Bioequivalence and Bioavailability Forum

Hi Ken,

the idea of ISR is to obtain information about potential problems with reproducibility (metabolite inter­action, sample homogeneity) within the entire range of con­cen­tra­tions. Obviously the highest concentrations are expected around C_max and the lowest in the elimination phase. Some regulators expect samples to be selected before starting the analyses. This works only if

1. The expected t_max is known to the analyst – ask the sponsor beforehand!
   
2. Enough sample for duplicate analysis is available in all cases.

If it turns out that the volume of a particular sample is too low, state in the protocol that you will use e.g. the nearest adjacent sample in the profile with sufficient volume.