A Speech Of Understanding Ethylene Oxide Sterilization
Publish Time：2023-12-28
well welcome everybody thanks for coming out for this uh talk on understanding ethylene oxide sterilization just by a
quick show of hands how many people currently use ethylene oxide so we have a few and how many have never used it so
good good so we have a good mixture of the two so what we'll do is we'll talk a little bit about the introduction uh
some of the history of ethylene oxide some of the benefits of it um how it works then we'll get into how we design
a cycle uh you when you have a product you first have to design it with
sterilization in mind you want to find out can this product be sterilized with ethylene oxide what are the challenges to
that and then once you go into that find out what cycle you need then you go into the validation part of it and then
finally we'll talk about some uh recent changes to it so the standards so as an
introduction some of the advantages of ethylene oxide ethylene oxide just as a background it's used for about 56% of
medical devices that are sterilized in a large industrial scale so the other approximately half is done with
radiation so ethylene oxide radiation are the two main ways that you sterilize on a large scale ethylene oxide's real
Niche is low temperature so a lot of the plastic devices polymers things like that that can't withstand high
temperature like steam or dry heat or uh you know radiation material
compatibility is going to be an issue with radiation so ethylene oxide is very gentle on products so that's that's
another Advantage for that another advantage is it's it's considered an Overkill process which is in a way it's
almost an advantage and a disadvantage the advantage is that it uh it gives you a lot of safety Factor built into your
process so you're able to withstand larger fluctuations in your bioburden if you look at a process like radiation if
you have a spike in your bile burden your dose is set directly on exactly what your bile burden is and so if you
have a spike in your bile bird that can affect your sterilization validation that you've done with ethylene oxide there's so much Overkill built in into
it that it's going to allow you to withstand larger swings in that without having any issues with it can be a
little bit of a disadvantage because it is an Overkill process your cycle is going to be longer than it really needs
to just kill the product there's a there's a big safety Factor built in um penetration penetration is ethylene
oxide's main advantage you you look at things like uh vaporized hydrogen peroxide on paper you would think that
that would be a better sterilant because with vaporized hydrogen peroxide you're sterilizing in the range of like 1.2 mg
per liter with ethylene oxide around 650 Mig per liter so you would think that
that vaporized hydrogen peroxide would be a more powerful sterilant but the problem with that is it can't get into
the device to the areas on the device that it needs to get to be sterilized and so uh with ethylene oxide it's such
a small molecule it's very penetrating you'll actually penetrate through the walls of plastic so that's one of its
biggest advantages regulatory acceptance is another one it's been around for
approximately 60 years 60 70 years using it the way we use it today everybody's very familiar with it the FDA is
familiar with it regulatory bodies so if you're using an ethylene oxide process it's something people are used to seeing
and there's going to be a lot less questions than if you were trying to use a new novel approach the revalidation interval
that's an advantage as well you only have to revalidate uh by doing an actual physical run once every two years in
those off years you can do just a paper justification as long as nothing's changed to the process as long as you
haven't any failures non-conformances or problems with your process in that last
year you just assess the process and go through and then you can decide if you need to do a a physical run or not also
used for small or large volumes U small is just a couple of boxes all the way up to some Chambers hold more than 28
pallets a full tractor trailer so a wide range of flexibility for that little bit
of History again it's been around for a long long time and the 19 1920s they
first use it as an insecticide this is a picture of inside a grain elevator they used it a lot for grains and cereals and
things like that to kill insects and so they would put ethylen oxide in with dry ice and allow that to kind of fumigate
the grain elevators so in then then in the 1930s was the first time they used it to kill
microorganisms so kind of moving towards an approach like we use today where we're killing bacteria viruses molds
things like that and so that was in the late 1930s 19 40s they uh first started using
ethene oxide for food to preserve Foods they developed a cycle that was similar to what we use today and if anyone's
heard of stereogenic most the people that deal with ethylene oxide have heard of stereogenic before that they went
through some name changes it started out at Griffith Microscience um and then before that it was Griffith Laboratories
and this CL Griffith he was one of the ones that first started using this again they used it not for medical devices at
this point they were using it to sterilize foods and then Along Came World War II there's a big need for the
by the US government to get large quantities of food shipped over to Europe and to maintain that to feed the
troops so this is where they developed SE rations where they canned a lot of food and preserved it so they spent a
lot of time and effort using ethylene oxide to extend the shelf life of food a lot of the work by the government they
they did to optimize the parameters a lot of the parameters that you use with ethylene oxide it's very complex you
have temperature gas concentration relative humidity and exposure time
so all of those four parameters have to work in conjunction together to be effective and so there was a lot of
research on what happens if you change just the humidity or just the temperature and really with a lot of the
information we use today like a lot of things came out of the US government you working on it and so uh we still use
that today kind of some funny looking picture of an old sterilizer a pretty rudimentary they they used 55 gallon
drums when they first started out they put whatever materials they wanted to sterilize it they use these cans that
had a valve on there that they could open the valve allow the Ethan oxide to go into this Barrel basically and then
uh let it sit for a specified amount of time and then whatever was in there is sterile obviously today much more
complex um if you stop by 3m's Booth they have one of their sterilizers same one that's in that picture that has uh a
lot of a lot of functions as far as programmability you can program almost anything you want to how fast the gas
adds how fast the vacuums go so all computer controlled and so very very
obviously much more complex and the the process has really been optimized a lot since those early
days if you're using ethylene oxide sterilization you really have to understand the overkill method for all
types of sterilization except for radiation you use Overkill processes and
that's basically the concept of you're using a highly resistant biological indicator that you put in the hardest
part of your product and you got to show that you kill that in half the time so then your routine cycle is going to be
double that exposure time so that's be the amount of Overkill that we told you is built in so you find the time that it
takes to kill 1 million of the hardest to sterilize organisms in the hardest part of the product and then you're
going to double that processing time so really the cycle twice as long as it needs to be but that's really where you
get that flexibility and that process um a lot of you have probably heard the the
term sterility Assurance level of 10 Theus 6 that's basically one unit in a Million being non-sterile and so how we
do that is we use a biological indicator that has 10 6 or 1 million spores and by
killing that in half the time that's where you're going to show that process because then you're going to assume it it's considered to be first order
kinetics that you get the same kill rate in the second half of the cycle as you did in the first half of the cycle and
so by going through this if you show a six log reduction in one half of the cycle when you do the other half you're
going to get another six log reduction and so that's going to take you down to the 10 the minus 6 and that's what the
requirement for terminally sterilized devices
for okay we'll get into that in just a sec the question was how long does it take to sterilize in just a second we'll
show you how we go through and and actually determine how long the answer for that is really depends on the product and the load itself it can be it
varies from a lot of different times so when you're looking at ethylene oxide again we say we use these these
indicators that we put inside the product what we use is a Spore called it's an organism that forms a Spore a
Spore is kind of like a seed is to a plant it has a protective coat around it that's very resistant to chemical attack
it's resistant to heat and so it's very difficult to kill these organisms we're in that Spore state so this is called an
an organism called basilis atropus it's the indicator for ethylene oxide as well as dry heat sterilization every type of
sterilization has its own indicator organism steam sterilization uses an organism called geobacillus stero
thermophilus so with ethylene oxide we use this particular one it's a gr positive Spore forming organism nice
thing about it it has orange pigmentation so when you do the testing on it it's very easy to see just visually even if if you have what's
called a true positive or if it's a contaminant from from the testing process so it makes it very easy to work
with so why do we use bacteria spores a lot of times people will ask how can we use just this this one organism but
there might be viruses there might be molds there might be all these other types of microbes on my product and the
answer is that bacterial endospores are the most resistant entity to this type of sterilization again because they are
spor fer it's going to have that protective coat around that and so the the thought is you kill bacterial
endospores all these other organisms are so much less resistant that you're going to kill those as well that's why when
you do a sterility test you don't have to test for viruses for protozoa and
things like that that might possibly be on there viruses viruses are quite easily killed very easily killed with
that phen oxide so that's why we use bacterial spores that's kind of a key to ethylene oxide sterilization so we take
that organism and we put it on what they call a biological indicator typically it's just a paper strip that has the
spores of that bacillus organism they put a liquid suspension onto that allow it to dry and then they package that up
into a biological indicator and it it basically only has that one specific organism and then that's placed inside
the product inside the load and that's how you monitor sterilization after you sterilize the product you pull those out
you test them and you're looking for either growth or no growth and so that's what a biological indicator
is but the reason you can use just this biological indicator and not have to test your actual product is a lot of
times you'll develop what's called a processed challenge device this is something that if your product is very
expensive or it's something that's hard to get that biological indicator in the hardest part to sterilize you'll design
something that mimics the resistance of that but you don't have to use your actual product something that might be
very expensive some people have over product that's over $1,000 a unit so if
you had to to waste 20 of those samples just to put biological indicators in that's a lot of money where you could
maybe use something like a 5cent syringe or something very cheap and easy to work with so process challenge devices are
are very commonly used as well so now we get into the cycle and PCD development this is where we get
into how long your sterilization cycle may need to be when you look at your product you got to assess all the
different areas on that device that might be hard to sterilize uh things like stopcocks or closure systems
anything that has caps that close off the device it's going to restrict the gas getting into that part of the device
these are areas that we're going to challenge on the product if you have lumens long narrow Lumin again somewhere where the gas is going to have to get
down into that hardto sterilize part of the product these are all things you have to look at and determine if you can
sterilize it with ethylene oxide or not mated surfaces is another one that's one where two surfaces are pressed up
against each other again it's it's a barrier to get the gas down through that although it will penetrate through the walls of that syringe as well as through
the plunger itself so it is very penetrating but these are all things that you're going to look at sometimes
the packaging itself can be a barrier to sterilization so typically you're going to use something similar to tyvec or
paper most people use tyvec as a material that's a microbial barrier but
it's also breathable and permeable so that the gas can get into and get back out of it again so the the thing with
ethylene oxide sterilization there's a number of vacuum and pressure changes so you'll pull a deep vacuum you'll allow
air to come back in you'll do that multiple times because at the end of the cycle you have to get all of that
ethylene oxide back out of the product so you're going to pull multiple vacuums so the pressure changes the package has
to be able to withstand that if anyone's ever been uh camping or driven up in the mountains with a bag of potato chips the
bag expands and almost explodes because the internal pressure as you go higher
the atmospheric pressure is low lower so that bag is trying to the pressure inside can't equalize with the outside
so the bag swells up same thing with ethylene oxide when you pull a vacuum on the product the packaging needs to have
some way to equilibrate that pressure or you can end up bursting your seals and so that's why all types of packaging for
ethene oxide has to have some type of breathable area to allow that to occur foil pouches is an example of a foil
pouch would not be a good candidate for ethylene oxide sterilization unless you had some kind of tyvec header or
sometimes they have little patches of TC that allow that to the gas to get in and out back out again so that's the
packaging so once now we've taken our product we've looked at the different areas that we're going to sterilize and
then we have to inoculate those we have to test every one of those locations to make sure that the gas is going to be able to get in there and kill that
location FDA is very uh will commonly scrutinize where you inoculated so what
we'll tend to do is we'll inoculate multiple SES along the device and then as you go through and do the testing the
easy ones will drop drop out you're going to do a series of fractional cycles and so U try to find the goal is
you're going to try to find out what's the last site on the product that's going to survive and again when we
looked at all those different parts of those devices sometimes you can't get one of those big paper strips into the hardest
part of the device if you have a small narrow Lumen you might have to use something like this this is where we inoculate surgical sutures with the
liquid sport suspension so we're putting the spores on in an ethanol based solution that ethanol then flashes off
it evaporates off leaving just the spores onto that suture then you can place that suture down inside that
narrow Lumen or sometimes you use the liquid alone and put that on one of those mated surfaces where they're going
to be pressed up against each other so you'll put it on that surface allow the spores to dry on there and then reassemble the device so sometimes you
have to get very creative on how you're going to get the spores in the hardest part of the product that becomes one of the more difficult things and I I
mentioned we use process challenge devices a lot because you want to come up with something that you can use to to
to monitor the cycle so you don't have to use the actual product so we'll typically add a whole lot of different
ones we don't know which one's going to work at the beginning usually we have a fairly good guess so we'll try something
from low resistance medium and then high resistance to try to find one that's going to most closely simulate the
product because what the standard state is you have the process challenge device that you use has to be at least equal to
your product if not harder to sterilize than your product and so generally you know we'll try all these different ones
we'll put those process challenge devices that we're going to try we don't know again we don't know which one's going to work so we'll try several
different ones and we'll mix those evenly in with the product because we're doing a direct comparison of two different items we want to compare the
product to that process challenge device and again the product is going to be inoculated in multiple locations all
these different sites and then we're going to run fractional sterilization Cycles so we're going to do a run maybe
we do it 30 minutes then 60 minutes then 90 minutes after each run we pull those samples out test them and we're looking
to see if anything survives so you're just doing a regular sterility test of your biological
indicators it's a 7-Day test this is a little different from the product sterility test when you're you're testing your actual product that goes 14
days this is going to test for 7 days and you're just looking for for growth or no growth it's a plus or minus test
and so when you do that you tab you tabulate all the results in this case we did a study where we ranged from 15
minutes 30 60 90 120 and 15 minutes tested all these different areas in this
case it was a catheter type product so we tested multiple areas across the Lumen of of the middle the beginning the
middle and the closed off end of the catheter we tested any of those mated surfaces and then you see those last
three things called uh those are the different process
challenge devices that we use so again we tried different ones and we're not sure it's going to work and so you're
trying to find one that's equal to or greater than the product so if you look at the 60-minute column there all the
product sites are killed off so that's the end point for the product and so you're trying to assess which one of those three pcds is going to outlive be
equal to or outlive the product and as you can see all three of those at least
survived as much as the product if not more so any one of those could really be
used to monitor your process with does anybody see a problem with that first one that that has growth all the way
across we don't know when that dies off I mean we we go all the way out to 150 minutes and it's still alive problem is
is it may go all the way out to here maybe hours and hours to kill that so you always want to make sure you find an endo so you make sure you don't come up
with something that's too resistant and so any one of these can be used for your
product uh you just want to pick the one that's most appropriate and sometimes people will choose ones that that are
way more difficult than their actual product and what that'll do is that'll give you more flexibility down the road
if you design a new harder product than this particular product you can adopt that into your sterilization process
without having to go through and totally revalidate that and so it makes it easier the downside is is you may have a
longer cycle than you would otherwise need so it's a little bit of a balance of how much Overkill do you want in to
be able to add new products down the road versus how how short do I want to keep that process and how optimized do I
want it so does anybody have some ideas where you would inoculate this this is just one that we've come up with we put a
piece of tubing on a syringe does anybody see any locations on there that
that would be concerning to
you sorry yep where the plung the plunger is that's a mated surface there you also
have in the the barrel of the syringe itself the gas has got to get all the way down there that cap on the end
whether it's vented or non-vented could be a big deal if it's vented it's going to allow the gas to get into that more
more easily than if it's non-vented if that's a non-vented cap on that then the gas is going to actually have to
penetrate through the walls of the syringe or the tubing or the back side of that plunger to get in there so you
would inoculate most likely along the Lumen under the cap inside the syin and then possibly even on the threads of
where that where that lure lock screws onto that because that's going to be a mated surface as well and so as you can
see even if you have something that looks fairly simple and a lot of devices are way more complex than this that even
with this you would have multiple inoculation sites sometimes we'll get kits that have maybe 50 or 60 components
in there and you have to try to go through all of those those components to try to find what the most difficult to
sterilize so the next test that we do before we do the validation is bioburn enumeration this is a study where we're
going to find out how many microorganisms are on the device just through the manufacturing process after
it's gone through all the manufacturing steps up to but not including sterilization sometimes we get people
people that will send in samples to test for bile bur that have been sterilized obviously if you do that your Bob bur is
going to be very low because it's sterile so this is a test you do on non-sterile product but you want it to go be representative of going through
every step that you do because every time you handle the device you have organisms that just fall out from the
air and settle on top of on the surface of the device if you have any water steps where maybe there's a cleaning
process if that's allowed to sit wet a lot of microorganisms if there's water present they they will start to
reproduce and and can actually increase on the product so water is always a red flag um a lot of the organisms that live
in water can also cause endotoxin problems and so bioburden is is a step
that you do with ethylene oxide sterilization just like you do with all other types of sterilization um but it's
not quite as critical as it is with radiation with radiation you're taking the results from this test and setting
your cycle on that with ethylene oxide you're not setting your cycle length based on just that number that you're
going to get but it's going to be a judge of your manufacturing process it's going to show you how clean that product is or what the bioload on that is when
it's ready to go into sterilization and that's something that's normally done quarterly you're going to repeat that quarterly and you'll see that changes
over time as you add new people to your clean rooms um new raw materials maybe you change vendors all of that can
affect your bioburn you'll see it go up and down even with the seasons when it's warmer and wetter out more humidity in
there you'll see higher Bob bur levels than maybe in the winter when it's colder and drier and so all these can
affect that that's why you monitor it's a test you have to keep doing just to see what that bioload on your product
is another test we do which is similar to the comparative resistance in that test we actually inoculated the spores
into your device this one we just want to find out of all these things that are on the device through that handling and
through the through the environment are any of these things going to be overly resistant anything that has extreme
resistance to ethylene oxide because if you remember when we're monitoring the Cycles we're testing that biological indicator that just has that Spore strip
on there and so this is where we tie that together to determine that whatever's on that strip we compare it
to whatever happens to be on your device from your manufacturing process and we have to show that that process challenge
device is even more not only more resistant than when you put the spores in the hardest part of the device but
even more resistant than when you whatever just happens to be on your product sometimes organisms can mutate
and change and become extremely resistant so this is a screening test that you do periodically to make sure
you don't have any of these strange microorganisms on on your product that can cause problems so again how you do
it it's going to be very similar to what we did when we inoculated the product you're going to just test your actual
devices we're not going to even open it up at all we're just going to take the devices that are all packaged place them in the sterilizer next to that processed
challenge device that we came up with and we're going to do these same type of fractional sterilization Cycles expose
them to that then we're going to do a test on it in this case we do an actual sterility test on the product where
we're going to test the product on one hand and then that PCD on the other and we're just trying to show that whatever happens to be on the device whether you
have just a 100 organisms on there a th000 or maybe 10,000 that whatever is on there is not going to be more
resistant than that that biological indicator so it's a little bit different take on
that so now that we've done all this pre-testing this is all the stuff that we've gone up to the point we're ready to now go to a contract sterilizer and
then validate the process so this now we get into validation and there's a series of different cycles that you're going to
do as part of that you're going to an empty chamber profile this is where you're just testing the the chamber by
itself just to make sure that it's operating according to its specifications you're going to do a fractional cycle you want to show that
if samples have been exposed to ethylene oxide that when you do the sterility test then you're going to be able to
recover those and that sterility test would detect anything that might have survived so that's your fractional cycle
then you're going to do three half Cycles again you have to show that you kill those B in half the time so you're
going to have to do that three times to show show repeatability so you're doing it in triplicate and then you're going to do either one to three full Cycles a
minimum of one is required this is where you test the residuals because ethylene oxide is a toxic process you have to
remove that from the product before you can use it on the patient and so the residuals are are done that so again the
operational qualification this is the empty chamber profile this is just showing that without product in there
the sterilizer is acting like you think it should be that it's performing the way you expect and you're to compare
that temperature and humidity profile every year you look at that to make sure that the chamber performance isn't
degrading a lot of contract sterilizers will do a generic one for you and then you can just get that data from them
they'll provide that to you and that'll that just goes into your validation file each year you do a sublethal cycle again this
is is where you get some kill it's what they call the fractional zone or the quantal Zone this is what you like to
see hopefully you get some some growth and some kill because that way you can actually calculate exactly how much kill
you've you've gotten on that process and it gives you a point on that kill curve and that helps verify the amount of
lethality that you're getting it's just one of the requirements from the standard that if you're doing that half cycle method where you have to kill it
in half the time that you also have to do a fractional cycle where you show you can get some recovery so actually this
is the one time that that growth is a good thing you want to see growth there so then you do your half Cycles the
again this is where you're doing it in half the exposure time so if you had normally a six- hour exposure in your
routine cycle you're going to do a three-hour exposure this is where you prove that sterility Assurance level and it it has
to be done on your worst case situation really whatever you validate you're you're basically stuck with and so if
you want to do uh just as the same load size every single time then it's something that uh you're going to be
basically stuck with that same load size what some people want to do is they want to validate a range that gives them
anywhere from a minimum range of maybe just seven boxes say up to 10 pallets
and so you'll do half Cycles on both sides of those ranges from the minimum load as well as the maximum load find
out which one of those is worst case and then whichever one happens to be worst case and you'll do two additional ones
on that worst case situation so at the end of the day you have three half Cycles on your worst case situation so
if you do have multiple loading configurations or different products that you want to mix together you may do
more than three half Cycles because you have to figure out which one's your worst case first and then do three of whatever that happens to be your worst
case situation so then you do your full Cycles again the full cycle is just your
routine production cycle and what you're doing here is you're you're not only setting the ranges of the temperature
and humidity the physical parameters that you're going to go through from a normal production process so once you
get done with this you're going to go off of those temperature and humidity ranges but this is really where you find
your your uh residual testing because again it's a toxic product you need to
get that ethylene oxide off before it can be used but you you want to do your residual testing on samples that have
gone through a full uninterrupted cycle which which is your longest worst case cycle so that's where you do the
residual testing you don't do residual testing in half Cycles because that's only gone through half the exposure time
so you do it in the full cycle and then to make sure your product meets that so when you're looking at your
residual testing it really depends on the uh it depends on the contact that
the the device is going to have on the on the patient short-term contact anything less than 24 hours a lot of
times a catheter might only be used for say an hour or two hours falls into that category then you have prolonged contact
devices those are devices that are used for 24 hours up to 30 days and then you
have implants things that are permanent contact devices those are things that are meant to stay in basically for the
rest of the patient's life then those are greater than 30 days and those all have different limits for that
so as you can see the limits for the first 24 hours for the short-term contact are 4 and N 4 Mig of ethylene
oxide and 9 milligrams of ethylene chlorohydrin ethylene chlorohydrin is just a breakdown product of ethylene
oxide it's also a toxic compound so then what you do with these prolonged and permanent contact devices
you have to do what's called an exhaustive extraction that's where you you keep extracting the device until you get all of the ethylene oxide off if
it's a short-term contact device you don't have to do that you're only concerned with it's only used for 4 hours you're only concerned about the
amount that comes out to the patient during that short time so you don't have to get all of it out at that point but
for the next two categories you have to get all of it off to show what that total amount is and if it's a prolong
contact device you divide it by 30 days and that gives you those limits and if it's a lifetime contact you divide by
25,000 days so if you want to see how long you're going to live see how close you are to that 25,000 days cuz that's
what they consider a a life span it's about 70 years is what 25,000 days
are so those are the limits on that another thing that they added to
the standard was a thing called tolerable contact limit this was not in the previous version of the residual standard what this is is for only it
only applies to certain devices it's only going to apply for skin contacting devices something like maybe a surgical
gown something that's going to be on your skin that could possibly cause irritation because ethylene oxide can
cause irritation so they've set these other limits for skin contacting devices and implants that not only do you have
to meet the the limits that we showed you before but if it's one of those two categories you also have to meet these
either 10 micrograms per cim squar or 5 milligrams for ethylene chlorohydrin per
centimeter squared so it's based on the surface area of the device and that's just to prevent any localized irritation
that if you have two high levels of ethylene oxide or ethylene chlorohydrin that they could cause the patient have
irritation so it's an additional requirement that was added you also have a sample blank and
what the sample blank is it's something that basically is not exposed to EO at
all you're just trying to show that when you do the residual testing that there's nothing on the device that's either going to inhibit the presence of
ethylene oxide or enhance that so you don't want anything that's going to mass that presence of that so that would maybe be falsely identified as it so
it's really kind of a control just to show that when you do your residual testing that you know that really is that oxide the Peaks that you'll you'll
get on the gas chromatograph so that's the sample blank the standard has it's what again
one of the advantages of ethylene oxide is you don't have to validate every single year with radiation you have to validate quarterly every quarter you
have to do another dose audit to ensure because it's so dependent on your bio burden the nice thing about ethylene
oxide is you really truly only have to revalidate and do a a half cycle every other year as long as nothing's changed
you haven't changed your packaging your product the sterilization process or maybe even the equipment and so the
standard has this nice decision tree that helps you go through that process you assess what changes were made to the
process and whether those were minor changes or major changes if it's a minor change and what you may do is just do a
reduced qualification where you only do one half cycle so instead of doing all those cycles that we showed you before
three half Cycles maybe three full Cycles with your requalification if you've only made a minor change you may
only do one half cycle or best case scenario if you haven't seen anything any changes then what you'll do is uh
you'll just do a paper justification and you don't have to do an actual physical run you just take all the data you'll
look at your bioburden data you'll look at the history of any maybe non-conformances if you had any uh
failures during the year maybe a biological indicator grew you'll look at that and you'll assess if you really
need to do anything or not a lot of cases it's just a written justification that you're documenting everything that
nothing's changed so that uh that makes it a really nice advantage of that so
that's kind of it as for a basis for ethylene oxide is there any questions about what kind of testing is
required and generally we'll talk about this topic for 3 hours or 4 hours so this is kind of a crash course in 45
minutes so yeah right yeah the question was is there a requirement to inoculate
either lumens multiple times or other sides there's really a lot of guidance of exactly how in some cases it says use
the Judgment of a sterilization specialist um but you're exactly right A lot of times regulatory bodies the FDA
notified bodies will question why did you inoculate here but you didn't inoculate here and so it's a safer bet
to inoculate more places than fewer and then that way generally we'll inoculate sites that we know are going to drop off
in the very first short fractional cycles that way you have data for it you don't have to try to justify it because
anytime you justify anything there's always going to be somebody that doesn't agree with you and you're not going to be able to convince but there is no
requirement that you have to do multiple sites along alumen I mean we did a case where we did a closed in of alumen and
did the very far end where it was closed off where the gas had to penetrate all the way down there and we had a a FDA
auditor that said well how do you know the middle of the Lumen wasn't harder than that spot even though it was fairly
obvious because it was a closed system it only could get in through the one end they still required it to be done and
they had to redo that study and inoculate multiple locations so just to get around that we'll inoculate multiple
locations along that and then that way you don't have any questions you have data to back it up on even though you know that a lot of these will are going
to be a a challenge although sometimes we'll find sites that we think are going to be easy to kill and actually turn out
to be hard or the other way around you think they're going to be really hard and they turn out to be easy so
sometimes you you're not you're surprised by it so it doesn't hurt to do more more multiple locations on that
so good question thank you all right well that's it any other questions feel free
yes great great question the question was for bile bur resistance how often do you have to repeat that or is that a
one-time test we mentioned your bile bur's always changing so that's kind of the million-dollar question was well
when do I have to do it over again because you it's a test you really can't do one time and and put it in the file and never have to do it again because
your bio burden is always changing what the standard said is that you should repeat that at some periodic interval
that's not defined it doesn't say every year uh we recommend doing it annually if you're doing a recall every time you
do a re-qualification to repeat it then or if you have some unexplained or Adverse Events that happen with your
bober like suddenly you have a huge Spike that you've never seen before or your Bob just starts unex for some
unexplained reason going up and up then you want to make sure that you assess it at that point to make sure none of these
strange resistant organisms have been introduced into your process
so but again it's kind of up to your judgment of when you do that not not
clearly defined ISO 11135 right and that says there's a lot
of different things in there that will say you have to prove that the resistance of the bio burden is less than the Spore strips and things there's
several statements in there doesn't really tell you how to do it it just says you have to do that and then it's got to be repeated anytime there's a
change and things like that and so it's up to you as a manufacturer to kind of look at what Chang have been made and
then go from
there right
right yeah and what what the question is do I have to repeat bio burden quarterly that's uh it used to be in the old
version of 11135 it just said you had to establish what your bioburden was now it states that you have to go off of the
Bob burden standard which is 11737 part one so it actually specif ifies you do have to do that document that's more of
a recommendation I don't think even in that document it mandates you do it quarterly that document was written more
for radiation sterilization because it's so B burden heavy but uh that's generally what's done because it's
really more of a judge of your manufacturing process and it really is part of your sterilization validation so
doing it quarterly allows you to or at least multiple times during the year allows you to see any seasonal variation
or you know anytime you add new people to your clean room you fire somebody you hire somebody else they potentially may
be bringing in new bioburn that you didn't have before and so by doing it at some type of interval again there is
some leeway for you to establish what that may be the nice thing is once you characterize your bioburden and then
drop that back or once you characterize it and show it's consistent then you can reduce the number of samples and maybe
even the frequency because again with ethylene oxide it's not a bioburden based method
so all right well thank you so much for coming yes sir yeah the the point here
was that your the location of your facility can also affect your bio burden is that that correct and so if you have
multiple manufacturing sites you may have totally different bioburden makeup as well as numbers on the product so
it's important to assess that if you have multiple sites or or different locations so so good
point all right we'll let you go to lunch so thank you
quick show of hands how many people currently use ethylene oxide so we have a few and how many have never used it so
good good so we have a good mixture of the two so what we'll do is we'll talk a little bit about the introduction uh
some of the history of ethylene oxide some of the benefits of it um how it works then we'll get into how we design
a cycle uh you when you have a product you first have to design it with
sterilization in mind you want to find out can this product be sterilized with ethylene oxide what are the challenges to
that and then once you go into that find out what cycle you need then you go into the validation part of it and then
finally we'll talk about some uh recent changes to it so the standards so as an
introduction some of the advantages of ethylene oxide ethylene oxide just as a background it's used for about 56% of
medical devices that are sterilized in a large industrial scale so the other approximately half is done with
radiation so ethylene oxide radiation are the two main ways that you sterilize on a large scale ethylene oxide's real
Niche is low temperature so a lot of the plastic devices polymers things like that that can't withstand high
temperature like steam or dry heat or uh you know radiation material
compatibility is going to be an issue with radiation so ethylene oxide is very gentle on products so that's that's
another Advantage for that another advantage is it's it's considered an Overkill process which is in a way it's
almost an advantage and a disadvantage the advantage is that it uh it gives you a lot of safety Factor built into your
process so you're able to withstand larger fluctuations in your bioburden if you look at a process like radiation if
you have a spike in your bile burden your dose is set directly on exactly what your bile burden is and so if you
have a spike in your bile bird that can affect your sterilization validation that you've done with ethylene oxide there's so much Overkill built in into
it that it's going to allow you to withstand larger swings in that without having any issues with it can be a
little bit of a disadvantage because it is an Overkill process your cycle is going to be longer than it really needs
to just kill the product there's a there's a big safety Factor built in um penetration penetration is ethylene
oxide's main advantage you you look at things like uh vaporized hydrogen peroxide on paper you would think that
that would be a better sterilant because with vaporized hydrogen peroxide you're sterilizing in the range of like 1.2 mg
per liter with ethylene oxide around 650 Mig per liter so you would think that
that vaporized hydrogen peroxide would be a more powerful sterilant but the problem with that is it can't get into
the device to the areas on the device that it needs to get to be sterilized and so uh with ethylene oxide it's such
a small molecule it's very penetrating you'll actually penetrate through the walls of plastic so that's one of its
biggest advantages regulatory acceptance is another one it's been around for
approximately 60 years 60 70 years using it the way we use it today everybody's very familiar with it the FDA is
familiar with it regulatory bodies so if you're using an ethylene oxide process it's something people are used to seeing
and there's going to be a lot less questions than if you were trying to use a new novel approach the revalidation interval
that's an advantage as well you only have to revalidate uh by doing an actual physical run once every two years in
those off years you can do just a paper justification as long as nothing's changed to the process as long as you
haven't any failures non-conformances or problems with your process in that last
year you just assess the process and go through and then you can decide if you need to do a a physical run or not also
used for small or large volumes U small is just a couple of boxes all the way up to some Chambers hold more than 28
pallets a full tractor trailer so a wide range of flexibility for that little bit
of History again it's been around for a long long time and the 19 1920s they
first use it as an insecticide this is a picture of inside a grain elevator they used it a lot for grains and cereals and
things like that to kill insects and so they would put ethylen oxide in with dry ice and allow that to kind of fumigate
the grain elevators so in then then in the 1930s was the first time they used it to kill
microorganisms so kind of moving towards an approach like we use today where we're killing bacteria viruses molds
things like that and so that was in the late 1930s 19 40s they uh first started using
ethene oxide for food to preserve Foods they developed a cycle that was similar to what we use today and if anyone's
heard of stereogenic most the people that deal with ethylene oxide have heard of stereogenic before that they went
through some name changes it started out at Griffith Microscience um and then before that it was Griffith Laboratories
and this CL Griffith he was one of the ones that first started using this again they used it not for medical devices at
this point they were using it to sterilize foods and then Along Came World War II there's a big need for the
by the US government to get large quantities of food shipped over to Europe and to maintain that to feed the
troops so this is where they developed SE rations where they canned a lot of food and preserved it so they spent a
lot of time and effort using ethylene oxide to extend the shelf life of food a lot of the work by the government they
they did to optimize the parameters a lot of the parameters that you use with ethylene oxide it's very complex you
have temperature gas concentration relative humidity and exposure time
so all of those four parameters have to work in conjunction together to be effective and so there was a lot of
research on what happens if you change just the humidity or just the temperature and really with a lot of the
information we use today like a lot of things came out of the US government you working on it and so uh we still use
that today kind of some funny looking picture of an old sterilizer a pretty rudimentary they they used 55 gallon
drums when they first started out they put whatever materials they wanted to sterilize it they use these cans that
had a valve on there that they could open the valve allow the Ethan oxide to go into this Barrel basically and then
uh let it sit for a specified amount of time and then whatever was in there is sterile obviously today much more
complex um if you stop by 3m's Booth they have one of their sterilizers same one that's in that picture that has uh a
lot of a lot of functions as far as programmability you can program almost anything you want to how fast the gas
adds how fast the vacuums go so all computer controlled and so very very
obviously much more complex and the the process has really been optimized a lot since those early
days if you're using ethylene oxide sterilization you really have to understand the overkill method for all
types of sterilization except for radiation you use Overkill processes and
that's basically the concept of you're using a highly resistant biological indicator that you put in the hardest
part of your product and you got to show that you kill that in half the time so then your routine cycle is going to be
double that exposure time so that's be the amount of Overkill that we told you is built in so you find the time that it
takes to kill 1 million of the hardest to sterilize organisms in the hardest part of the product and then you're
going to double that processing time so really the cycle twice as long as it needs to be but that's really where you
get that flexibility and that process um a lot of you have probably heard the the
term sterility Assurance level of 10 Theus 6 that's basically one unit in a Million being non-sterile and so how we
do that is we use a biological indicator that has 10 6 or 1 million spores and by
killing that in half the time that's where you're going to show that process because then you're going to assume it it's considered to be first order
kinetics that you get the same kill rate in the second half of the cycle as you did in the first half of the cycle and
so by going through this if you show a six log reduction in one half of the cycle when you do the other half you're
going to get another six log reduction and so that's going to take you down to the 10 the minus 6 and that's what the
requirement for terminally sterilized devices
for okay we'll get into that in just a sec the question was how long does it take to sterilize in just a second we'll
show you how we go through and and actually determine how long the answer for that is really depends on the product and the load itself it can be it
varies from a lot of different times so when you're looking at ethylene oxide again we say we use these these
indicators that we put inside the product what we use is a Spore called it's an organism that forms a Spore a
Spore is kind of like a seed is to a plant it has a protective coat around it that's very resistant to chemical attack
it's resistant to heat and so it's very difficult to kill these organisms we're in that Spore state so this is called an
an organism called basilis atropus it's the indicator for ethylene oxide as well as dry heat sterilization every type of
sterilization has its own indicator organism steam sterilization uses an organism called geobacillus stero
thermophilus so with ethylene oxide we use this particular one it's a gr positive Spore forming organism nice
thing about it it has orange pigmentation so when you do the testing on it it's very easy to see just visually even if if you have what's
called a true positive or if it's a contaminant from from the testing process so it makes it very easy to work
with so why do we use bacteria spores a lot of times people will ask how can we use just this this one organism but
there might be viruses there might be molds there might be all these other types of microbes on my product and the
answer is that bacterial endospores are the most resistant entity to this type of sterilization again because they are
spor fer it's going to have that protective coat around that and so the the thought is you kill bacterial
endospores all these other organisms are so much less resistant that you're going to kill those as well that's why when
you do a sterility test you don't have to test for viruses for protozoa and
things like that that might possibly be on there viruses viruses are quite easily killed very easily killed with
that phen oxide so that's why we use bacterial spores that's kind of a key to ethylene oxide sterilization so we take
that organism and we put it on what they call a biological indicator typically it's just a paper strip that has the
spores of that bacillus organism they put a liquid suspension onto that allow it to dry and then they package that up
into a biological indicator and it it basically only has that one specific organism and then that's placed inside
the product inside the load and that's how you monitor sterilization after you sterilize the product you pull those out
you test them and you're looking for either growth or no growth and so that's what a biological indicator
is but the reason you can use just this biological indicator and not have to test your actual product is a lot of
times you'll develop what's called a processed challenge device this is something that if your product is very
expensive or it's something that's hard to get that biological indicator in the hardest part to sterilize you'll design
something that mimics the resistance of that but you don't have to use your actual product something that might be
very expensive some people have over product that's over $1,000 a unit so if
you had to to waste 20 of those samples just to put biological indicators in that's a lot of money where you could
maybe use something like a 5cent syringe or something very cheap and easy to work with so process challenge devices are
are very commonly used as well so now we get into the cycle and PCD development this is where we get
into how long your sterilization cycle may need to be when you look at your product you got to assess all the
different areas on that device that might be hard to sterilize uh things like stopcocks or closure systems
anything that has caps that close off the device it's going to restrict the gas getting into that part of the device
these are areas that we're going to challenge on the product if you have lumens long narrow Lumin again somewhere where the gas is going to have to get
down into that hardto sterilize part of the product these are all things you have to look at and determine if you can
sterilize it with ethylene oxide or not mated surfaces is another one that's one where two surfaces are pressed up
against each other again it's it's a barrier to get the gas down through that although it will penetrate through the walls of that syringe as well as through
the plunger itself so it is very penetrating but these are all things that you're going to look at sometimes
the packaging itself can be a barrier to sterilization so typically you're going to use something similar to tyvec or
paper most people use tyvec as a material that's a microbial barrier but
it's also breathable and permeable so that the gas can get into and get back out of it again so the the thing with
ethylene oxide sterilization there's a number of vacuum and pressure changes so you'll pull a deep vacuum you'll allow
air to come back in you'll do that multiple times because at the end of the cycle you have to get all of that
ethylene oxide back out of the product so you're going to pull multiple vacuums so the pressure changes the package has
to be able to withstand that if anyone's ever been uh camping or driven up in the mountains with a bag of potato chips the
bag expands and almost explodes because the internal pressure as you go higher
the atmospheric pressure is low lower so that bag is trying to the pressure inside can't equalize with the outside
so the bag swells up same thing with ethylene oxide when you pull a vacuum on the product the packaging needs to have
some way to equilibrate that pressure or you can end up bursting your seals and so that's why all types of packaging for
ethene oxide has to have some type of breathable area to allow that to occur foil pouches is an example of a foil
pouch would not be a good candidate for ethylene oxide sterilization unless you had some kind of tyvec header or
sometimes they have little patches of TC that allow that to the gas to get in and out back out again so that's the
packaging so once now we've taken our product we've looked at the different areas that we're going to sterilize and
then we have to inoculate those we have to test every one of those locations to make sure that the gas is going to be able to get in there and kill that
location FDA is very uh will commonly scrutinize where you inoculated so what
we'll tend to do is we'll inoculate multiple SES along the device and then as you go through and do the testing the
easy ones will drop drop out you're going to do a series of fractional cycles and so U try to find the goal is
you're going to try to find out what's the last site on the product that's going to survive and again when we
looked at all those different parts of those devices sometimes you can't get one of those big paper strips into the hardest
part of the device if you have a small narrow Lumen you might have to use something like this this is where we inoculate surgical sutures with the
liquid sport suspension so we're putting the spores on in an ethanol based solution that ethanol then flashes off
it evaporates off leaving just the spores onto that suture then you can place that suture down inside that
narrow Lumen or sometimes you use the liquid alone and put that on one of those mated surfaces where they're going
to be pressed up against each other so you'll put it on that surface allow the spores to dry on there and then reassemble the device so sometimes you
have to get very creative on how you're going to get the spores in the hardest part of the product that becomes one of the more difficult things and I I
mentioned we use process challenge devices a lot because you want to come up with something that you can use to to
to monitor the cycle so you don't have to use the actual product so we'll typically add a whole lot of different
ones we don't know which one's going to work at the beginning usually we have a fairly good guess so we'll try something
from low resistance medium and then high resistance to try to find one that's going to most closely simulate the
product because what the standard state is you have the process challenge device that you use has to be at least equal to
your product if not harder to sterilize than your product and so generally you know we'll try all these different ones
we'll put those process challenge devices that we're going to try we don't know again we don't know which one's going to work so we'll try several
different ones and we'll mix those evenly in with the product because we're doing a direct comparison of two different items we want to compare the
product to that process challenge device and again the product is going to be inoculated in multiple locations all
these different sites and then we're going to run fractional sterilization Cycles so we're going to do a run maybe
we do it 30 minutes then 60 minutes then 90 minutes after each run we pull those samples out test them and we're looking
to see if anything survives so you're just doing a regular sterility test of your biological
indicators it's a 7-Day test this is a little different from the product sterility test when you're you're testing your actual product that goes 14
days this is going to test for 7 days and you're just looking for for growth or no growth it's a plus or minus test
and so when you do that you tab you tabulate all the results in this case we did a study where we ranged from 15
minutes 30 60 90 120 and 15 minutes tested all these different areas in this
case it was a catheter type product so we tested multiple areas across the Lumen of of the middle the beginning the
middle and the closed off end of the catheter we tested any of those mated surfaces and then you see those last
three things called uh those are the different process
challenge devices that we use so again we tried different ones and we're not sure it's going to work and so you're
trying to find one that's equal to or greater than the product so if you look at the 60-minute column there all the
product sites are killed off so that's the end point for the product and so you're trying to assess which one of those three pcds is going to outlive be
equal to or outlive the product and as you can see all three of those at least
survived as much as the product if not more so any one of those could really be
used to monitor your process with does anybody see a problem with that first one that that has growth all the way
across we don't know when that dies off I mean we we go all the way out to 150 minutes and it's still alive problem is
is it may go all the way out to here maybe hours and hours to kill that so you always want to make sure you find an endo so you make sure you don't come up
with something that's too resistant and so any one of these can be used for your
product uh you just want to pick the one that's most appropriate and sometimes people will choose ones that that are
way more difficult than their actual product and what that'll do is that'll give you more flexibility down the road
if you design a new harder product than this particular product you can adopt that into your sterilization process
without having to go through and totally revalidate that and so it makes it easier the downside is is you may have a
longer cycle than you would otherwise need so it's a little bit of a balance of how much Overkill do you want in to
be able to add new products down the road versus how how short do I want to keep that process and how optimized do I
want it so does anybody have some ideas where you would inoculate this this is just one that we've come up with we put a
piece of tubing on a syringe does anybody see any locations on there that
that would be concerning to
you sorry yep where the plung the plunger is that's a mated surface there you also
have in the the barrel of the syringe itself the gas has got to get all the way down there that cap on the end
whether it's vented or non-vented could be a big deal if it's vented it's going to allow the gas to get into that more
more easily than if it's non-vented if that's a non-vented cap on that then the gas is going to actually have to
penetrate through the walls of the syringe or the tubing or the back side of that plunger to get in there so you
would inoculate most likely along the Lumen under the cap inside the syin and then possibly even on the threads of
where that where that lure lock screws onto that because that's going to be a mated surface as well and so as you can
see even if you have something that looks fairly simple and a lot of devices are way more complex than this that even
with this you would have multiple inoculation sites sometimes we'll get kits that have maybe 50 or 60 components
in there and you have to try to go through all of those those components to try to find what the most difficult to
sterilize so the next test that we do before we do the validation is bioburn enumeration this is a study where we're
going to find out how many microorganisms are on the device just through the manufacturing process after
it's gone through all the manufacturing steps up to but not including sterilization sometimes we get people
people that will send in samples to test for bile bur that have been sterilized obviously if you do that your Bob bur is
going to be very low because it's sterile so this is a test you do on non-sterile product but you want it to go be representative of going through
every step that you do because every time you handle the device you have organisms that just fall out from the
air and settle on top of on the surface of the device if you have any water steps where maybe there's a cleaning
process if that's allowed to sit wet a lot of microorganisms if there's water present they they will start to
reproduce and and can actually increase on the product so water is always a red flag um a lot of the organisms that live
in water can also cause endotoxin problems and so bioburden is is a step
that you do with ethylene oxide sterilization just like you do with all other types of sterilization um but it's
not quite as critical as it is with radiation with radiation you're taking the results from this test and setting
your cycle on that with ethylene oxide you're not setting your cycle length based on just that number that you're
going to get but it's going to be a judge of your manufacturing process it's going to show you how clean that product is or what the bioload on that is when
it's ready to go into sterilization and that's something that's normally done quarterly you're going to repeat that quarterly and you'll see that changes
over time as you add new people to your clean rooms um new raw materials maybe you change vendors all of that can
affect your bioburn you'll see it go up and down even with the seasons when it's warmer and wetter out more humidity in
there you'll see higher Bob bur levels than maybe in the winter when it's colder and drier and so all these can
affect that that's why you monitor it's a test you have to keep doing just to see what that bioload on your product
is another test we do which is similar to the comparative resistance in that test we actually inoculated the spores
into your device this one we just want to find out of all these things that are on the device through that handling and
through the through the environment are any of these things going to be overly resistant anything that has extreme
resistance to ethylene oxide because if you remember when we're monitoring the Cycles we're testing that biological indicator that just has that Spore strip
on there and so this is where we tie that together to determine that whatever's on that strip we compare it
to whatever happens to be on your device from your manufacturing process and we have to show that that process challenge
device is even more not only more resistant than when you put the spores in the hardest part of the device but
even more resistant than when you whatever just happens to be on your product sometimes organisms can mutate
and change and become extremely resistant so this is a screening test that you do periodically to make sure
you don't have any of these strange microorganisms on on your product that can cause problems so again how you do
it it's going to be very similar to what we did when we inoculated the product you're going to just test your actual
devices we're not going to even open it up at all we're just going to take the devices that are all packaged place them in the sterilizer next to that processed
challenge device that we came up with and we're going to do these same type of fractional sterilization Cycles expose
them to that then we're going to do a test on it in this case we do an actual sterility test on the product where
we're going to test the product on one hand and then that PCD on the other and we're just trying to show that whatever happens to be on the device whether you
have just a 100 organisms on there a th000 or maybe 10,000 that whatever is on there is not going to be more
resistant than that that biological indicator so it's a little bit different take on
that so now that we've done all this pre-testing this is all the stuff that we've gone up to the point we're ready to now go to a contract sterilizer and
then validate the process so this now we get into validation and there's a series of different cycles that you're going to
do as part of that you're going to an empty chamber profile this is where you're just testing the the chamber by
itself just to make sure that it's operating according to its specifications you're going to do a fractional cycle you want to show that
if samples have been exposed to ethylene oxide that when you do the sterility test then you're going to be able to
recover those and that sterility test would detect anything that might have survived so that's your fractional cycle
then you're going to do three half Cycles again you have to show that you kill those B in half the time so you're
going to have to do that three times to show show repeatability so you're doing it in triplicate and then you're going to do either one to three full Cycles a
minimum of one is required this is where you test the residuals because ethylene oxide is a toxic process you have to
remove that from the product before you can use it on the patient and so the residuals are are done that so again the
operational qualification this is the empty chamber profile this is just showing that without product in there
the sterilizer is acting like you think it should be that it's performing the way you expect and you're to compare
that temperature and humidity profile every year you look at that to make sure that the chamber performance isn't
degrading a lot of contract sterilizers will do a generic one for you and then you can just get that data from them
they'll provide that to you and that'll that just goes into your validation file each year you do a sublethal cycle again this
is is where you get some kill it's what they call the fractional zone or the quantal Zone this is what you like to
see hopefully you get some some growth and some kill because that way you can actually calculate exactly how much kill
you've you've gotten on that process and it gives you a point on that kill curve and that helps verify the amount of
lethality that you're getting it's just one of the requirements from the standard that if you're doing that half cycle method where you have to kill it
in half the time that you also have to do a fractional cycle where you show you can get some recovery so actually this
is the one time that that growth is a good thing you want to see growth there so then you do your half Cycles the
again this is where you're doing it in half the exposure time so if you had normally a six- hour exposure in your
routine cycle you're going to do a three-hour exposure this is where you prove that sterility Assurance level and it it has
to be done on your worst case situation really whatever you validate you're you're basically stuck with and so if
you want to do uh just as the same load size every single time then it's something that uh you're going to be
basically stuck with that same load size what some people want to do is they want to validate a range that gives them
anywhere from a minimum range of maybe just seven boxes say up to 10 pallets
and so you'll do half Cycles on both sides of those ranges from the minimum load as well as the maximum load find
out which one of those is worst case and then whichever one happens to be worst case and you'll do two additional ones
on that worst case situation so at the end of the day you have three half Cycles on your worst case situation so
if you do have multiple loading configurations or different products that you want to mix together you may do
more than three half Cycles because you have to figure out which one's your worst case first and then do three of whatever that happens to be your worst
case situation so then you do your full Cycles again the full cycle is just your
routine production cycle and what you're doing here is you're you're not only setting the ranges of the temperature
and humidity the physical parameters that you're going to go through from a normal production process so once you
get done with this you're going to go off of those temperature and humidity ranges but this is really where you find
your your uh residual testing because again it's a toxic product you need to
get that ethylene oxide off before it can be used but you you want to do your residual testing on samples that have
gone through a full uninterrupted cycle which which is your longest worst case cycle so that's where you do the
residual testing you don't do residual testing in half Cycles because that's only gone through half the exposure time
so you do it in the full cycle and then to make sure your product meets that so when you're looking at your
residual testing it really depends on the uh it depends on the contact that
the the device is going to have on the on the patient short-term contact anything less than 24 hours a lot of
times a catheter might only be used for say an hour or two hours falls into that category then you have prolonged contact
devices those are devices that are used for 24 hours up to 30 days and then you
have implants things that are permanent contact devices those are things that are meant to stay in basically for the
rest of the patient's life then those are greater than 30 days and those all have different limits for that
so as you can see the limits for the first 24 hours for the short-term contact are 4 and N 4 Mig of ethylene
oxide and 9 milligrams of ethylene chlorohydrin ethylene chlorohydrin is just a breakdown product of ethylene
oxide it's also a toxic compound so then what you do with these prolonged and permanent contact devices
you have to do what's called an exhaustive extraction that's where you you keep extracting the device until you get all of the ethylene oxide off if
it's a short-term contact device you don't have to do that you're only concerned with it's only used for 4 hours you're only concerned about the
amount that comes out to the patient during that short time so you don't have to get all of it out at that point but
for the next two categories you have to get all of it off to show what that total amount is and if it's a prolong
contact device you divide it by 30 days and that gives you those limits and if it's a lifetime contact you divide by
25,000 days so if you want to see how long you're going to live see how close you are to that 25,000 days cuz that's
what they consider a a life span it's about 70 years is what 25,000 days
are so those are the limits on that another thing that they added to
the standard was a thing called tolerable contact limit this was not in the previous version of the residual standard what this is is for only it
only applies to certain devices it's only going to apply for skin contacting devices something like maybe a surgical
gown something that's going to be on your skin that could possibly cause irritation because ethylene oxide can
cause irritation so they've set these other limits for skin contacting devices and implants that not only do you have
to meet the the limits that we showed you before but if it's one of those two categories you also have to meet these
either 10 micrograms per cim squar or 5 milligrams for ethylene chlorohydrin per
centimeter squared so it's based on the surface area of the device and that's just to prevent any localized irritation
that if you have two high levels of ethylene oxide or ethylene chlorohydrin that they could cause the patient have
irritation so it's an additional requirement that was added you also have a sample blank and
what the sample blank is it's something that basically is not exposed to EO at
all you're just trying to show that when you do the residual testing that there's nothing on the device that's either going to inhibit the presence of
ethylene oxide or enhance that so you don't want anything that's going to mass that presence of that so that would maybe be falsely identified as it so
it's really kind of a control just to show that when you do your residual testing that you know that really is that oxide the Peaks that you'll you'll
get on the gas chromatograph so that's the sample blank the standard has it's what again
one of the advantages of ethylene oxide is you don't have to validate every single year with radiation you have to validate quarterly every quarter you
have to do another dose audit to ensure because it's so dependent on your bio burden the nice thing about ethylene
oxide is you really truly only have to revalidate and do a a half cycle every other year as long as nothing's changed
you haven't changed your packaging your product the sterilization process or maybe even the equipment and so the
standard has this nice decision tree that helps you go through that process you assess what changes were made to the
process and whether those were minor changes or major changes if it's a minor change and what you may do is just do a
reduced qualification where you only do one half cycle so instead of doing all those cycles that we showed you before
three half Cycles maybe three full Cycles with your requalification if you've only made a minor change you may
only do one half cycle or best case scenario if you haven't seen anything any changes then what you'll do is uh
you'll just do a paper justification and you don't have to do an actual physical run you just take all the data you'll
look at your bioburden data you'll look at the history of any maybe non-conformances if you had any uh
failures during the year maybe a biological indicator grew you'll look at that and you'll assess if you really
need to do anything or not a lot of cases it's just a written justification that you're documenting everything that
nothing's changed so that uh that makes it a really nice advantage of that so
that's kind of it as for a basis for ethylene oxide is there any questions about what kind of testing is
required and generally we'll talk about this topic for 3 hours or 4 hours so this is kind of a crash course in 45
minutes so yeah right yeah the question was is there a requirement to inoculate
either lumens multiple times or other sides there's really a lot of guidance of exactly how in some cases it says use
the Judgment of a sterilization specialist um but you're exactly right A lot of times regulatory bodies the FDA
notified bodies will question why did you inoculate here but you didn't inoculate here and so it's a safer bet
to inoculate more places than fewer and then that way generally we'll inoculate sites that we know are going to drop off
in the very first short fractional cycles that way you have data for it you don't have to try to justify it because
anytime you justify anything there's always going to be somebody that doesn't agree with you and you're not going to be able to convince but there is no
requirement that you have to do multiple sites along alumen I mean we did a case where we did a closed in of alumen and
did the very far end where it was closed off where the gas had to penetrate all the way down there and we had a a FDA
auditor that said well how do you know the middle of the Lumen wasn't harder than that spot even though it was fairly
obvious because it was a closed system it only could get in through the one end they still required it to be done and
they had to redo that study and inoculate multiple locations so just to get around that we'll inoculate multiple
locations along that and then that way you don't have any questions you have data to back it up on even though you know that a lot of these will are going
to be a a challenge although sometimes we'll find sites that we think are going to be easy to kill and actually turn out
to be hard or the other way around you think they're going to be really hard and they turn out to be easy so
sometimes you you're not you're surprised by it so it doesn't hurt to do more more multiple locations on that
so good question thank you all right well that's it any other questions feel free
yes great great question the question was for bile bur resistance how often do you have to repeat that or is that a
one-time test we mentioned your bile bur's always changing so that's kind of the million-dollar question was well
when do I have to do it over again because you it's a test you really can't do one time and and put it in the file and never have to do it again because
your bio burden is always changing what the standard said is that you should repeat that at some periodic interval
that's not defined it doesn't say every year uh we recommend doing it annually if you're doing a recall every time you
do a re-qualification to repeat it then or if you have some unexplained or Adverse Events that happen with your
bober like suddenly you have a huge Spike that you've never seen before or your Bob just starts unex for some
unexplained reason going up and up then you want to make sure that you assess it at that point to make sure none of these
strange resistant organisms have been introduced into your process
so but again it's kind of up to your judgment of when you do that not not
clearly defined ISO 11135 right and that says there's a lot
of different things in there that will say you have to prove that the resistance of the bio burden is less than the Spore strips and things there's
several statements in there doesn't really tell you how to do it it just says you have to do that and then it's got to be repeated anytime there's a
change and things like that and so it's up to you as a manufacturer to kind of look at what Chang have been made and
then go from
there right
right yeah and what what the question is do I have to repeat bio burden quarterly that's uh it used to be in the old
version of 11135 it just said you had to establish what your bioburden was now it states that you have to go off of the
Bob burden standard which is 11737 part one so it actually specif ifies you do have to do that document that's more of
a recommendation I don't think even in that document it mandates you do it quarterly that document was written more
for radiation sterilization because it's so B burden heavy but uh that's generally what's done because it's
really more of a judge of your manufacturing process and it really is part of your sterilization validation so
doing it quarterly allows you to or at least multiple times during the year allows you to see any seasonal variation
or you know anytime you add new people to your clean room you fire somebody you hire somebody else they potentially may
be bringing in new bioburn that you didn't have before and so by doing it at some type of interval again there is
some leeway for you to establish what that may be the nice thing is once you characterize your bioburden and then
drop that back or once you characterize it and show it's consistent then you can reduce the number of samples and maybe
even the frequency because again with ethylene oxide it's not a bioburden based method
so all right well thank you so much for coming yes sir yeah the the point here
was that your the location of your facility can also affect your bio burden is that that correct and so if you have
multiple manufacturing sites you may have totally different bioburden makeup as well as numbers on the product so
it's important to assess that if you have multiple sites or or different locations so so good
point all right we'll let you go to lunch so thank you