A conventional syringe has a built-in gap. The barrel is open at one end so the plunger can move in and out, and Boris Zubry, founder of Avicenna, argued in a 2010 paper that this one opening explains many of the syringe's oldest problems. His proposed fix is a syringe with no plunger at all, and so no opening: a sealed cartridge moved by magnets.
Zubry starts from the three things that decide how long a drug lasts: light, temperature and air. Light is handled with additives and tinted packaging, temperature with cold storage, and air with vacuum or a nitrogen purge. But a syringe still works by drawing and pressing a plunger, however well it is made, so the opening stays. In his view it lets air, impurities and bacteria creep in, and a drug can spoil before its stability runs out even if it has been stored properly.
The result, he says, is a choice between two imperfect options. A drug in a vial or ampoule can keep for a very long time until the container is opened, but it needs a separate syringe. A prefilled or cartridge syringe is more convenient, yet its shelf life is usually under a year, limited by the quality of the fill and the seal between piston and barrel wall.
The shorter the shelf life, the more medication expires and has to be destroyed, and Zubry asks how much that adds to the cost of healthcare. Ordering, shipping and storing syringes, vials and ampoules adds more, and the end user ends up paying. He also raises the environment. Vapors from leftover medication, he says, can escape through the opening in used syringes and build up inside disposal containers, which are designed to guard against sharps rather than fumes. And ordinary syringes struggle to handle gases at all.
The system he describes is the Magnetic Plungerless Injection System, covered by US Patent 7,255,684. A single-dose cartridge is fully sealed, with a solid back wall, and filled under vacuum or nitrogen. Inside sits a ferrous piston. Outside the cartridge wall, a magnet in a hand-held injector pulls the piston along, because a magnetic field passes through glass and plastic. Move the piston one way and the drug is pushed out through a sterile needle. Move it the other way and the device draws material in, so the same design can inject or extract. It can hold liquids, powders and gases.
In ideal conditions, Zubry estimates, shelf life would be limited only by the drug's own stability, which he puts at years and possibly decades.
Manufacturers come first. Drugs are made in batches sized by sales, shelf life and equipment, and cleaning and paperwork between batches can take longer than the run itself. Zubry's example is four hours of production to make a month's supply of one drug, followed by a whole shift of cleaning. With a long enough shelf life, he says, twelve batches (a year of sales) could run in a week, with a single clean afterward. Vacuum is the obvious route to longer life, but it doesn't work with today's formats. Ampoules are heat-sealed, a multi-dose vial loses its vacuum on first use, and in a prefilled syringe it can suck the plunger in and break the seal. A plungerless cartridge avoids all three.
Providers could buy in larger quantities and store only cartridges, with no separate syringes to order. Zubry says a cartridge weighs about half as much as a syringe, so disposal would cost about half as much, and that the plunger accounts for half the waste of a disposable syringe. Shipping gets simpler too. Prefilled syringes travel in specialized containers, he says, and vibration can damage the seal at the plunger opening, which pushes some companies to fill locally and accept short, costly runs.
Patients could do more of their injections at home, since sealed cartridges could be sent by mail. Zubry adds that the cartridges could also be used to collect samples after a chemical or biological incident.
Zubry wrote that the system was still in development and invited ideas on how to move it forward. Avicenna, which he founded, is now developing a magnetically driven, plungerless cartridge platform with a reusable injector. Everything above is Zubry's own projection.
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