Modern Plastics Summary: 2003
The first components made from polymers compounded with
silver are establishing a toehold in the North American and European Medical
markets. Proponents hope that these pioneering applications will prove the worth
of the materials and lead to their widespread use. However demonstrating to
potential users the real cost benefit of the expensive additives remains an
Nosocomial infections - those picked up in hospitals - are a
big problem and cost billions of dollars each year. In Germany, more people die
from catheter related infection than from traffic accidents, says Michael
Wagener, MD of antimicrobial developer Bio-Gate Bioinnovative Materials,
Organic antimicrobials like triclosan have limitations due
to temperature sensitivity and varying compatibility with different polymer
matrics that can lead to too fast or too slow an activity, explains Andrew
Barclay, technical manager of compounder Wells Plastics, England. Silver is
widely recognised as being safe and has high heat stability (over 500 degrees
centigrade) and low volatility, making it suitable for use with engineering
polymers, notes Barclay. It also provides long lasting effectiveness and wash
Wells plastics provides the Bactiglas range based on soluble
complexz glasses. A molded TPE stethoscope diaphragm cover has been on the
market for almost four years, but the bigger volume in the medical market goes
for anaesthesia systems, including extruded polypropylene and polyethylene
tubing and injection molded high impact polystyrene connectors.
commercial products generally rely on a zeolite or ceramic as a carrier for
silver. Silver ions are released by the presence of moisture or another metallic
ion, with the loading of the silver and the design of the carrier tailored to
the necessary release rate so that effectiveness lasts the life of the part.
Most of the antimicrobials are produced by firms in Japan, even if marketed by
non Japanese firms.
Asia - Pacific has led the use of silver antimicrobials,
notes Fred Gastrock, project manager at market researcher BRG Townsend. Indeed
only a few years ago, the region accounted for close to 100 % of global
consumption, which he reckoned was 5 million to 10 million ibs in 2001. Demand
has steadily been increasing in North America and Europe, with each now
accounting for about 6 to 7 % of the market, but with only limited uses so far,
Catheters Lead the Way
Doctor’s Research Group (DRG), Plymouth, CT, introduced in
2001 safeseal stethoscope diaphragm covers with AgION antimicrobial. DRG has
made over 10 million of the injection molded thermoplastic elastomer covers,
says Dwayne Poteet, vp. Of sales. It expects to produce about 5 million this
year. The warm to-the-touch covers sell for about $ 1 each and are marketed
worldwide. Many are used by promotions from the Drug companies.
While those numbers seem large, there are 16 million
stethoscope wearers in the US alones, notes Poteet. So far, response has been
greater from emergency staff than from hospital infection control specialists.
One reason, he believes, is that the latter are loathe to admit to an infection
control problem. This hinders the broader acceptance of medical goos containing
silver antimicrobials, too, say other observers.
AgIon is used at about a 5 % level. DRG suggests that the
covers be changed weekly, although the antimicrobial effectiveness is far
Edwards Lifesciences, Irvine, CA, started selling Vantex
central venous catheters with Oligon antimicrobial from Bioenvision, New York.
The extruded polyurethane catherers are sold globally and come in a variety of
sizes in2-,3- and 4-lumen configuration. The company will not reveal the level
of antimicrobial used. It compounds the PUR internally and says tested
antimicrobial is over one year in the body. The market volume of Vantex remains
guarded, but Edwards says the catheter has aroused strong interest, and sales
should grow as clinical eveidence of the effectiveness of the antimicrobial
builds. It is evaluating other applications for Oligon such as pulmonary artery
catheters which has received US FDA approval. Oligon technology involves
impregnation a polymer with silver, platinum and carbon particles. Then, when
contacted by an ionic fluid such as saline or body fluids, an electrochemical
reaction takes place, releasing silver ions.
Vygon, Ecouen, France has offered Multicath Expert Central
Venous Catheters with AgIon with 30 day plus antimicrobial protection.
Acceptance in the UK has been excellent says Alan Martin, business manager for
Vygon UK. He predicts that 70 % of all central venous catheters will contain
silver antimicrobials by 2008, driven by further clinical research demonstrating
the effectiveness of the materials. Ravi Bhatkal, AgION’s vp for strategy sees promise
for other types of catheters and in implants such as compoenets for pacemakers
and orthopedic devices. AgIon uses a zeolite carrier.
Ensinger, Nufringen, Germany, provides stock shapes
containing AgIon for applications like polyetheretherketone handles for dental
instruments, says Fran Alder, Medical market development specialist in
Washington, PA. Surgical handles and thermoformed polyphenylene sulfone
sterilization trays for surgical instruments. Tests of the trays have shown no
loss of antimicrobial efficacy after 50 autoclaving cycles. He says that such
trays will take 30% of the market in five years.
Milliken Chemicals, began offering AlphaSan, a zirconium
phosphate based ceramic ion exchange resin containing silver in Europe and US
says Geoff Haas, market manager. Unilke other products, it does not impart
color, he claims. It is now being used in products such as silicone tubing.
Ciba started marketing silver antimicrobials under the name
of Irgaguard B5000 which features a zeolite carrier and is now being used for
medical ancillaries like bed pans, says Melinda Reyes, senior marketer of new
product lines, in Tarrytown, NY. A catheter containing the material should be
marketed this year along with a base and casters for a mobile blood pressure
Clariant has introduced sanitised silver says marketing
manager Marla Brandon. It relies on a glass ceramic carrier and does not pose
color change issues she adds. Medical has not been a prime focus but hospital
flooring and mattresses are in the works and prosthetics are a possibility.
The antimicrobials are far more costly than other additives.
Clariant’s Brandon, quotes a price range of $ 40 to $ 90 per ib. Andrew
Barclay of Well’s Plastics notes
that a masterbatch generally sells for $ 30 to $ 35 per ib. Typical addition
rates of 0.25 % to 0.5 % (400:1 TO 200:1) to give a raw material on cost of
7 to 17.5 cent per ib, he says. RTP’s Marshall reckons a minimum added
cost of 75 cent per ib while Geoff Haas of Milliken places the figure at $ 1 per
Price is the issue, stresses Jody Walker, engineering
product manager at stock shapes distributor Curbell Plastics, Orchard Park, NY.
A shape with a silver antimicrobial is thre to four times the cost of one
without it, he says, adding that customers are interested in using the additive
until they see the price. Price would not be as much an issue in the medical
marekt if the value of using the materials to combat nosocomial infections were
more fully appreciated. Lack of clinical trials is a factor and so is lack of
market awareness. However, in the US for instance, producers of items using
antimicrobials can only cite their value in protecting the product, not people
who come into contact with it. The inability to claim a health benefit is a
signigicatn hindrance, many suppliers complain.
Clariant Masterbatches has recently started offereing
masterbatches containing AlphaSan and expects its first medical applications to
be commercialized in 2004 says Manfred Dicks, Winchester, VA based vp of
additive masterbatches for the Americas.
Bio-Gates Nanosilver BG uses elemental silver and comes as a
nanoporous powder containing 1- to 5- micron particles, and as 10-micron
particles nanodispersed in liquid, notes Michael Wagener who is MD. The company
is working on about 10 medical applications, including prosthetics. An
endotracheal catheter is likely to be the first commercialised.
RTP, Winona, MN has offered the materials for a long time,
says Kevin Marshall, medical market manager, but has been more actively pursuing
applications over the last two years. It is not providing material for medical
applications yet, but expects the first such products in 2004.
A. Schulmann, Akron, OH, has supplied compounds with silver
antimicrobials for several years, says Rengarajan Ramesh, vp of technology. The
firm deliberately steers clear of invasive items like catheters, but has some
medical ancillary applications in the works. For instance, a carrier tray should
be out by the end of the year.
The cost issue will diminish as the idea of reducing
infections take hold and as doctors become more convinced to use antimicrobials,
says Bio_Gate’s Wagener. It’s just a masster of times, agree’s AgION’s
Bhatkal. Five years from now, people will ask why it took so long to adopt the
antimicrobial, adds Marshall. A. Schulman’s Ramesh, for one, sees global
volume doubling or tripling in 6 or 7 years.