The Organic Cation/Carnitine Transporter (OCTN) family is a group of transmembrane proteins responsible for the transport of organic cations and carnitine into and out of cells. The main family members include OCTN1 and OCTN2, which consist of multiple transmembrane domains and are primarily located in the cell membrane of tissues such as the intestine, kidneys, and heart. OCTN transporters are involved in regulating the absorption and excretion of drugs, carnitine, and other nutrients, by affecting the transmembrane transport of these substances, regulating cell energy metabolism and pharmacological responses. The expression of OCTN family members is tissue- and cell-specific, and mutations or dysregulation of their genes are associated with various diseases, including carnitine deficiency disorders, Crohn's disease, and adverse drug reactions.