Bespak plc: Auto-Injectors. The Need For Forward Thinking

They may now be firmly established on the market, but auto-injectors must be further refined to cope with issues around high-viscosity formulations. Technology providers looking to develop next-generation devices are on the case.

Steven R Kaufman at Bespak Europe Ltd

As increasing numbers of injectable biologics are coming to market, the demand for auto-injectors continues to rise steadily. Most of these drugs have been offered in the 1mL long pre-filled syringe and with injection volumes generally ranging from 0.3mL up to 1.2mL. However, in recent years, there has been a clear shift towards even higher volumes and/or higher viscosities. With most auto-injectors currently using a power source that is mechanical in nature and generally spring-based, challenges are becoming more apparent.

Biopharmaceutical companies are facing fierce competition in most key therapeutic areas. One way they are seeking to differentiate is through the device. Auto-injectors, pen injectors and pump-based systems are being examined to determine which is best-suited to patient needs, can safely and effectively deliver the drug, and has the highest likelihood of contributing to compliance.

At the same time, some of the devices now offered or already on the market are not well-positioned to address the needs of the next wave of biologics and injectables. Some key concerns that have arisen are: maintaining injection times with a target time of less than 10 seconds; stalling and incomplete injections; and glass breakage.

Faster Injection Times

Injection time, in particular, is now a hot topic for discussion. A number of sources have raised concern that regulatory bodies have a preference for short injection times that do not exceed 10 seconds. With the viscous nature of some injectables, or when there are issues such as drug to siliconisation interaction, there can be problems achieving that target time – even when injecting amounts that are 1.0mL or less.

Clearly, for bolus and high-volume injections, longer injection times will be allowed. But for auto-injectors, especially those still using a 1mL pre-filled syringe, time is of the essence. How long a patient is able or willing to hold an auto-injector against their skin is a matter of debate.

To achieve a faster injection time or to overcome siliconisation problems, a simple approach has been to use a more powerful spring or to incorporate a spring with a better delivery force profile. In some cases, this can work quite effectively. In others, it can potentially lead to increased forces being applied to various components of the auto-injector that will remain under stress for years in the biopharma supply chain – and may cause breakage of the glass pre-filled syringe prior to or during the injection.

This could prevent devices from working properly, meaning patients do not get their required dose of medication. These types of scenarios could also have a serious impact on the reputation of the biopharma company involved, having a knock-on effect with both patients and regulatory authorities. Given the high value of many biologics, recalling or having to dispose of just one or two batches of these combination products could amount to tens of millions of pounds in lost revenue, with an even greater impact on the trust factor – built up with patients over time but so easily lost.

New Technologies

While spring-based auto-injectors continue to have an important role to play in the current market, new technologies – for auto-injector platforms, stoppers/valves for sequential injection and bolus injection systems – are coming on stream to address some of these concerns.

One development programme that has garnered a lot of interest is a new power source to help overcome the issues that spring-based auto-injectors can have with injectables. Based on proven valve technology, a small novel container of liquefied gas was developed as a new power source. The propellant, when released, provides sufficient energy, in the form of a pressurised vapour, to power drug delivery and other functions.

Flexible Approach

The dampened nature of this delivery mechanism prevents unnecessary impact on the primary container, which is ideal for either glass pre-filled syringes or cartridges – helping to further minimise any chance of glass breakage. This system is also flexible in that it can offer a complete spectrum of variation to adapt to the needs of the drug, therapeutic area or the patient itself. For example, by simply altering the propellant within a single container format, injection time can be customised for the most viscous injectables. In addition, by being able to provide such an effective delivery performance with the use of the same footprint, the efficiency of the space utilised allows for the design of compact devices.

As a result, changes in delivery volume and viscosity can be accepted with minimal physical changes to a device, and without having a significant impact on device development programme timelines. High viscosities and high-delivery volumes can be handled with relative ease. For instance, 2mL of a 200 cPs formulation can be delivered within about 10 seconds.

A broad range of primary containers can be used alongside the power device. Containers with a wider diameter offer no additional challenges; as such, 1mL standard, 1mL long and 2.25mL syringes can be used without any considerable effect on performance. Furthermore, the nature of the drive mechanism ensures that the primary container is completely emptied once the device has been activated.

Several variations of the devices are available for clinical trials, and a range of industrial designs is being considered for the body of the auto-injectors to best suit patient needs.

Market Edge

Auto-injectors have now become a more accepted method of delivering injectables. However, an increasing number of biotech and pharma companies are facing difficulties with high-viscosity injectable formulations – and technology advances by market players are needed to overcome some of the known problems with conventional spring-based systems. Technology that can accommodate various primary containers, as well as high-viscous and high-volume injections, offers a competitive advantage.

[About the author]

Steven R Kaufman is the Global Business Development Lead of Bespak Europe Ltd, responsible for business development activities related to injectable devices such as auto-injectors and bolus injection systems. A member of the commercial team, he works actively with the Bespak Innovation organisation in Cambridge, UK, which designs and develops advanced drug delivery devices. Steven has a biopharma background, broad experience in the drug delivery device field, and is involved with strategic alliances with related suppliers. He has extensive presentation experience and has authored several articles related to this industry. Email: steven.kaufman@bespak.com

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