The disclosed opioid-related compounds and pharmaceutical compositions thereof, are useful in a variety of applications relating to the modulation of receptors and receptor signaling within and outside the nervous system. For example, the compounds and compositions are useful in methods for the treatment of addictions and other CNS-related disorders. The disclosed compounds can be delivered or administered to a mammal including humans, alone in the form of a pharmaceutically acceptable salt or hydrolysable precursor thereof, or in the form of a pharmaceutical composition, wherein a therapeutically effective amount of a compound is mixed with suitable carriers or excipients.