A pharmaceutical composition containing isomyosmine or a pharmaceutically acceptable salt thereof is administered to an individual in need thereof for treating a substance addiction, inclusive of affecting smoking substitution, eliminating cravings for tobacco and nicotine, or transitioning individuals away from smoking or the use of other tobacco products. In some examples, the therapeutic agent(s) are administered in a capsule, tablet, or lozenge. In other examples, the therapeutic agent(s) are administered via a chewing gum, inhalation spray, e-cigarette, nasal spray, or transdermal patch.