Advantages of Pre-Wetted Wipers in Sterile Environments By: Howard Siegerman, PH.D. April 2006
Untitled Document
Making a case for pre-wetted wipers versus a “build-your-own” philosophy
Introduction
If you had to describe the overriding characteristic of sterile environments
in one word, that word might be “uncompromising.” This word conveys
the sense that sterility requirements in these environments are indeed inflexible.
[1, 2]
It follows then, that items introduced into a sterile environment must not “compromise” or
pollute the area. Such items must themselves be sterile and must not introduce
unacceptable levels of contaminants—e.g. particles, residues, etc. Such
requirements apply equally (and ironically) to contamination control products
such as wipers and cleaning solutions that are used within the sterile areas.
These products are not excused from the inflexible requirements for sterility
and purity. Some pharmaceutical and biotechnology manufacturing plants have
adopted sterile pre-wetted wipers as the best way to address critical cleaning
issues in sterile environments. They have found that these cleaning products
allow them to achieve the best results in a cost-effective manner.
What are sterile pre-wetted wipers?
As the name suggests, these are cleanroom wipers that have been pre-wetted
with the optimum amount of 0.2 µm filtered solvent (typically 70% IPA
solutions) to accomplish the cleaning task at hand. Further, these pre-wetted
wipers are sterilized by gamma irradiation to a probability of non-sterility
(Sterility Assurance Level) of 10-6. This insures that only one wiper out
of a million would not be sterile.
Generally, sterile pre-wetted wipers are packaged in sufficient quantities
to last just one shift, on the premise that any consumable opened during
the shift will not be used in a subsequent shift. Enough wipers are packaged
to fulfill the wiping or cleaning requirements of that shift, with few, if
any, left over. This generally translates into 20-50 pre-wetted wipers per
package. The package is made from materials that will withstand gamma irradiation
at the necessary dosage levels, and that can be opened conveniently to withdraw
the pre-wetted wipers and closed (or resealed) to prevent evaporation of the
wetting solution.
Advantages of Sterile Pre-Wetted Wipers Contamination Control
These wipers, as delivered, are ready for immediate use to wipe down critical
surfaces before, during, and after production shifts, inside and outside the
sterile suite. Sterile pre-wetted wipers provide a means of sanitizing key surfaces
and simultaneously removing particulate matter that can act as transport vehicles
for bacteria. They are particularly useful for wiping down any articles brought
into the sterile suite, to sanitize those articles and to physically remove endotoxins
from surfaces.
Sterile pre-wetted wipers have been used for wiping down gloves to maintain
glove sterility during sterile suite activity. This has the advantage of simultaneously
sanitizing the glove and as well, physically removing dead bacteria from the
glove surface, thereby reducing or eliminating a potential source of endotoxins.
Spraying gloves with 70% IPA solution will sanitize the glove, but will not remove
the dead bacteria. Sterile pre-wetted wipers have been found to reduce the
incidence of false particle
alarms caused by IPA spraying.
These wipers are also used to wipe down surfaces that have been contacted
with environmental sampling devices such as Rodac plates, to remove residual
agar.
If this is not done, the agar on the sampled surface acts as a culturing
medium for opportunistic bacteria.
Elimination of Squirt Bottles
When alcohol is dispensed onto a dry wiper from a squirt bottle, often excessive
amounts of alcohol are used, since the operator’s gloves prevent tactile
feedback to indicate the optimum amount of dampness.
Since sterile pre-wetted wipers incorporate the optimum amount of 70% IPA for
contamination control activities, there is less alcohol used in the facility
and there may be an opportunity to eliminate squirt bottles and the transfer
of bulk solvent. This can represent cost savings in solvent expenses and in
charges for volatile organic compound (VOC) emissions. Also, sterile pre-wetted
wipers eliminate fugitive emissions from squirt bottle dispense nozzles and
from alcohol transfer operations.
Convenience
It would be difficult, but not impossible, to prepare sterile pre-wetted wipers
within the sterile suite. Users could follow these steps:
Bring sterile
dry wipers, packaging materials, graduated cylinders and sterile-filtered
70% IPA into the sterile environment.
Transfer the required number of wipers into the solvent-resistant packaging.
Transfer the required volume of sterile-filtered 70% IPA from the delivery
container onto the wipers.
Then close the packaging to allow the IPA
to thoroughly dampen the wipers and prevent the IPA from evaporating.
Of
course, all of the process steps would need to be documented and validated
to satisfy
regulatory audits. Also, this seems like a lot of manual effort, if
only 20 to 50 sterile pre-wetted wipers are needed for the shift.
Likewise, it would be difficult, but not impossible, to prepare sterile
pre-wetted wipers outside of the sterile suite. One could follow
the steps outlined
above except that non-sterile wipers would be used. Once the package
of pre-wetted wipers had been formed, the product would then be gamma
irradiated
and transferred
into the sterile suite. Now bioburden measurements, sterility validation
and
package integrity testing would also be needed in addition to the
usual documentation requirements.
It would appear that if one is going to employ sterile pre-wetted
wipers, they are best purchased rather than made in-house. The
vendor of these
products takes full responsibility for the necessary bioburden
measurements, sterility validation program, package integrity testing, certificates
of compliance
and irradiation and the process
audit trail. Also, the vendor enjoys the economies of scale to provide a lower-cost
product than could be made by the customer.
Summary
Sterile pre-wetted wipers are useful for the cleaning and maintenance of critical
surfaces inside and outside sterile suites and for wiping gloves during sterile
manufacturing processes.
References
“Guidance for Industry: Sterile Drug Products Produced by Aseptic Processing,” FDA,
(September, 2004) www.fda.gov/cder/guidance/index.htm
NOTE: This article was published in German in Steril Technik, June 2005.
Howard Siegerman is Director of Technology for the Texwipe Company,concen-trating
on contamination control in the electronic and life science markets.He earned
B.Sc.,M.A.and Ph.D. degrees in analytical chemistry from the University of
Toronto.Dr.Siegerman holds two patents and has authored a number of technical
publica-tions.He can be reached at 201-684-1800 x220 or hsiegerman@texwipe.com
ITW Texwipe,300B Route 17 South,Mahwah, New Jersey 07430.ITW Texwipe provides
products for contamination control.
Howard Siegerman is Director of Technology for the Texwipe Company,concen-trating
on contamination control in the electronic and life science markets.He earned
B.Sc.,M.A.and Ph.D. degrees in analytical chemistry from the University of
Toronto.Dr.Siegerman holds two patents and has authored a number of technical
publica-tions.He can be reached at 201-684-1800 x220 or 
