iodine I-125 iothalamate

Action and Spectrum

Actions and Spectrum: 

• Diagnostic Imaging: iodine-125 iothalamate emits gamma radiation, which a gamma camera can detect. When administered to a patient, the kidneys excrete it, and the gamma camera can capture its distribution in the kidneys and surrounding tissues. This allows for evaluating kidney function and determining GFR, an essential measure of kidney health. 
• Radioactive Decay: iodine-125 is a low-energy gamma-emitting radionuclide with a half-life of approximately 59.4 days. This means that over time, half of the iodine-125 atoms will decay into other elements. The gamma radiation emitted during the decay process is used for imaging purposes. 
• Spectrum of iodine-125: The gamma rays emitted by iodine-125 have specific energies. The gamma photon energy spectrum of iodine-125 typically includes photons with energies of approximately 27 keV and 35 keV. These energies are relatively low, which makes iodine-125 suitable for imaging applications that require lower-energy gamma rays. 
• Biological Effects: The radiation emitted by iodine-125 is relatively low in energy, and the radiation exposure to patients during diagnostic imaging is considered safe and well-controlled. The amount of radioactivity administered is carefully calculated to minimize potential radiation risks while providing sufficient information for accurate diagnosis. 
• Radiation Safety: Medical professionals who handle iodine-125 iothalamate take appropriate safety precautions to minimize radiation exposure. Additionally, the patient’s excreta may contain radioactivity after the imaging procedure. Still, it is generally only a significant concern for others if specific instructions are given to handle waste safely. 

Drug Interaction

Adverse Reaction

None reported 

Black Box Warning

Black Box Warning: 

None 

Contraindication / Caution

Contraindication/Caution: 

Contraindications: 

• Known allergy 
• Pregnancy 

Cautions: 

• Renal impairment 
• Pregnancy 
• Pediatrics 
• Elderly 
• Acute renal injury 
• Drug interactions

Pregnancy / Lactation

Pregnancy consideration:  

No data is available. 

Breastfeeding warnings:  

No data is available. 

Pregnancy category: 

• Category A: well-controlled and Satisfactory studies do not show fetal risks in the first or later trimester.        
• Category B: there was no evidence of risk to the fetus in animal studies, and there were not enough studies on pregnant women. 
• Category C: there was evidence of risk of adverse effects in animal reproduction studies, and no adequate evidence in human studies must take care of potential risks in pregnant women.       
• Category D: adequate data with sufficient evidence of human fetal risk from various platforms, but despite the potential risk, and used only in emergency cases for potential benefits.        
• Category X: Drugs listed in this category outweigh the risks over benefits. Hence these categories of drugs need to be avoided by pregnant women.        
• Category N: No data for the drug under this category is available. 

Pharmacology

Pharmacology: 

• Radioactive Properties: iodine I-125 is a radioactive isotope of iodine, which emits gamma radiation with specific energies during its decay process. The gamma radiation is used for imaging purposes. 
• Half-Life: iodine I-125 has a relatively long half-life of approximately 59.4 days. This means that it takes nearly two months for half of the iodine I-125 atoms to decay into other elements. 
• Radiation Decay: When administered to a patient, iodine I-125 iothalamate undergoes radioactive decay. It emits gamma rays during this process, which a gamma camera can detect during imaging procedures. 
• Diagnostic Imaging: The primary use of iodine I-125 iothalamate is in renal imaging to assess kidney function and glomerular filtration rate (GFR). It is injected intravenously, and its distribution in the kidneys and surrounding tissues is captured using a gamma camera. 

Pharmacodynamics: 

• Radioactivity: iodine I-125 is a radioactive isotope of iodine. During its radioactive decay, it emits gamma radiation. This gamma radiation is used for diagnostic imaging purposes in nuclear medicine. 
• Diagnostic Imaging: iodine I-125 iothalamate is administered intravenously to patients undergoing renal imaging. After injection, it is rapidly cleared from the bloodstream by the kidneys and excreted in the urine. 
• Radiation Emission: The emitted gamma radiation from iodine I-125 is detected by a gamma camera, which captures the distribution of the radiopharmaceutical in the kidneys and surrounding tissues. This imaging allows the assessment of kidney function and the measurement of glomerular filtration rate (GFR). 
• Contrast Enhancement: Iothalamate, the non-radioactive component of the radiopharmaceutical, acts as a contrast agent. It enhances the visibility of the kidneys during imaging, providing detailed images that aid in diagnosing kidney function and potential abnormalities. 

Pharmacokinetics: 

Absorption 

iodine I-125 iothalamate is administered intravenously, which ensures rapid and complete absorption into the bloodstream. Once injected, it quickly enters the circulation and travels throughout the body. 

Distribution 

After absorption, iodine I-125 iothalamate is distributed throughout the body via blood circulation. The primary target tissue for imaging is the kidneys, which excrete radiopharmaceutical. 

Metabolism 

iodine I-125 iothalamate is not metabolized in the body. It remains in its original form during its imaging process. 

Elimination and Excretion 

The main route of excretion for iodine I-125 iothalamate is through the kidneys. The radiopharmaceutical is rapidly cleared from the bloodstream and excreted in the urine. This rapid renal clearance is essential for imaging the kidneys and measuring the glomerular filtration rate (GFR). 

Adminstartion

Administration: 

The administration of iodine I-125 iothalamate is performed in nuclear medicine for diagnostic imaging purposes, specifically to assess kidney function and measure the glomerular filtration rate (GFR). Using a gamma camera involves using radiopharmaceuticals to obtain detailed images of the kidneys and surrounding tissues. 

Patient Information Leaflet

Patient information leaflet 

Generic Name:  iodine I-125 iothalamate 

Why do we use iodine I-125 iothalamate? 

iodine I-125 iothalamate is used as a radiopharmaceutical in nuclear medicine for diagnostic imaging purposes. It primarily assesses kidney function and measures the glomerular filtration rate (GFR). GFR is a critical indicator of kidney health and function, and its measurement helps diagnose and monitor various kidney-related conditions.