Bristol, UK -- The medical plastics industry is set to expand rapidly over the next decade taking up increasing proportions of GDP, as countries provide healthcare to an ageing population, access to medicine expands in developing regions and new technology is developed, says market intelligence group AMI.
Some of the issues in using polymers in medicine were debated at the latest AMI conference on Medical Grade Polymers, 14-15 Sept 2010 in Philadelphia, Pennsylvania.
Examples of polyurethane use in medical devices include pacing and neurostimulation leads based on polyether PU developed by the Neuromodulation division of Boston Scientific. In the 1980s there were problems with the PU insulation of pacing leads caused by giant cells in the body releasing lysozyme, which in turn gives rise to free radicals, causing environmental stress cracking.
Since then, PU chemistry for implants has been improved by reducing the amount of soft domain and cutting the potential for hydrolytic cleavage. However, if a device is improperly installed leading to tensile stress, for example by using a very tight suture, then issues can still arise: a suture sleeve can protect against this occurrence.
AMI notes that Aortech Biomaterials supplies PU with polydimethyl siloxane (PDMS) soft segments, which are more biostable and have good oxidative stability. This is currently in use in over 1 million pacemakers and defibrillators, as biliary and urinary stent coatings, and in cardiac and pulmonary cannula applications. Carbonate can be introduced into the PDMS to increase polarity and give lower hardness with high tensile properties.
Another supplier of thermoplastic PU (TPU) is Lubrizol Advanced Materials, whose Isoplast grade has a flexural modulus up to 2200 000psi and very good low temperature impact properties. It can be coloured with masterbatch and is being used as metal replacement, says AMI, and also has excellent chemical resistance. It has been tested with hospital disinfectants such as bleach and glutaraldehyde, and can be sterilised using ethylene oxide, gamma and electron beam irradiation, all useful attributes for medical uses.
Impact-modified Isoplast is being used in applications such as ultrasound paddle handles and flexible joints with thin walls, notes AMI. A glass-reinforced grade has been used as metal replacement in an abdominal retractor where the number of parts was reduced from 49 to 8 and the risk of cuts from the sharp metal was eliminated, AMI adds.
AMI says the potential for polymers in the medical and pharmaceutical industries is endless, as new materials come on stream.
AMI is organising two events in 2011 to discuss new trends and offer networking opportunities. Medical Device Polymers 2011 will take place 7-9 June at the Maritim Hotel in Cologne, Germany and Medical Grade Polymers 2011 is at the Hilton City Avenue, Philadelphia from 13-14 Sept 2011.