This is a tough topic, have a look at the following references and see, if they can help you:
* Structural modelling and dynamics of proteins for insights into drug interactions.
* Ligand entry pathways in the ligand binding domain of PPARγ receptor
* Pathway and mechanism of drug binding to G-protein-coupled receptors
* Molecular Dynamic Simulation and Inhibitor Prediction of Cysteine Synthase Structured Model as a Potential Drug Target for Trichomoniasis