Therefore, the activity of chalcones is dependent on the cumulative concentration of irreversibly bound chalcones or possible metabolite to the target. The free drug concentration will always determine the initial binding kinetics of the chalcones to the target or the site of action, but the subsequent time course of receptor occupancy and the pharmacodynamics events that the chalcones triggers do not follow the time course of free drug concentration. This is because the efficacy of the chalcones will depend on the inactivation of the biological target and the time taken for the body to resynthesize the biological target and not on the free drug concentration in plasma. The results of the clearance and half-lives of the selected hybrids are presented in Table .