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Award-winning device for self-injection of an arthritis medication meets stringent requirements for reliability and ease of use.

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The SimpleJect™ auto-injector system is designed for self-administration of Amgen Inc.’s Kineret™ (anakinra) drug for rheumatoid arthritis. The injector’s manufacturer, Owen Mumford Ltd., Woodstock, England, worked closely with Amgen in developing it.

SimpleJect™ has earned the Arthritis Foundation’s Ease of Use commendation and has received two prestigious awards this year. Canon Communications gave it a Medical Design Excellence Award in June, and the Healthcare Compliance Packaging Council presented it with its Compliance Package of the Year Award in May 2002.

Steven Rolfe, industrial designer and phase project leader for Owen Mumford, said, "Because SimpleJect™ is so easy and safe to use, it promotes self-reliance and compliance among arthritis sufferers who need to administer their own injections on a daily basis. The guesswork is taken out of self-injection, in that SimpleJect™ sets the correct penetration level every time."

The device is also designed to assuage the fears of needle-phobic patients, according to Owen Mumford. The colorful and robust design does not resemble in any way a classic syringe; patients never see the needle of the syringe, before or during the injection.

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Application Description

SimpleJect™ consists of a carrying case and two main assemblies, a handle containing an actuating mechanism and a housing assembly that holds the syringe during injection. To use it, the patient places a syringe in the housing, cocks the actuating mechanism, screws the handle into the housing, places the end of the housing on the injection site and pushes down on the handle to inject the drug.

Materials Selected and Why

The syringe housing and a needle shroud assembled to one end of it are injection molded from a special low-friction nylon resin, DuPont™ Zytel® 7335F. The same resin is also used for the body of the actuating mechanism located in the handle assembly. Low friction is very helpful for this part when the patient screws it into the syringe housing made of the same resin.

In addition to meeting low-friction requirements, Zytel® 7335F also fulfills requirements for mechanical strength and the right balance of stiffness and toughness. Its mechanical strength enables the parts to withstand repeated injection forces.

Devices were thoroughly tested by Owen Mumford, including extended life cycle and resistance to extreme heat (+70°C at 90 percent humidity) and cold (-40°C). In drop tests, they also performed faultlessly with a 100 percent pass rate and no damage to the syringe or to the SimpleJect™.

Another part of the syringe housing, the syringe carrier, is molded from a standard acetal grade, Delrin® 500. It is snap-assembled inside the housing, snapping perfectly into place and remaining firmly in place for thousands of injections. In addition to its eminent suitability for snap-fit assembly, Delrin® was selected for its strength, impact resistance and dimensional stability, all key factors in long-term delivery accuracy.

Owen Mumford and DuPont worked closely together to select materials for optimal performance of SimpleJect™. DuPont specialists also assisted Owen Mumford with full mold flow analyses and help in rapid prototyping and production tool design.

Amgen senior packaging engineer Jean-Michel Guirado, based in the company’s European logistics center in The Netherlands, said: "The use of DuPont engineering polymers means that SimpleJect™ has an attractive and ergonomic, robust design that is easy to use, even for severely disabled patients with impaired dexterity. This was proven when we received a message of thanks from a blind RA sufferer in the United States whose life has been made infinitely easier since SimpleJect™ has been made available for her daily Kineret™ injections."


Founded in 1952 and headquartered in Woodstock, England, Owen Mumford is well-known throughout the world as an innovative manufacturer of small medical devices. Employing over 350 people on two manufacturing sites in the U.K., the company specializes in manual and automated high-volume assembly, needle cannulae grinding, the injection molding of plastic components and the insert molding of blood lancets. For more information, visit

Amgen is a global biotechnology company that discovers, develops, manufactures and markets important human therapeutics based on advances in cellular and molecular biology. More information is available at .