English: An accurate knowledge of nuclear parton distribution functions (nPDFs) is an essential ingredient of high energy physics calculations when the processes involve nuclei in the initial state. It is well known now that the prompt photon production in both hadronic and nuclear collisions is a powerful tool for exploring the parton densities in the nucleon and nuclei, especially of the gluon. In this work, we are going to perform a comprehensive study of the isolated prompt photon production in p-Pb collisions at backward rapidities to find the best kinematic regions in which the experimental measurements have most sensitivity to the nuclear modifications of parton densities. Most emphasis will be placed on the antishadowing nuclear modification. To this aim, we calculate and compare various quantities at different values of center-of-mass energy covered by the CERN Large Hadron Collider and also different rapidity regions to realize which one is most useful.