for understanding effectiveness of some kind of drug (macro liter unit ) on specific cell culture population ,which way is better? is it true that first i estimate IC50 of drug and test (that concentration =ic50)in different time (time dependent) OR just test drug from zero till IC50 density in one time for example after 48 hours ?generally pilot study have to be based on dose dependent or time dependent?
My opinion is that you should do the test at one time point (24 or 48h) and test a range of concentrations from 0 to n (minimum 5 - according to my experience) use concentrations that differ among - 10 times (eg. 10, 100, 1000,... microM).
My preference would be for more closely-spaced compound concentrations, such as 2-fold or half-log serial dilutions, with up to 10 concentrations. This is sufficient for preparing an EC50 curve. The range of concentrations tested should be determined experimentally. It can not be assumed that an IC50 determined by a cell-free assay will correspond to the EC50 for cell growth, and it is common for the EC50 to be much higher than the IC50. The time point will depend on the mechanism of the inhibitor and the growth rate of the cells.
There is two things.
First if you already know the effective concentration at which your sample active or reported somewhere else by other, then you proceed with Adam B Shapiro.
But if are working with entirely new commodity of drug then you have to first search the effective range and you have to proceed according to Nikola.