indium In-111 pentetreotide

Action and Spectrum

Actions and Spectrum: 

Actions: 

indium In-111 pentetreotide is used primarily for imaging somatostatin receptor-positive tumors. Somatostatin receptors are overexpressed in certain neuroendocrine tumors and other malignancies. The peptide analog binds to these receptors, allowing for the visualization of the tumor and its metastases, if present. 

Spectrum: 

indium In-111 is a gamma emitter, which emits gamma rays during radioactive decay. The gamma rays have specific energies characteristic of indium-111, allowing for their detection by gamma cameras during SPECT imaging. The central gamma emission peak of indium-111 is at approximately 171 kilo-electron volts (keV). 

The gamma rays emitted by indium In-111 pentetreotide create images showing the radiopharmaceutical’s distribution and uptake in the patient’s body. These images provide valuable information about somatostatin receptor-positive tumors’ location, size, and metabolic activity. 

Drug Interaction

Adverse Reaction

Black Box Warning

Black Box Warning: 

None 

Contraindication / Caution

Contraindication/Caution: 

Contraindications: 

• Hypersensitivity 
• Pregnancy 
• Lactation 

Cautions: 

• Radiation 
• Renal impairment 
• Drug interactions 
• Pediatric use 
• Delayed imaging 

Pregnancy / Lactation

Pregnancy consideration:  

No adequate studies have been performed on the usage in pregnant women. 

But radiopharmaceuticals are harmful to the growing fetus. 

Breastfeeding warnings:  

Traces of the drug are found in breast milk. 

Pregnancy category: 

Category A: well-controlled and satisfactory studies show no risk to the fetus 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 is available for the drug under this category. 

Pharmacology

Pharmacology:  

indium-111: indium-111 is a radioactive isotope of the element indium. It emits gamma rays during radioactive decay, making it suitable for nuclear imaging. The physical half-life of indium-111 is approximately 2.8 days, which allows for delayed imaging, providing flexibility in the timing of scans. 

pentetreotide: pentetreotide is a synthetic peptide analog of somatostatin, a hormone that regulates various physiological processes in the body. pentetreotide has a high affinity for somatostatin receptor subtypes, particularly subtype 2 (SSTR2). This property enables it to bind to somatostatin receptor-positive cells, such as specific neuroendocrine tumor cells.  

Pharmacodynamics: 

indium In-111 pentetreotide is a synthetic peptide analog of somatostatin. It has a high affinity for somatostatin receptor subtypes, particularly subtype 2 (SSTR2), which are overexpressed in certain neuroendocrine tumors and other malignancies. When administered intravenously, indium In-111 pentetreotide circulates through the bloodstream and binds to these somatostatin receptors on the cell surface of somatostatin receptor-positive tumors. 

The gamma camera detects the gamma rays emitted by the radiotracer during SPECT imaging. The data obtained from the gamma camera is processed to create images that show the distribution and uptake of indium In-111 pentetreotide in the patient’s body. These images provide valuable information about somatostatin receptor-positive tumors’ location, size, and metabolic activity. 

Pharmacokinetics: 

Absorption 

indium In-111 pentetreotide is administered intravenously. Upon injection, it quickly enters the bloodstream and is distributed throughout the circulatory system. 

Distribution 

The radiopharmaceutical circulates in the bloodstream and distributes to various tissues and organs. The distribution depends on the blood flow to different body regions and the expression of somatostatin receptors, especially subtype 2 (SSTR2), in the targeted tissues. 

Metabolism 

indium In-111 pentetreotide undergoes minimal metabolism within the body. Its chemical structure is stable, allowing it to retain its binding properties to somatostatin receptors during imaging. 

Elimination and Excretion 

The elimination of indium In-111 pentetreotide primarily occurs through the kidneys. After somatostatin receptor-positive tissues have taken up the radiopharmaceutical, it is cleared from the bloodstream and excreted in the urine—the renal clearance pathway results in most radioactivity being eliminated from the body within a few days. 

Adminstartion

Administration: 

As with any nuclear medicine procedure, the administration of indium In-111 pentetreotide should be done by qualified healthcare professionals trained in nuclear medicine procedures.

The procedure should be performed by the facility’s radiation safety protocols and guidelines to ensure patient safety and accurate diagnostic information.

The decision to use indium In-111 pentetreotide should be based on the specific clinical indication and the patient’s medical history, considering the potential benefits of the imaging study for each case. 

Patient Information Leaflet

Patient information leaflet 

Generic Name: indium In-111 pentetreotide 

Why do we use indium In-111 pentetreotide? 

indium In-111 pentetreotide (also known as indium-111 DTPA-octreotide or In-111 octreotide) is used in nuclear medicine for diagnostic imaging of somatostatin receptor-positive tumors and certain neuroendocrine conditions