Bioequivalence and Bioavailability Forum

Dear Ambati!

❝ what is the intention of calculation of AUC_%Extrap_obs in BA/BE studies

If your assessment of bioequivalence is based on AUC_inf you have to have some means to check whether your extrapolation beyond the time points of measured concentrations is reasonably low. Generally a coverage of 80% (AUC_last/AUC_inf) is considered sufficient (EMEA, WHO, Australia, Malaysia, Brazil, South Africa,...). Other guidelines (e.g., FDA) mention only '3 to 5 half-lives' - which for any >1-compartment model can have a total different meaning.
For details see this thread.

❝ and shall we exclude any subject from statistical analysis based on this calculated result.

It's up to you. But think it over beforehand - based on clinical grounds, the PK characteristics of the drug and/or formulation, etc. - and lay it down in the statistical analysis plan.

❝ what is the usage of Partial areas option which available in WinNonlin software...

RTFM of WinNonlin.
It's a metric to characterize the rate of absorption suggested by the FDA ('early exposure'). See the repective guideline.

❝ ...shall we use this method in the calculation of AUC instead of AUC truncated method.

No! Truncated AUC is a metric for extent of absorption (FDA: 'total exposure') for long half life drugs.

Consider reading one of the textbooks on BA/BE before using software on a serendipitous scale.