Re: C-14 Bioassay

["Quang Le"<qmle@icnpharm.com>]

I agree with Dr. Van Pelt. Requiring bioassay 2 weeks after working with
C-14 compounds may be too late. We have seen cases where someone turned in
a positive sample one day and a subsequent sample collected the very next
day shows no activity.

Biological half-lives depend largely on the chemical form of the compound.
Being as popular as carbon, the half-lives span a wide range.

If you only use a few C-14 compounds and have enough data related to those
specific compounds that show that certain bioassay frequency is
appropriate, you may modify or come up with your own model used to
calculate intakes (we did!). In that case, a 2-week frequency may be
appropriate.