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Novel premium pre-filled syringe plunger made by micro- /injection moulding for innovative drug delivery systems and auto injectors

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New plunger technology increases pre-filled syringe quality and safety

While ready-to-use pre-filled syringes for chronic illnesses, such as cancer, are growing in popularity, their manufacturing process can compromise their purity. miPLUNGER has developed a cost-effective technique that ensures both quality and safety for plungers used in these syringes.


A pre-filled syringe (PFS) is a disposable syringe already filled with a single dose of the medication a patient needs to be injected with. By avoiding the need to fill the syringe from a vial, the process is faster, easier and more accurate. PFSs are usually used for vaccines, diabetes, autoimmune diseases and cancers. Rubber plungers are typically used in PFSs and are produced following a sequence of production steps such as curing and stamping. However, while rubber does offer advantages of flexibility and strength, as a material it can contain and release impurities known as leachables and extractables. Additionally, with typical rubber plungers the gliding mechanism is often not smooth enough to ensure the avoidance of pain and discomfort when patients inject themselves. The miPLUNGER project, hosted by device manufacturer MDX, has developed a compound material and new techniques for the simplified cost-efficient sterile production of a smooth-gliding plunger. EU support enabled the team to conducted a feasibility study into how best to get the product to market.

Cost-efficient, sterile production

The miPLUNGER project has developed a two-component plunger made of fluoropolymer – the same chemical compound which gives frying pans their non-stick qualities. This material offers a number of advantages. It is highly versatile, free of any harmful leachable chemicals, while offering excellent purity and gliding properties. The plunger is manufactured by MDX in a two-step microinjection moulding process under cleanroom conditions. Production can be adapted to a variety of plunger designs. “Both the materials and the two-component moulding are used successfully in other industries where high purity is essential. With more than 20 years’ experience in these industries, it seemed obvious to combine the technologies to benefit a new application,” says Harald Grün, project coordinator. The team is currently conducting leach out and performance tests to ensure the safety and efficiency of the actual production concept of the plunger.

Reaching a growing market

The global market for PFSs is estimated at more than USD 4 billion, and, due to the increase in chronic diseases around the world, is growing annually at the rate of around 10 %. MDX will market their plunger solution to pharmaceutical and biotech companies and to PFS manufacturers. As the producers of high-value drugs and self-injection devices will be the primary users, the company will engage them early in the development process to make sure that the product meets their needs. “Our market strategy will be to push to end users to generate a pull effect from the PFS manufacturers,” explains Grün. The next phase of the project will be the development of a prototype. This device will undergo a variety of tests to explore issues such as safety, by investigating extractables and leach out (release of toxins during the process), performance and the long-term stability of the materials and mechanism.


miPLUNGER, syringe, microinjection, moulding, extractables, leach, fluoropolymer, sterile, plunger, rubber, vial, vaccines

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