Indium-111 pentetate (111In-DTPA)

Indium-111 pentetate, commonly known as In-111 DTPA, is a radiopharmaceutical complex consisting of the radionuclide Indium-111 chelated with diethylenetriaminepentaacetic acid (DTPA) (PubChem CID 165958). It is not a biological target such as a receptor or enzyme, but rather a diagnostic tracer used in nuclear medicine imaging (FDA Label). Its primary clinical application is radionuclide cisternography, where it is administered intrathecally to visualize the flow of cerebrospinal fluid (CSF) and identify abnormalities like hydrocephalus or CSF leaks (StatPearls). The molecule is highly stable and hydrophilic, ensuring it remains in the extracellular or CSF compartments without significant tissue uptake or metabolism. Following intravenous administration, it is cleared exclusively by glomerular filtration, making it a candidate for measuring renal function, though other tracers are more common for that purpose. Because it does not interact with specific biological receptors to elicit a therapeutic effect, it is classified as a diagnostic tool rather than a therapeutic target. Safety concerns are primarily related to the radiation dose and rare instances of aseptic meningitis following intrathecal injection.

Other names

Indium In-111 diethylenetriaminepentaacetic acidPentetate indium disodium In-111DTPA-indiumIndium-111 DTPAIndium In-111 pentetate

Indium-111 pentetate acts as a radioactive tracer that follows the physiological flow of cerebrospinal fluid (CSF) after intrathecal administration or is excreted via glomerular filtration after intravenous administration, allowing for scintigraphic visualization of fluid pathways.