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October 2005


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Johan Bender <[log in to unmask]>
Reply To:
The Pharmaceutical Microbiology Forum Email List <[log in to unmask]>
Thu, 27 Oct 2005 10:21:47 +0200
text/plain (61 lines)
Lectori salutem,

I am looking for guidance on the interpretation of USP 788.  My
understanding is that the test is a measure of extraneous particles. I
am testing a powder product that I reconstitute for counting on an
automated particle counting system.  My product has multiple potencies
that are achieved by varying the reconstitution volume. I routinely
reconstitute to the highest prescribed volume and pool enough units to
achieve test volume.
* Given that the automated system will collect data on the number of
containers and total volume of solution to calculate the average number
of particles per container, does it matter what volume of diluent I use
in each container?
REPLY: mostly the counters have an automated dilution so most easy is to
dissolve worst case (i.e., resulting in the highest concentration of

* Also does anyone tie dissolution of powder solution with the testing
described in <788>?
REPLY: it is evident that the counting should be done in reconstitution
fluid identical to the one described in the package insert. In most
cases the active(s) will dissolve rapidly - the 788 guidance gives some
room to use ultrasonification to get rid of air bubbles. My experience
is: always use a ultrasound step.

* Should undisolved product be considered particles for this test <788>?
REPLY: yes.

* Am I routinely swaying the test in my favor by using the highest
REPLY: it depends if your counter has an automated dilution.

Regards - Johan Bender
Bactimm - Farmalyse BV, The Netherlands

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