Trientine, also known as triethylenetatramine or abbreviation TETA, is a highly selective divalent Cu(II) chelator and orphan drug that reverses copper overload in tissues. It was approved as second-line pharmacotherapy for Wilson's disease. Wilson's disease (hepatolenticular degeneration) is an autosomal inherited metabolic defect resulting in an inability to maintain a near-zero balance of copper. Excess copper accumulates possibly because the liver lacks the mechanism to excrete free copper into the bile. Hepatocytes store excess copper but when their capacity is exceeded copper is released into the blood and is taken up into extrahepatic sites. This condition is treated with a low copper diet and the use of chelating agents that bind copper to facilitate its excretion from the body. Although penicillamine treatment is believed to be more extensive, TETA therapy has been shown to be an effective initial therapy. In addition, TETA is in a clinical trial phase II for the prevention of the Macular Edema after Cataract Surgery. TETA is also considered a potential chemotherapeutic agent as it could be a telomerase inhibitor. Chelating excess copper may affect copper-induced angiogenesis. Other mechanisms of action of TETA for alternative therapeutic implications include improved antioxidant defense against oxidative stress, pro-apoptosis, and reduced inflammation.