iobenguane I-131

Action and Spectrum

Actions and spectrum: 

Iobenguane I 131 is taken up by the tumor cells and releases radiation, which damages the DNA of the tumor cells and causes their death. It is usually administered as an injection and is taken up by the tumor cells within hours, with the radiation being delivered over several days. The spectrum of iobenguane I 131 is limited to neuroendocrine tumors that have receptors for norepinephrine and dopamine, and it is not effective in other types of cancer.

It is also not recommended for use in patients with severe bone marrow suppression or those who are breastfeeding or pregnant due to potential radiation exposure to the fetus or infant. The medication should only be used under the guidance of a healthcare professional with experience in nuclear medicine. 

Drug Interaction

Adverse Reaction

Frequency defined 

>10% (All Grades) 

UTI (11%) 

Pyrexia (14%) 

Oropharyngeal pain (14%) 

Pain in extremity (15%) 

URTI (16%) 

Decreased weight (16%) 

Dehydration (16%) 

Back pain (17%) 

Dyspnea (18%) 

Cough (18%) 

Constipation (19%) 

Hypertension (20%) 

Abdominal pain (23%) 

Hypotension (24%) 

Dysgeusia (24%) 

Diarrhea (25%) 

Decreased appetite (30%) 

Headache (32%) 

Dizziness (34%) 

Sialadenitis (39%) 

Increased ALT (43%) 

Dry mouth (48%) 

Increased AST (50%) 

Increased phosphatase (53%) 

Vomiting (58%) 

Fatigue (71%) 

Nausea (78%) 

Neutropenia (84%) 

Increased INR (85%) 

Thrombocytopenia (91%) 

Anemia (93%) 

Lymphopenia (96%)  

>10% (Grades 3-4) 

Injection site pain (10%) 

Alopecia (10%) 

Dyspepsia (10%) 

Hyperhidrosis (10%) 

Tachycardia (10%)  

1-10% (Grades 3-4) 

UTI (1%) 

Decreased weight (1%) 

Sialadenitis (1%)
Dysgeusia (1%) 

Dry mouth (2%) 

URTI (2%) 

Back pain (2%) 

Pyrexia (2%)
Increase AST/ALT (2%) 

Tachycardia (3%) 

Diarrhea (3%) 

Hypotension (4%) 

Dehydration (4%) 

Decreased appetite (5%) 

Increased phosphatase (5%) 

Headache (6%) 

Abdominal pain (6%) 

Dyspnea (7%) 

Constipation (7%) 

Vomiting (10%) 

1-10% (Other) 

Hypothyroidism (3%) 

Pulmonary embolism (3%) 

Stomatitis (3%) 

Decreased TSH (5%)
Chest pain (6%) 

Candida infection (6%) 

GERD (6%) 

Muscle spasms (6%) 

Abdominal distension (6%) 

Petechiae (7%) 

Dysphagia (7%) 

Nasal congestion (7%) 

Pain in jaw (7%) 

Renal failure (7%) 

Chills (8%) 

Arthralgia (8%) 

Dry skin (8%) 

presyncope and syncope (8%) 

Neck pain (8%) 

Rash (8%) 

Prolonged prothrombin time (9%) 

Proteinuria (9%) 

Epistaxis (9%) 

Palpitations (9%) 

Insomnia (9%) 

Orthostatic hypotension (9%) 

Black Box Warning

Black Box Warning: 

The Black Box Warning for iobenguane I 131 includes two important safety warnings: 

• Radiation Risk: Iobenguane I 131 is a radioactive medication, and its use carries a risk of radiation exposure. The radiation emitted from the medication can cause harm to the patient, as well as individuals near the patient. Patients and their caregivers should follow proper radiation safety precautions as directed by their healthcare provider. 
• Myelosuppression: Iobenguane I 131 can cause severe bone marrow suppression, which can lead to life-threatening infections or bleeding. 

Contraindication / Caution

Contraindication/Caution: 

Contraindication: 

• Hypersensitivity: Patients who have a known hypersensitivity or allergy to iobenguane or any of its components should not receive iobenguane I 131. 
• Pregnancy: Iobenguane I 131 can harm a developing fetus and should not be used under caution pregnant women unless necessary. Pregnancy should be ruled out before administering iobenguane I 131, and effective contraception should be used during treatment. 
• Breastfeeding: It is not known whether iobenguane I 131 is excreted in human milk, and it is not recommended for use in breastfeeding mothers. 
• Severe bone marrow suppression: iobenguane I 131 can cause severe bone marrow suppression, which can lead to life-threatening infections or bleeding. The medication should not be used in patients with severe bone marrow suppression. 
• Uncontrolled hypertension: iobenguane I 131 can cause an increase in blood pressure, and it should not be used in patients with uncontrolled hypertension. 
• Children: The safety and effectiveness of iobenguane I 131 in pediatric patients have not been established, and it is not recommended for use in children.

Caution: 

• Renal Impairment: Patients with impaired renal function may be at increased risk of radiation exposure from iobenguane I 131 due to reduced clearance of the medication. Dose adjustment may be necessary in these patients. 
• Hepatic Impairment: Patients with impaired liver function may be at increased risk of radiation exposure from iobenguane I 131 due to reduced clearance of the medication. Dose adjustment may be necessary in these patients. 
• Radiation Exposure: Patients receiving iobenguane I 131 can expose others to radiation, including family members and healthcare workers. Appropriate radiation safety precautions should be taken, and patients should be advised to minimize close contact with others during and after treatment. 
• Secondary Malignancies: The use of iobenguane I 131 may have an increased risk of secondary malignancies, including myelodysplastic syndrome and leukemia. The risk of secondary malignancies should be weighed against the potential benefits of treatment. 
• Neurologic Effects: iobenguane I 131 can cause neurologic effects, including headache, dizziness, and paresthesia. Patients should be advised to report any new or worsening neurologic symptoms to their healthcare provider. 
• Concomitant Medications: iobenguane I 131 may interact with certain medications, including medications that affect the cardiovascular system, and caution should be exercised when administering these medications concomitantly.

Comorbidities: 

• Renal impairment: iobenguane I 131 is excreted through the kidneys, and its use should be avoided in patients with severe renal impairment. Dose adjustments may be required in patients with moderate renal impairment. 
• Hepatic impairment: iobenguane I 131 is primarily metabolized by the liver, and its use should be avoided in patients with severe hepatic impairment. Dose adjustments may be required in patients with moderate hepatic impairment. 
• Cardiovascular disease: iobenguane I 131 can cause an increase in blood pressure and should be used with caution in patients with cardiovascular disease, including hypertension, congestive heart failure, and arrhythmias. 
• Pulmonary disease: iobenguane I 131 can cause pulmonary toxicity and should be used with caution in patients with a history of pulmonary disease, including chronic obstructive pulmonary disease (COPD) and asthma. 
• Diabetes: iobenguane I 131 can cause an increase in blood glucose levels and should be used with caution in patients with diabetes. Blood glucose levels should be monitored closely during treatment. 
• Neurological disorders: iobenguane I 131 can cause neurological toxicity and should be used with caution in patients with neurological disorders, including seizures and peripheral neuropathy. 

Pregnancy / Lactation

Pregnancy consideration: pregnancy category: not assigned 

Lactation: It is not known whether iobenguane I 131 is excreted in human milk.  

Pregnancy category: 

• Category A: Satisfactory and well-controlled studies show no risk to the fetus in the first or later trimester. 
• Category B: There is no evidence when combined with risk to the fetus found in animal reproduction studies and there are not enough studies on pregnant women. 
• Category C: Adverse effects on the fetus found with evidence in animal reproduction studies and no adequate evidence for an effect in humans, care must be taken for potential risks in pregnant women. 
• Category D: There is adequate data available with sufficient evidence when combined with human fetal risk from various platforms, but despite potential risks may be used only in emergency cases for potential benefits. 
• Category X: Drugs listed in this category outweigh risks over benefits These category drugs should be prohibited for pregnant women. 
• Category N: There is no data available for the drug under this category. 

Pharmacology

Pharmacology: 

iobenguane I 131 is a radiopharmaceutical that combines the radioactive isotope iodine-131 with the synthetic analog of norepinephrine, iobenguane. It works by binding to norepinephrine transporters on the surface of neuroendocrine tumor cells, allowing the radioactive iodine to be delivered directly to the tumor. 

The radioactive iodine emits beta particles, which penetrate the tumor cells and cause damage to DNA, resulting in tumor cell death. The amount of radiation emitted by iobenguane I 131 is targeted and limited to the area of the tumor, minimizing damage to surrounding healthy tissue.  

Pharmacodynamics: 

The pharmacodynamics of iobenguane I 131 are related to its mechanism of action as a radiopharmaceutical. The therapeutic effect of iobenguane I 131 is therefore related to its ability to selectively deliver radiation to the tumor cells, while sparing surrounding healthy tissue.

The extent of tumor cell death depends on the dose of radiation delivered, which is determined by the amount of iobenguane I 131 administered and the specific characteristics of the tumor. 

The pharmacodynamic effects of iobenguane I 131 are monitored by imaging studies, such as a whole-body scan or single-photon emission computed tomography (SPECT), which can visualize the uptake of iobenguane I 131 in the tumor cells.  

Pharmacokinetics: 

Absorption 

iobenguane I 131 is administered as an intravenous injection and is rapidly distributed to target tissues, including neuroendocrine tumors. The medication is not absorbed through the gastrointestinal tract. 

Distribution 

iobenguane I 131 is highly protein-bound and is primarily distributed to tissues that express norepinephrine transporters, such as neuroendocrine tumors. The distribution of iobenguane I 131 is limited to the target tissue, minimizing exposure to surrounding healthy tissue. 

Metabolism 

iobenguane I 131 is metabolized by the liver, primarily through the process of deiodination. The metabolites of iobenguane I 131 are less active and are eliminated from the body. 

Elimination and excretion 

The elimination half-life of iobenguane I 131 is approximately 8 days. The majority of the medication is eliminated through the kidneys, with some elimination through feces and exhaled air. The radioactive iodine can also be excreted in urine, saliva, and sweat, and patients and their caregivers should follow proper radiation safety precautions to minimize radiation exposure to others. 

Adminstartion

Administration: 

iobenguane I 131 is a radiopharmaceutical that is administered as an intravenous injection under the supervision of a healthcare professional experienced in nuclear medicine. The dose and administration of iobenguane I 131 depend on several factors, including the patient’s body weight, the size and location of the tumor, and the patient’s kidney function. 

Prior to administration, patients may receive medications to protect the thyroid gland from the radioactive iodine, as well as medications to manage any potential side effects of the treatment. 

After the injection, patients may need to stay in a specialized radiation-shielded room for a period to minimize radiation exposure to others. Patients may also need to follow radiation safety precautions for a period after treatment, such as limiting close contact with others and disposing of bodily fluids properly. 

Patient Information Leaflet

Patient information leaflet 

Generic Name: iobenguane I-131 

Pronounced: [ EYE-oh-BEN-gwane ]  

Why do we use iobenguane I-131? 

iobenguane I 131 is a radiopharmaceutical used in the treatment of neuroendocrine tumors, including pheochromocytoma and paraganglioma, that have spread or cannot be surgically removed. iobenguane I 131 targets these tumor cells by binding to norepinephrine transporters, which are highly expressed on the surface of these cells.

Once iobenguane I 131 is taken up by the tumor cells, the radioactive iodine emits beta particles that penetrate the tumor cells and cause damage to DNA, leading to tumor cell death.