Back to the Top
Dear all
I want some views on sample size determination for a parallel BA/BE
study
Is it the same as cross over ?
Rgds
Sulagna
Back to the Top
The following message was posted to: PharmPK
Dear Sulagna.
Generally sample size for BA/BE studies is calculated by two models 1.
Multiplicative model and 2. Additive model, for cross over studies to
calculate sample size multiplicative model will be used where the sample
size depends on intra CV, Point estimate and power and the
calculation of
sample size for parallel studies depends on inter subject CV, point
estimate and power. Parallel studies requires more subjects than in the
cross over study since the inter subject variability is more in parallel
studies.
You can consider the following references :
Chow SC and Liu JP (1992) Design and Analysis of Bioavailability and
Bioequivalence Studies, Chapter 5: Power and Sample Size Determination,
Marcel Dekker Inc., New York.
Diletti E, Hauschke D and Steinijans VW (1991) Sample Size Determination
for Bioequivalence Assessment by Means of Confidence Intervals, Int J
Clin
Pharmacol Ther Toxicol 29(1);1-8.
Philips KF (1990) Power of the Two One-Sided Tests Procedure in
Bioequivalence, J Pharmacokin Biopharm 18(2);137-144.
Hope this helps,
With Regards,
V.Radhakrishna
Clinical Pharmacology and Pharmacokinetics
Back to the Top
hello every one
do you know any particular software to calculate sample size
determination. Because i am new in the field of BE studies.
secondly, How many volunteer are choosen for BE pilot study. suppose
if we are going to select 12,24,96.... Pl. give details.
thanks in advance
devisha
Back to the Top
Dear Devisha,
The number of subjects for a BE pilot biostudy are chosen depending
on the
requirement of the study. If you are doing a first time invivo study
with
new formulation usually 12 subjects are sufficient, only to know the
variability and Pharmacokinetics 8-10 subjects are sufficient, and for
highly variable molecules and to test the formulation 20-24 subjects are
sufficient.
There are many number of software's available to calculate sample
size for
BE studies.
Hope this helps,
With Regards,
V.Radhakrishna
Clinical Pharmacology and Pharmacokinetics
Back to the Top
The following message was posted to: PharmPK
Dear devisha
I don't know much about the sample size determination As per my
knowledge there is no specific software for it but you can decide it on
the basis of literature available from PUBMED or CDER website it also
depend on design of study. For pilot BE study the minimum no of
volunteers should be 12 as per the USFDA guidelines.
Vishal P Borikar
Glenmark Research Centre
Clinical Research Dept.
Turbhe,Navi Mumbai-400 705
Ph:022 56100560/61 Ext No.212
Back to the Top
The following message was posted to: PharmPK
Dear Dr Radhakrishnan
How does a pilot study help in determining variability of a
drug ? For
calculating variability of a drug an adequate number is the first
requirement. Few aberrant (very small or very high) values can give a
wrong
estimate. Often an insufficient sample size leads to fallacious results.
Pilot study has more to do with pk parameters of a drug and its
characteristics ....
Sulagna
Back to the Top
Dear Sulagna,
The pilot bioequivalence studies are done to know the deviation of test
product from the reference product and the error variance (intra
subject
CV) associated with the bioavailability parameters (AUC, Cmax) of the
drug
substance, to know this a small number of subjects are sufficient.
Pilot
BE study data is used to know the deviation of test product from the
reference product and to extrapolate the number of subjects required
in a
pivotal BE study depending on the above parameters.
Insufficient sample size in pivotal BE study may lead to fallacious
results.
With Regards,
V.Radhakrishna
Clinical Pharmacology and Pharmacokinetics
PharmPK Discussion List Archive Index page
Copyright 1995-2010 David W. A. Bourne (david@boomer.org)