Earlier this year Trinseo completed the acquisition of API allowing us to offer a strong portfolio of soft-touch polymers that is complementary to its rigid performance plastics.
Summary
To create a drug delivery device that stands out, product designers and manufacturers are taking action to see to it that their products are distinctive. The material – in this case the plastic – becomes an important factor in building, protecting and projecting a brand through product quality, durability, appearance, and then differentiating with flexibility of design, colour, haptics and aesthetics.
When considering a material supplier it is important evaluate production and technical resources. It is also important to consider medical-focused policies such as security of supply, notification of change, and quality certifications such as ISO 13485 which will help to lower risk of non-compliance and increase speed to market. Since the development of drug delivery devices is generally a long road, a supplier that can be a true partner along the way is a real plus.