Re: I-131 therapy capsules

[carol marcus <csmarcus@ucla.edu>]

At 02:17 PM 4/19/00 -0500, you wrote:
>To all you nuc. med hospital types who previously used oral solution
>I-131 but now use I-131 capsules for therapy doses - how have your
>thyroid bioassay requirements (for personnel administering) changed (if
>they have) and what are they currently?
>
>Thanks,
>
>D. Steva
>University of Virgina
>
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Dear Ms. Steva:

There is no intellectually valid reason to perform thyroid bioassays on any
technologist or physician who administers NaI-131 in either capsule or
liquid form.  All commercially available preparations are stabilized against
volatility except for the CIS product, and that is stabilized by Syncor
before dispensing.  So, unless you are making NaI-131 in your own reactor
and using it for therapy, and I don't know anyone left in the USA who is,
and you are not stabilizing it, it is senseless to perform a bioassay.
About 10-12 years ago several nuclear pharmacists in different university
laboratories independently measured the volatility of all liquid and capsule
preparations.  Volatility was miniscule, and interestingly, higher for the
capsules than the liquid.  Inquiries to California, Texas, Florida, and the
NRC revealed not a single example of a thyroid bioassay beyond regulatory
limits in workers who administered any of these commercially available
products.  

These data were presented to NRC multiple times by me when I was on their
ACMUI, to no avail for over a decade.
Nonsensical as these bioassays are, it gives inspectors a box to check.  If
the NRC were truthful about "risk informed" requirements, it would have
gotten rid of the bioassay requirements as soon as it was shown the data.

Some Agreement States are scientifically enlightened and actually use
scientifically valid data.  At Harbor-UCLA Medical Center in California, we
are not required to perform thyroid bioassays.

Ciao, Carol

Carol S. Marcus, Ph.D., M.D.
Harbor-UCLA Research and Education Institute
<csmarcus@ucla.edu>

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