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General Medical
Requirements for Thermoplastic Elastomers
Mr.
Manan
Shah,
Rubber Technologist
Thermoplastic Elastomers must meet certain medical
requirements before they can be certified for use in a
medical product. These requirements are above and beyond
the normal functional performance criteria that any
non-medical product must meet.
According to an application, a thermoplastic elastomer
might be subjected to some of medical tests as given in
below Table A.
Table A :
Typical Medical Tests for Elastomers
|
S.
NO. |
TEST |
PURPOSE |
|
1. |
Cytotoxicity |
Sensitive cell culture tests for elutables |
|
2. |
Implant
toxicity |
Cellular
response to long-term implant |
|
3. |
Biodegradation |
Loss of
functional properties and/or toxicity evaluation |
|
4. |
Flex-life in pulsatile flow |
Evaluation of long-term performance under
physiological conditions |
|
5. |
Heavy
metals analysis |
To meet
regulatory requirements |
|
6. |
Carcinogens |
No
detectable amounts allowed |
|
7. |
Tissue
compatibility |
To
eliminate pathological response |
|
8. |
Blood
compatibility |
Must not
alter blood components |
|
9. |
Ethylene
oxide residuals |
Must
meet regulatory requirements |
|
10. |
Pyrogen |
Foreign
particulates test |
Medical
Product testing must take place on the final product, as
materials might pass before processing and fail in final
product form because of processing changes.
All
thermoplastic elastomers for medical applications must be
able to withstand one or more sterilization cycles,
depending on the product and its intended applications.
Types of
sterilization along with potential problems that some
materials encounter during the respective types of
sterilization are summarized in Table B.
Table B :
Sterilization of Thermoplastic Elastomers
| S. NO. |
TYPE OF
STERILIZATION |
CONDITIONS |
POTENTIAL PROBLEMS |
| 01 |
GAMMA
IRRADIATION |
2-6
megarads |
Embitterment, radiolysis products |
| 02 |
ELECTRON
BEAM IRRADIATION |
2-8
megarads |
Embitterment, radiolysis products |
| 03 |
STEAM
AUTOCLAVE |
2500 F/30
min. |
Loss of
recovery, discoloration |
| 04 |
STEAM
AUTOCLAVE |
2700 F/15
min. |
Loss of
recovery, discoloration |
| 05 |
STEAM
AUTOCLAVE |
2850 F/5
min. |
Loss of
recovery, discoloration |
| 06 |
ETHYLENE
OXIDE |
1-3 hr |
Loss of
recovery, discoloration |
| 07 |
DRY HEAT |
|
Loss of
recovery, discoloration |
Due to stabilizer systems in these materials, problems of
discoloration, loss of recovery and embrittlement often
occurs. So, manufacturer of these materials for medical
application must address this point.
Ethylene oxide gas is currently used for sterilization,
while high-energy radiation technique is both economical
and very effective for large medical companies.
Majority of hospitals often resterilize products using
autocalve conditions that will not be tolerable for many
Thermoplastic Elastomers.
So, for disposable medical applications TPE should meet
all possible sterilization conditions.
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Mr
Manan Shah, 30, Rubber Technologist ( B.E.), has
about 10 Years’ of experience in manufacturing,
developing, testing and educating challenging
Industrial Rubber Products. He has significantly
contributed by providing custom solutions to clients
as well as detailed understanding of various
processing techniques and formulation requirements.
He also
holds a PG Diploma in Import – Export Management and
International Finance. Mr Manan Shah is a Lecturer in
Rubber technology at L.D.College of Engineering,
Ahmedabad, India.
Mr Shah
will share his vast experience with readers through a
regular column covering essential aspects regarding
medical elastomers and latex materials and products. |
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