Understanding
the way glassware is depyrogenated and how high concentrations of endotoxin can
be used to assess how well depyrogenation tunnels are functioning is key to
quality control.
In
a new article, Tim Sandle explains:
Here
is an extract:
“The
regulatory standard for validation of an endotoxin inactivation (depyrogenation)
process is that it should be capable of reducing an endotoxin challenge through
3 log10 reduction. To ensure this limit works, it is required to clean
materials before dry heat depyrogenation with WFI. Otherwise, at least in
theory, you could have an item contaminated with 10,000 endotoxin units (EU)
entering a validated endotoxin inactivation process and still emerging with 10
EU intact and ready to contaminate your product.
Dry
heat depyrogenation is a complex process and is still poorly understood with
contradictory research data. The phenomenon that complicates the picture is
that inactivation may approximate to Second Order chemical kinetics with a high
initial rate of inactivation, then tail off to nothing. In practice, this means
that at any particular depyrogenating temperature you will get some degree of
inactivation in some period of time or other, but beyond that point, you will
get no further inactivation by holding the material at that temperature.”
Posted by Dr. Tim Sandle,
Pharmaceutical Microbiology Resources (http://www.pharmamicroresources.com/)
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