Injectors typically comprise of a glass syringe, an injection mechanism for the delivery of a drug and, potentially a needle safety mechanism for the safe disposal of the device. Design Engineer, Will, discusses the advantages and disadvantages of both.

Most Primary Drug Containers (PDC) are made from borosilicate glass, a material that’s been used for over 100 years. However, some PDC’s are made from polymers as changing the material and manufacturing process can have multiple additional benefits over glass PDC’s.

As many device manufactures are focusing their efforts on making their devices more sustainable, just how sustainable are polymer based PDC’s?

Variable dose injector pens are particularly challenging as characterisation of the PDC needs to be fully understood prior to significant development of the device’s mechanism. Furthermore, variability of the drug being dosed through small PDC geometry can result in potentially dangerous scenarios of under or, overdosing the user.

Below, we have listed the advantages and disadvantages of glass and polymer PDC’s.

 

glass-syringe

Glass Syringes Advantages:

  • Proven history of drug compatibility
  • Regulatory Acceptance
  • Market familiarity
  • Glass’s barrier properties prevent oxygen and water vapour from interacting with drug compounds
  • Established manufacturing and filling processes
  • 100% recyclable
  • Coloured glass can provide protection from UV rays under some more challenging environmental requirements
  • Highly temperature resistant
  • Ability to be collected, sterilised and reuse

Glass Syringes Disadvantages:

  • Lubricants risk contamination
  • Tungsten contamination from glass
  • Plunger stiction leading to delivery inconsistency, which can result in wet injections
  • Risk of glass breakage
  • Formulation viscosity and volume limitations
  • Large manufacturing tolerances
  • Complex supply chains reliant on specialist suppliers
  • High energy requirements for manufacture
  • Fragile during transit

Polymer PDC Advantages:

  • Delivery speed consistency, preventing wet injections even when injecting challenging formulations, e.g. non-Newtonian fluids
  • Shorter injection times for viscous formulations, without the risk of glass breakage
  • Needle depth consistency, reducing the risk of adverse events
  • Improved user experience through smaller gauge needles
  • Design freedom & flexibility of moulding techniques allow for certain features to be incorporated into the design, such as; rotational alignment, increased strength from rib structures, semi-compliant structures, dedicated viewing windows for clarity, dual drug systems, etc
  • Tighter tolerances can be achieved
  • Potential for smaller device design
  • Potential for reduced device weight

Polymer PDC Disadvantages:

  • Not 100% recyclable
  • Waste management plan recommendations and challenges associated
  • Material compatibility of new polymers with drug solution, container and stopper

The development of sustainable medical devices is clearly a complicated process, and sometimes it requires the application of specific sustainable strategies in order to just become more sustainable, rather than totally environmentally friendly. Recalls of devices are not only extremely costly but can take considerable resource and may damage company reputation and are also extremely polluting in the energy required to actually recall the devices from the market.

The transportation of product to user is typically the most polluting factor in most LCA’s. Ensuring that a device is only transported once, and is as minimal and lightweight as possible can also significantly reduce the environmental impact of a device. Risk assessment of medical device development upholds efficacy and safety. If polymer PDCs can be designed for your system, it may actually be more effective, safer and more sustainable (in certain aspects) than typical glass PDC’s.

Exploration and evaluation of the wider picture, enables the right solution to be identified. If you would like to learn more or discuss a project, please get in touch.

William Morris - Senior Design Development Engineer & Business Development Manager at Haughton Design Will Morris 20 January 2022

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Get in Touch with Will Morris

Senior Design Development Engineer & Business Development Manager

Will graduated from the University of Wolverhampton with a degree in Product Design. Prior to Haughton Design, Will worked for Renishaw, where he led the industrial design for the current and next generation metal Additive Manufacturing machines. Will has a strong interest in Design for Sustainability, and the Circular Economy, looking to reduce companies’ environmental impact and often teaches about design engineering at local STEM events. Outside of work, Will enjoys Formula 1, rugby and travelling with friends.

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