(-)-2β-Carbomethoxy-3β-(4-iodophenyl)tropane

(-)-2β-Carbomethoxy-3β-(4-iodophenyl)tropane (β-CIT or RTI-55) is a stimulant drug used in scientific research and with some medical uses, which was developed in the early 1990s. β-CIT is a phenyltropane based dopamine reuptake inhibitor and is derived from methylecgonidine. β-CIT is one of the most potent phenyltropane stimulants that is commercially available, which limits its use in humans, as it might have significant abuse potential if used outside of a strictly controlled medical setting. When radiolabeled with iodine-123, it is known as iometopane.

Uses
β-CIT is mainly used in scientific research into the dopamine reuptake transporter. Various radiolabelled forms of β-CIT (with different radioactive isotopes of iodine used depending on the application) are used in both humans and animals to map the distribution of dopamine transporters and serotonin transporters in the brain. The main practical application for this drug in medicine is to assess the rate of dopamine neuron degradation in the brains of sufferers of Parkinson's disease and some other conditions such as progressive supranuclear palsy.

Legal Status
β-CIT is legal in all countries throughout the world as of 2007. Some jurisdictions such as the USA, Canada, Australia and New Zealand might however consider β-CIT to be a controlled substance analogue of cocaine on the grounds of its related chemical structure.