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Dear All,
Could someone provide me some information about intrasubject
variability (CV)(Cmax or AUC) or an adequate number of volunteers to
a bioequivalence study of cetirizine and methyldopa?
I could find that n = 24 was adequate to methyldopa (Pubmed), but to
citirizine it hasn't any information. But I don't know if methyldopa
presents a highly variable pharmacokinetics disposition, because it
is a low solubility and permeability drug (BCS - class IV).
Any comments will be welcome.
Regards,
Daniel
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The following message was posted to: PharmPK
Hi Daniel,
There isn't a whole lot of information on cetirizine, but the literature
available suggests a relatively low variability. Your 24 subjects should
provide more than enough power. Here are a few references for
cetirizine:
(1) Spicak V et al. Clin Pharmacol Ther (1997);61(3):325-30.
(2) Simons FE et al. J Clin Pharmacol (1993);33(10):949-54.
(3) Desager JP et al. Clin Pharmacol Ther (1993);53(4):431-5.
(4) Watson WT et al. J Allergy Clin Immunol (1989);84(4 Pt 1);457-64.
(5) Lefebvre RA et al. Int J Clin Pharmacol Res (1988);8(6):463-70.
(6) Matzke GR et al. Ann Allergy (1987);59(6 Pt 2):25-30.
(7) FDA Review,
http://www.accessdata.fda.gov/scripts/cder/drugsatfda/index.cfm?
fuseaction=Search.Label_ApprovalHistory#apphist
If you look at half the total CV as a ballpark estimate for ISV, you're
looking at around 10-15% ISV for Cmax, less for AUCt.
Hope this helps,
David Dubins
PK Scientist
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The following message was posted to: PharmPK
Hi,
The problem with Cetirizine is the multiple peak phenomena. In our BE
study
there is not much variability about AUC, but Cmax and Tmax are
multiple and
differnt from 0.25 to 3 hours.
Dr. Sima Sadray
PharmPK Discussion List Archive Index page
Copyright 1995-2010 David W. A. Bourne (david@boomer.org)