AngusMcLean
★★  

USA,
2010-10-02 04:23
(5738 d 05:03 ago)

Posting: # 5978
Views: 4,931
 

 coefficient of variation of drugs [Power / Sample Size]

I believe the error term from the ANOVA of the PK parameter values in a cross-over study (coefficient of variation) is used for the sample size calculation. It is calculated from the intra-subject between formulation error component.

Can I be advised if there is a compilation of CVs for drugs.

Angus McLean
Helmut
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Vienna, Austria,
2010-10-02 05:00
(5738 d 04:26 ago)

@ AngusMcLean
Posting: # 5979
Views: 4,118
 

 Compilation of CVs

Dear Angus,

answering your questions – or were they statements already? Yes, and yes.

❝ Can I be advised if there is a compilation of CVs for drugs.


Would be fantastic to have one… The only compilations I know are rather outdated:
  • Steinijans VW, Sauter R, Hauschke D, Diletti E, Schall R, Luus HG, Elze E, Blume H, Hoffmann C, Franke G, Siegmund W. Reference tables for the intrasubject coefficient of variation in bioequivalence studies. Int J Clin Pharm Ther. 1995;33(8):427–30.
  • Blume H, Mutschler E. Bioäquivalenz: Qualitätsbewertung wirkstoffgleicher Fertigarzneimittel. Frankfurt am Main/Eschborn: GOVI-Verlag; 1989-1996.
The former shows clearly the dependence of CVintra from the formulation (i.e., rectal diclofenac “behaves” nicely, whereas enteric coated definitely doesn’t). The latter is a four volume loose-leaf booklet of about 1500+ pages (in German) – you might get it used somewhere. It contains entire datasets (!) of all studies – something to play around with your software.
If you are looking for a particular drug, you may calculate the CVintra - which is rarely given – from the published confidence interval. See one of my lectures (slides 9-14) for the method. One big caveat if you want to rely on published data: see slide 15 – CVs from 37 studies on doxicycline; which one would you choose?

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