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Kraton aims to replace NR and synthetic
rubbers with new IR for medical uses
Since its commercialisation five years
ago, Cariflex polyisoprene rubber has
been finding its way into numerous
medical applications as a substitute
for natural and synthetic rubbers.
Recent testing has shown the material
to have significant advantages,
according to Kraton executives.
By Louise McHenry, ERJ staff [email protected]
Engineered polymers producer Kraton
Performance Polymers first commercialised
its Cariflex synthetic polyisoprene (IR) five years
ago, offering it as a replacement for other rubbers
on the medical market, including butyl, and other
isoprene rubbers, such as natural rubber.
Natural rubber used in extended contact with
skin or bodily fluids has been plagued with
problems – either real or perceived – relating to
allergic reactions.
In a paper at the International Rubber Expo
held in Ohio in October, Kraton presented the
results of third party testing on medical stoppers
made using different types of rubber including
Cariflex. The testing shows that Cariflex polymers
are good choice for the medical stopper market,
Richard Brennan, VP Cariflex polyisoprene
products, and Dr Philippe Henderson, global
industry manager, told ERJ in a 30 Oct telephone
interview.
Medical stoppers
vary in complexity,
Brennan told ERJ.
“Each application has
a unique design and
different
requirements,” he
said, giving the
example of the
intravenous (IV) bag
market. Some very
simple designs, such
as IV bags containing ‘Unique design’
saline or glucose,
Richard Brennan
require a stopper that
prevents the fluids from leaking out. Others, like
multi-chamber IV bags that require drugs to
blend, can be “very sophisticated” in design,
Brennan noted. This requires very specific custom
engineering, “which allows us to demonstrate to
customers the different skills
that we have.”
Henderson pointed out three key properties
that medical stoppers need: good coring
resistance, resealability and a low level of
extractable impurities. In its testing Kraton
compared Cariflex anionic IR with butyl rubber
(including chloro- and bromo-butyl types) and
NOVEMBER/DECEMBER 2012
Ziegler-Natta IR, a polyisoprene made using a
titanium-aluminium catalyst. Natural rubber was
not used in the test, as it has been phased out of
the stopper market.
In terms of coring resistance, Cariflex
performs “significantly better” than Ziegler-Natta
and butyl, Henderson noted, meaning that when
a needle is inserted into the stopper, there are no
fragments contaminating the drug. (see figure 1)
Resealability is important so there is no risk of
leakage as modern drugs, such as
chemotherapy drugs, while aggressive and
efficient in their treatment of cancers, can have a
“toxic effect on the caregiver,” if they were to
come into contact with the doctor or nurse’s skin,
Brennan noted.
There are two ways to test this, quantitatively
and qualitatively. The former – a measurement of
how often leakage occurs – shows that all tested
rubbers give roughly the same results. The
occurrence of leakage is low, though when it
happens it is a serious issue, Henderson said.
However, when a qualitative test is carried out,
the results are more obvious and Cariflex scored
well here.
Henderson added that Cariflex is shown to
have a low level of extractable impurities, that is
to say the likelihood of elements of contamination
from the material in the drug is low. He noted that
butyl is also good here, but claims that “it leaks
small amounts of impurities over a long period of
time, due to ageing.” Henderson also noted that
interaction between the drug and the stopper is
very important, and the inertia of the material
means that it is more likely to be compatible.
Opportunities in
skin contact markets
Kraton’s Cariflex IR material is also used in other
medical applications such as surgical gloves,
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where it serves as a replacement for natural
rubber. Though NR latex gloves have the largest
share of the market globally, synthetic gloves are
proving popular due to their anti-allergenic
properties, Brennan commented, claiming that
the material provides a good balance of
protection and comfort that may not be present
in other synthetic rubbers, such as nitrile, which
has the lion's share of the synthetic glove market.
The Houston, Texas-headquartered
company’s share of the surgical glove market is
growing very strongly, though with regional
differences. In the US, the company has about 25
percent of the market, while in Europe, it is “much
smaller” though “more than niche,” Brennan said,
noting that this has partly to do with the litigation
environment in the US where healthcare
professionals are more wary of malpractice suits
that could arise from allergic reactions.
The BRIC countries – Brazil, Russia, India and
China – are following closely behind, as the
Figure 1: Result of the coring test showing resistance
plus resealability. Cariflex is at top followed by zn
and butyl rubbers. (Images from Kraton).
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M E D I C A L
“emerging middle-class” becomes more aware of
allergy problems and seeks an alternative. There
is also potential in other Asian countries, such as
Malaysia and Thailand – traditional homes of NR
– but these are still very small, Brennan noted.
Brennan noted that there is potential in the
skin contact markets for Cariflex. Condoms is a
“fast growing market” though it is more niche
than gloves. Others include catheters and
probe covers, for applications such as
ultrasound imaging.
In terms of testing for these markets,
Brennan noted that Kraton’s customers have to
go through rigorous testing before devices are
approved for use on the human body. This varies
by region though there are a lot of similarities in
terms of testing. “I think generally there is a
common platform in terms of purity and good
manufacturing but there is some difference
between the US, Europe and Japan,” the big
regulatory market systems, Brennan said.
Huge potential in medical
Cariflex is one of the faster growing materials in
Kraton’s portfolio, the company said. As of 30
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“The medical industry is a large market
with a regulatary framework plus there
is strong substitution from NR to
synthetic materials.”
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June 2012, it represented 7 percent of the
company’s overall turnover of €106 million and
the “adoption rate is good.” This is because the
markets that Kraton is targeting are “large
markets with a regulatory framework and there
is a strong substitution dynamic away from NR
to synthetic materials,” Brennan explained.
Brennan noted that the product had a
“long incubation period” and that work began
some ten years ago. Commercialisation began
five years ago but it has expenenced a “new
life” in terms of brand and market focus in the
last few years.
Kraton supplies the specialist production
plants in Brazil and Japan with solid IR from its
main manufacturing base in Belpre, Ohio. “We
have no plans to bring [Cariflex isoprene rubber
latexproduction] to the US. Brazil is a great
location for South America, and Japan is only
ten days delivery away from anywhere in
Southeast Asia,” he explained. “We have
invested $50 million in this business over the
past three years and have demonstrated to the
medical industry that we are a committed
I
supplier,” Brennan concluded.
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