A breakthrough in vinyl research has created an exciting new opportunity for manufacturers of medical devices.

Scientists at the German PVC resin manufacturer Vestolit GmbH & Co KG have succeeded in incorporating a bioactive molecule directly into the polymer backbone, one that duplicates the function of the natural blood component heparin by preventing the formation of clots. Teknor Apex will use the resins resulting from this research to develop a new series of compounds for devices that process living blood during critical medical procedures.

An agreement signed by Teknor Apex and Vestolit grants Teknor Apex exclusive worldwide rights to develop and produce these innovative compounds. Teknor Apex expects to have the products ready for commercialisation in about two years.
The tendency of blood to clot or coagulate when it contacts foreign objects poses a problem in procedures like open-heart surgery, dialysis, platelet collection, wound drainage, and insertion of catheters into arteries and veins. In tubing, catheters, extracorporeal circuits, and other medical devices, the new compounds from Teknor Apex will provide substantial cost-performance advantages over the anti-clotting (anti-thrombogenic) coatings currently applied to the inner surfaces of such devices, according to Bertram M. Lederer, senior vice president of Teknor Apex.

“By increasing the reliability of devices that process blood during critical medical procedures, the compounds based on Vestolit’s new resins will benefit the healthcare industry and even have the potential to save lives,” Lederer says.
Unlike standard anti-thrombogenic coatings, the bioactive components in Vestolit resins are permanently affixed to the PVC backbone and are non-extractable, according to Peter M Galland, industry manager for Teknor Apex.

“While compounds based on these specialised copolymers will cost more than standard medical-grade vinyl, device manufacturers can minimise costs by co-extruding the compounds onto standard vinyl in thin layers. As a result of limiting the bio-active compound to a thin inner layer and allowing the bulk of the wall of the device to consist of conventional medical PVC, the overall material cost will rise by less than the added cost of current coating methods.”

Under the agreement with Vestolit, Teknor Apex has acquired worldwide rights to use the new PVC resins in vinyl compounds and to market them as Teknor Apex products, according to Lederer.

“This exclusivity includes access by Teknor Apex to supplies of the resin and to technical data concerning it. The agreement provides for continuing technology interchange between the two companies to further this process.”

The work will yield important benefits for healthcare professionals responsible for medical procedures where clotting is a major concern.
“When blood leaves the body during open-heart surgery or kidney dialysis,” says Galland, “the blood’s inherent coagulation cascade mechanism is called into play. Through a series of sophisticated interactions, the components of our blood stream begin to recognise that they are having an out-of-body experience, so to speak, and begin a process that results in clotting.”

In the past this problem has been dealt with by the introduction of such substances as heparin to the blood itself, and by application of heparin or heparin-like coatings to the device surfaces.
“The effect of heparinising the blood is to make the patient, who has just undergone a critical procedure, become a bleeder capable of unstoppable hemorrhaging at the wound site,” Galland says.
“On the other hand, coatings are expensive, non-permanent, and hence capable of being extracted by the blood.”
By coextruding the new Teknor Apex compounds in a thin layer over standard medical-grade vinyl, a manufacturer of medical tubing could reduce costs  “by an order of magnitude” in comparison with coating, according to Galland.