Stability of CYP
activity in Bactosomes after repeated freeze-thawing
were subjected to a given number of freeze-thaw cycles, consisting of a
gentle thawing on ice, followed by a rapid re-freezing on dry ice.
Residual CYP activity was then measured, using Cypex's standard test
results are presented in the following graph as the residual CYP
activity (expressed as a percentage of control activity) remaining
after the indicated number of freeze-thaw cycles.
are expressed as mean ± SD, n=3, except where indicated (*),
where n=2 (mean ± range).
Activities measured were as follows: CYP3A4, testosterone 6b-hydroxylase;
CYP1A2, 7-ethoxycoumarin O-deethylase; CYP2D6 dextromethorphan
O-demethylase; CYP2C19 diazepam N-demethylase; CYP2C9, diclofenac
1A2 and 3A4 appear to be relatively refractory to the effects of
multiple freeze-thawing. CYPs 2D6, 2C19 and 2C9 show a decrease in
activity, although the effect is small (10-20% decrease after 5
under licence from BTG International Ltd (AU730155, EP0914446,
US6566108 and other patents pending).
United States Patent Nos. 5,420,027 or 5,240,831, Canada Patent No.
2100245 and other patents pending.