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123I-Iomazenil is a radiopharmaceutical used in nuclear medicine for the imaging of benzodiazepine receptors in the brain. It is a radioligand that binds to the GABA receptor, which is the main inhibitory receptor in the brain.

Chemistry[edit | edit source]


123I-Iomazenil is a derivative of the benzodiazepine flumazenil, with the addition of an iodine-123 atom. This allows it to be detected by gamma cameras used in nuclear medicine imaging. The iodine-123 atom decays by electron capture to an excited state of tellurium-123, which then decays to the ground state by emitting gamma radiation.

Pharmacology[edit | edit source]

123I-Iomazenil binds to the benzodiazepine receptor site on the GABA receptor, but does not activate the receptor. This makes it an antagonist of the receptor. The binding of 123I-Iomazenil to the receptor can be displaced by other benzodiazepines, allowing it to be used to measure the occupancy of the receptor by these drugs.

Clinical use[edit | edit source]

123I-Iomazenil is used in single photon emission computed tomography (SPECT) imaging of the brain to measure the distribution and density of benzodiazepine receptors. This can be used to investigate conditions such as epilepsy, anxiety disorders, and drug addiction. It can also be used to measure the effects of drugs on the benzodiazepine receptor.

See also[edit | edit source]


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Contributors: Prab R. Tumpati, MD