Plastics in the medical technology sector: Polycarbonate adsorber housings

Robust in everyday hospital use, suitable for hot-steam sterilization

Thursday - October 5, 2006 - Leverkusen – Therapeutic apheresis is an innovative treatment process that enables substances which cause disease to be safely removed from the blood while it is outside the body. The Bad Homburg, Germany-based medical technology company Fresenius Medical Care has developed a new technology called DALI® (Direct Adsorption of LIpoproteins) especially for the treatment of patients with severe lipometabolic disorders. Among other things, it enables LDL cholesterol, also known as “bad cholesterol” because of its influence on vascular calcification, to be extracted from the blood. The main component of the technology is an adsorber filled with a special material that, for example, electrostatically bonds the LDL cholesterol. For the housing of the adsorber system, a fracture-resistant plastic was required. “In the end, the first choice was our Makrolon® 2458,” explains Markus Krieter, expert in medical technology in the Polycarbonates Business Unit of Bayer MaterialScience AG. “The polycarbonate is sufficiently tough and stiff, which protects it from becoming easily damaged in the often hectic everyday hospital environment. Our material also readily withstands the pressurized hot-steam sterilization of the DALI® adsorber, where temperatures reach at least 121 °C for over 20 minutes.”

A further benefit of the polycarbonate is its high transparency which allows continuous visual monitoring of the blood treatment by hospital personnel and therefore enhances patient safety. Makrolon® 2458 meets the requirements of the American standard US-Pharmacopeia, Class VI, relating to the biological compatibility of plastics. Like all medical technology products from Bayer MaterialScience, it also complies with international standard ISO 10993-1 regarding the biocompatibility of plastics that are in contact with body fluids and tissue for up to 30 days.

In the DALI® treatment, the patient’s blood is removed from an arm vein and passed through the adsorber where the LDL cholesterol sticks to the adsorber globules. The cleaned blood reenters the patient’s body via another arm vein. More than 160,000 patients have been treated with DALI® since its introduction.

Constancy of formulation and long-term availability of the products
Bayer MaterialScience secures the majority of its business with well-known medical technology manufacturers through exclusive development cooperations. “It is very important to us to be viewed as a reliable partner. We therefore safeguard the long-term availability of our medical technology materials, ensure reliable delivery and provide binding assurances that the formulations for these substances will remain constant,” explains Krieter. In addition to its cooperations, Bayer MaterialScience also monitors changes to standards in the medical technology sector and independently tests the materials affected to ensure compliance with the extended requirements.

The company provides a comprehensive service to support manufacturers of medical instruments and associated plastics processors. “We help at every stage of the process, from the initial idea and design of a plastic component to mold construction and production launch,” says Krieter. For instance, CAE tools are available for analyzing the thermal expansion and static and dynamic properties of a component. The service package also includes thermogravimetric measurements and screening experiments for contact media durability and rheological calculations e.g. to relocate inconvenient weld lines or optimize mold filling behavior.

With sales of EUR 10.7 billion in 2005, Bayer MaterialScience AG is one of the world’s largest polymer manufacturers. Its main fields of activity are the production of high-tech polymer materials and the development of innovative solutions for products used in many areas of everyday life. The main consumer sectors are the automotive, electrical/electronics, construction, sports and leisure industries. Bayer MaterialScience has production facilities at 40 sites around the world and a workforce of approx. 18,800. Bayer MaterialScience is part of the Bayer Group.


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Andrea Huber

Trade and Technical Press

Bayer MaterialScience AG

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