Indium(III)-diethylenetriaminepentaacetic acid complex (Indium-DTPA)

Indium-DTPA (Indium(III)-diethylenetriaminepentaacetic acid complex) is a synthetic coordination compound in which the radionuclide indium-111 (In-111) is chelated by diethylenetriaminepentaacetic acid (DTPA). This complex possesses a coordination number of eight, with indium bound by three nitrogen atoms and five carboxylate groups from DTPA, resulting in a highly stable octadentate configuration optimal for in vivo applications[1]. Indium-DTPA is supplied as a sterile solution for use as a diagnostic radiopharmaceutical in radionuclide cisternography, where its gamma emissions are captured by imaging equipment for the assessment of cerebrospinal fluid dynamics and pathology[2][3]. It is not itself a therapeutic target but functions as a diagnostic tracer. Notable concerns include radiation exposure, rare cases of aseptic meningitis, and pyrogenic reactions, with radioactivity eliminated primarily via renal excretion[2][3]. The term “hapten” is not usually applied to indium-DTPA but may refer to antibody-targeting applications where DTPA is conjugated as a radiolabel; in such contexts, the “hapten” is a small molecule tag used for targeted imaging, though the chelator-metal complex itself is not a biological receptor or enzyme[1].

Other names

Indium-DTPAIndium In-111 pentetateIndium (111In) pentetic acidPentetate indium disodium In-111

Diagnostic tracer (gamma-emitting radionuclide complex used for imaging; acts by emitting gamma photons detectable with a gamma camera for anatomical mapping)