Progress Report, Standards for Biomedical Devices
Barbara Kanegsberg, Ed Kanegsberg, July 2004
Contamination control in biomedical devices impacts soils regardless of status
of viability.1-3 There is an ASTM working group and associated standard under
development for overall assessment of extractable residue. The test method
is geared toward metallic components to be used in implantable biomedical devices.
We have been following the development of this standard4 and periodically provide
progress reports. Development of the standard is of interest to biomedical
device manufacturers and to the FDA. In addition, the emergence of this standard
has potential profound, positive implications for all who are concerned with
critical applications, where contamination control is a must.
The standard will be applicable to implantable metallic components with
a range of soils, materials of construction, and product configuration.
The standard
under development would detect extractable contaminants using general gravimetric
methods. Given the diversity of materials and soils, proposals for extraction
methods include ultrasonics and refluxing with either water or any of an
array of organic solvents.
The goal of the working group is to develop a standard, not a guidance
document. This is significant in that, once the standard is finalized,
companies can
refer to it as a fairly specific part of their process. At the same time,
it is likely that details of the extraction process will have to be documented
for the specific product of concern. For example, it appears that given
the diversity of contaminants and of product configurations, it would
be unrealistic
to specify or even to recommend one or two extraction solvents. In addition,
given the diversity of safety and environmental regulations as well as
specific company policies which restrict or even ban particular solvents,
specifying
a universally-acceptable solvent is daunting, and probably unachievable.
Sampling
techniques is another important issue. The challenge is to specify sampling
in such a manner that product diversity and variable lot size (including
small production runs) are accounted for.
The intent of the current work is relatively narrow; for example, the
draft standard is not intended to cover re-usable biomedical devices.
However,
the current approach would be general enough, that applicability could
range beyond
that of the medical device community. By analogy, at one time, military
specifications had power far beyond the military world. There are estimates
that mil-specs
were used by some 50% of businesses.5 The medical device standard, once
developed and tested, has the potential for similar, if not greater broad-scale
applicability.
The draft standard is obviously a work in progress. Depending on the
extent of comments received, it is conceivable that the standard could
be in place
in the Fall of 2004. At that point, round-robin testing would begin.
Therefore, along with developing the new standard, the working group
is also considering details of a round-robin testing. This will be
a challenge.
Obviously,
not all conceivable parameters can be tested, so representative soils,
substrates, and configurations will have to be selected. Pinning
down the details of
the ultrasonic process will also be a challenge. While ultrasonics
are often considered
in a rather generic sense, such factors as frequency, amplitude,
tank design, solvent, time, and temperature can profoundly impact
extraction
efficiency.
In addition, ultrasonics metrics is still in a developmental stage.6-8
The round-robin testing is therefore expected to yield results and
findings which
will also be valuable to the overall manufacturing community.
We live in a world inundated by standards. An effective standard,
in our opinion, should be achieved by consensus and should be pertinent,
achievable,
practical,
and adaptable to a range of applications, and not arbitrarily restrictive.
The ASTM working group is taking important steps in a very critical
area. The working group will continue its activities. In addition,
a relevant
symposium is planned for May 2005. We will continue to keep you
posted.
We would like to thank ASTM Working Group F04.15.17 Chair, Dr.
Stephen Spiegelberg of the Cambridge Polymer Group, for his helpful
comments.
References:
a-d {. Kanegsberg, E. Kanegsberg, “Contamination Control In and Out of
The Cleanroom,” A2C2 Magazine, (April, May, June, 2003).
f B. Kanegsberg, E. Kanegsberg, TContamination Control In and
Out of The Cleanroom,” A2C2
Magazine, (October, 2003).
g W.G. Kenyon, Global Centre Consulting, personal communication.
h-k Œ. Kanegsberg, E. Kanegsberg, “Contamination Control In and
Out of The Cleanroom,” A2C2 Magazine, (December, 2002; January, February,
2003).
Note: B. Kanegsberg is a member of the ASTM F04.15.17 working
group concerned with “Standard Test Method for Assessing Extractable Residue in Implantable
Metallic Components.” Observations are based on participation at the
April 21, 2004 ASTM meetings, Salt Lake City, UT.
Barbara Kanegsberg
and Ed Kanegsberg are independent consultants in critical cleaning, precision
cleaning, surface preparation, and contamination control. They are the
editors of “Handbook for Critical Cleaning,” CRC Press. Contact
them at BFK Solutions LLC., 310-459-3614; info@bfksolutions.com; www.bfksolutions.com.
