- On 9 Sep 2005 at 20:35:45, "sulagna" (sdas.aaa.clinsearchlabs.com) sent the message

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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 - On 12 Sep 2005 at 16:30:41, radhakrishnav.aaa.drreddys.com sent the message

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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 - On 12 Sep 2005 at 22:51:45, deva krish (devishabana.aaa.gmail.com) sent the message

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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 - On 13 Sep 2005 at 10:48:18, radhakrishnav.at.drreddys.com sent the message

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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 - On 13 Sep 2005 at 12:51:32, "Vishal P. Borikar" (vishalb.-a-.glenmarkpharma.com) sent the message

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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 - On 14 Sep 2005 at 09:55:02, "sulagna" (sdas.at.clinsearchlabs.com) sent the message

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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 - On 16 Sep 2005 at 10:53:48, radhakrishnav.-at-.drreddys.com sent the message

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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

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