Iothalamate Sodium I-125

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Cat Number

API0232094

CAS Number

17692-74-9

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Product Detail Description Customer Q&A

CAS Number

17692-74-9

Storage

Store at 2-8°C

Synonyms

Glofil-125; UNII-31J5U3Q9ZN; Natrii iotalamas (125 I); Iotalamato sodico (125 I); 31J5U3Q9ZN

Molecular Formula

C11H8I3N2NaO4

Molecular Weight

629.9

Smiles

CC(=O)NC1=C(C(=C(C(=C1[125I])C(=O)[O-])[125I])C(=O)NC)[125I].[Na+]

Appearance

Sterile aqueous solution

Boiling Point

520.2°C at 760 mmHg

General Description

Iothalamate sodium I‑125 is a radiolabeled ionic contrast agent incorporating the gamma‑emitting isotope iodine‑125 (half‑life 60 days) into the iothalamate molecule. The compound contains three iodine atoms, one of which is the radioactive isotope, while maintaining the chemical structure of a tri‑iodinated benzoic acid derivative. This low‑energy radionuclide emits 35 keV photons, making it suitable for in vitro and ex vivo tracer studies.

Mechanism of Action

Iothalamate is freely filtered at the glomerulus and is neither reabsorbed nor secreted by the renal tubules, so its clearance directly measures glomerular filtration rate (GFR). The I‑125 label allows quantitative detection via gamma counting. The high energy of iodine‑125 versus technetium‑99m is not ideal for imaging but provides excellent sensitivity for blood and urine samples, enabling precise pharmacokinetic analysis.

Application

Iothalamate sodium I‑125 is used exclusively as a research tool for measuring GFR in clinical pharmacology studies, particularly when repeated measurements are required or when patients have known allergy to other tracers. It is also employed in studies of renal transplant function and in the validation of alternative GFR markers.

Does Iothalamate Sodium I-125 require specialized storage due to its radioactive nature?

Yes, as a radiopharmaceutical with I-125 (half-life ~59 days), it must be stored in lead-shielded containers at controlled room temperature, with radiation monitoring and security protocols.

What is the radiochemical stability of Iothalamate Sodium I-125 during transport?

Shipments use shielded, temperature-controlled packaging with real-time tracking. Radiochemical purity is verified before dispatch, and degradation via radiolysis is minimized by limiting concentration and using stabilizers.

Is Iothalamate Sodium I-125 sensitive to light and heat?

Yes, both light and heat accelerate radiolysis. Store in light-resistant, refrigerated (2-8°C) conditions, and handle under subdued light to maintain radiochemical purity.

How is the free iodide impurity (I-125 as iodide) monitored during stability?

Free radioactive iodide is quantified using radio-TLC or radio-HPLC, ensuring it remains below regulatory limits (typically <5% of total radioactivity).